Warm engine does not start motorcycle

Why won't my motorcycle start?

Imagine: Sunday, great weather, in the mood to go for a ride. In anticipation of a pleasant trip, you approach your Yamaha Drag Star 400 cruiser, insert the key into the ignition, turn it, but you can’t hear the usual sound. And it would be nice if there was silence, but the car makes strange, unpleasant creaks or even “shots”. This situation can happen with any bike (both Ducati and Honda), with any motorcycle owner. Weekend ruined? Not if you correctly identify the cause and eliminate it. Our article will help you do this.

Checking the starter. Does it work when you press the button?

A suddenly dead battery or a malfunction in the ignition system will not be a problem for you if you know how to jump start a bike. But if you can’t launch it from kickstarter, you can’t do it without contacting a motorcycle service center.

If everything is fine with the starter, the problem may be in the air-fuel mixture ignition system. In normal condition they should be light brown and dry. If they smell of fuel, are black and wet, and gasoline falls into the combustion chamber, the cause may be careless handling of the equipment or a malfunction of the bike. Dry and blow out the spark plugs, put them back in place and try to start the engine again. And always carry a set of spare candles with you, especially on long tourist trips in unfamiliar areas, so that trouble does not take you by surprise far from civilization.

Quick diagnostics

Since in the future the problem of popping noises in the muffler can lead to breakdown of the engine and other important components of the motorcycle, it needs to be solved as quickly as possible. You should consistently check the performance of systems such as: intake, ignition, exhaust. All damaged parts are replaced with new ones, connections are sealed. It is also better to temporarily replace tuning components with “stock” ones to check how the engine will perform with factory settings. If all else fails, the motorcycle should be inspected by a professional mechanic, who will find the cause and tell you how to eliminate it at minimal cost and without reducing the life of the power unit.

We welcome every motorbike enthusiast! The “Questions and Answers” section was created for informational purposes. Each of you should know why his iron horse has certain problems in operation.

Many of you will be interested to know why the motorcycle shoots. There is no need to wait until this trouble appears. Find out how to protect your steel horse.

Often the bike makes sounds that remind us of sneezing or gunshots. This is quite strange, but understandable. This problem affects not only the much-criticized motorcycles of the USSR. A similar oddity can occur when using vaunted foreign motorcycles.

The reasons for the firing of motorcycle equipment can be associated solely with the process of ignition of the fuel mixture in the cylinders of the iron horse. If the electronics system is not configured correctly or gasoline is not supplied to the internal combustion chamber in its pure form, you should not wonder why the motorcycle is firing. Both Soviet bikes and foreign steel horses do not tolerate low-quality gasoline. If the latter contains an excessive amount of water, the iron horse, as usual, makes dull hissing sounds that resemble “CHHI.”

If there is a problem in the ignition system (the advance is knocked down, for example, on the contacts), motorcycle equipment also does a poor job of burning fuel, as in the case of poor quality fuel).

Instead of asking yourself the above question, ask yourself how it is possible to maintain such a bad ignition system on a two/three wheeler or put bad fuel into it. Yes, gasoline that is of excellent quality can become clogged directly in the carburetor of your bike. Cleaning filters to avoid such a nuisance or buying new consumables of this type is a mandatory norm for modern operation of the iron horse!

A motorcycle sneezes for a reason. Its systems resemble the human body. If the latter is also not in order, it produces strange defensive actions.

Motorcycle won't start when hot

The opposite situation also happens: a cold bike starts without problems, but after a short stop you need to wait 5–10 minutes. In this case, the larger the engine volume, the more pronounced this difficulty becomes. It is rare on maxi-scooters and 250 cc cars, but much more common on powerful bikes (for example, the 1198 cc Ducati Diavel or 1170 cc BMW R1200RT). The solution is to adjust the valve clearance, which, when expanded, does not provide the necessary compression. Also, for a “hot” start, motorcycle manufacturers install a Hot Start lever; use it if it is installed on your model.

#21 22.06.2012 12:48:26

AM02RUS Three times Sibikhod Real name: Radik Motorcycle(s): temporarily Kick Scooter XT From: Mytishchi (sometimes Ufa) Registered: 05/29/2006 Posts: 8866

Re: Hard to start, stalls and stalls when hot

Sometimes I even spin the X until the cutoff, then click the second, click the third, and damn, I already have to slow down.
And on Sibivan I almost always rode at this rhythm on weekends. The word skating is used here in the sense in which everyone is accustomed to understanding it, i.e. These are weekend rides unlimited in time and directions, mostly on empty roads. Naturally, I went to work calmly, because Yaroslavka from Mytishchi to the Third Transport Ring is almost completely stopped. I'm a boring creature. I'm a bore, I'll bore and force anyone I want.

The motorcycle starts and immediately stalls

The engine may suddenly stall due to an ignition or power failure. Mechanical breakdowns of the chassis are much less common. The engine immediately stalls if it does not have enough fuel or, conversely, there is too much of it, and the reason for this may be a malfunction of the spark plugs, carburetor, fuel pump or hoses. Tuning and flushing the carburetor will be the most likely solution. If the spark plugs are cleaned and the carburetor is working properly, the breakdown will probably be found in the ignition coil or starter enrichment.

The motorcycle does not start and the muffler shoots

This also happens: the bike completely refuses to start and makes “shooting” sounds. This result is caused by improper care of the ignition system, the use of low-quality gasoline, breakdown of the electronics that regulate the supply of gasoline, and fuel accumulation in the muffler. And this is not just about the aesthetic impression of your car. If you drive for a long time with a dirty carburetor or on bad gasoline, the compression of the engine cylinders will be disrupted, which will lead to engine failure.

If you have a rev limiter, part of the fuel-air mixture enters the exhaust system, where it ignites from the hot metal. This effect is used by the creators of shows in which bikes have flames flying out of the exhaust pipe.

To prevent problems with starting the engine, check the level of oil, brake fluid, and antifreeze before driving. Leaky connections can allow moisture to get inside, which is the main cause of rust. Store the bike with a full tank of fuel, otherwise it will cause condensation. Before long-term storage, remove the battery and leave it charged in a cool place at above-zero temperatures. And remember, most often the reason for the engine’s reluctance to start is the inattention of its owner.

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The essence of the problem

Most often, loud pops in the muffler are heard when a lean mixture is supplied to the engine. The reason for its formation may be the use of low-quality gasoline, saturated with water and non-flammable impurities, or incorrect adjustment of the intake system. The air-fuel mixture burns only partially - its remains splash out into the hot muffler, where they explode with sharp, unpleasant sounds. A symptom of a lean mixture is popping sounds in bursts, which intensify as the speed increases.

In powerful motorcycles, the completely opposite problem is more common, associated with the supply of an excessively rich mixture. There is not enough oxygen for its combustion, which leads to the deposition of gasoline condensate on the walls of the muffler. When the “critical mass” is reached, the fuel outside the engine ignites, resulting in one loud bang. If the problem is not corrected, within 1-2 months the contents of the muffler will simply burn out and it will turn into a “direct flow”.

Incomplete combustion of the mixture may be caused by a malfunction of the ignition system. In the absence of a spark, the cylinder misses a power stroke and the full amount of gasoline enters the muffler. Loud sounds are most often heard in this case at high speeds. The problem is also fraught with complete burnout of the muffler from the inside. Misfires are often accompanied by beautiful visual effects - when the engine is overloaded, jets of flame fly out of the exhaust pipes.

Another option is a lean mixture in the intake system caused by air, dirt or water getting into it. Naturally, the fuel does not burn completely and drops of gasoline form on the walls of the muffler, burning with a sharp, characteristic sound. In any case, the motorcycle malfunction must be repaired as soon as possible so as not to encounter more serious repairs.

What to do if your motorcycle won't start?

A motorcycle engine is a complex system that, unfortunately, is susceptible to negative environmental influences. If your motorcycle does not start, the reasons may be different, but by following simple steps, you can fix minor problems without the help of specialists.

If your battery is fully charged, you have carried out diagnostics and visually assessed the condition of all parts before starting the engine, most often the problem lies either in the wiring or in the spark plugs . In cases where the motorcycle does not start well when cold, try opening the air intake on the filter, but if the ignition does not allow you to start the engine, most likely the problem lies in condensation on the spark plugs. The fact is that due to temperature changes, condensation can form in the fuel system, which leads to rapid oxidation of the contact on the spark plugs. A visual inspection of the spark plugs will allow you to assess their condition.

According to statistics, 30% of motorcycles do not start without prior maintenance. At the same time, Soviet heavy motorcycles are more susceptible to frost and moisture, and problems most often arise with them when first started. Elements of the fuel system, in particular the carburetor, also remain sensitive. Metal parts oxidize due to low-quality gasoline, moisture remaining as a result of fuel combustion, and simply begin to jam. Blocked channels and improper operation of jets have characteristic signs - the engine runs unevenly, “coughs”, and stalls for no apparent reason even when the accelerator is pressed. Unfortunately, in some cases it is necessary to repair or clean the carburetor after inactivity. Car workshops most often do not undertake servicing of motorcycles, so you will have to look for a technician who understands your equipment.

The second most common problem is the lack of contact in the electrical circuit. The electrical system may suffer from oxidation at the wiring connections. It is worth checking all detachable connections at the terminals and contacts. Using special spray products that destroy the oxide film on the wiring may also help.

Reason and solution

The easiest way to get rid of pops on a carburetor motorcycle is to simply move the needle valve to a different position, changing the degree of saturation of the mixture with gasoline. It is better to entrust this operation to a specialist, since not everyone can fine-tune the carburetor. If there is electronic fuel injection, it is impossible to change the gasoline supply parameters yourself - the control unit will have to be flashed at a specialized service station.

It happens that the motorcycle shoots into the muffler and carburetor - this is often found on domestic Urals and imported choppers with a large cylinder capacity. The problem is a clogged air-fuel mixture at the inlet. To eliminate it, it is worth changing the filters and sealing gaskets, and also checking how tightly the pipes fit to the inlet fittings and whether there are any large cracks in them.

Read also: Standards for writing off fuel and lubricants 2018

Very often, popping noises appear after the muffler is replaced with a non-standard one or holes are cut out in it to eliminate resistance to the escaping exhaust gases. Particularly unpleasant sounds appear when installing a “direct flow”. The reason is the creation of a strong vacuum, which leads to a lean air-fuel mixture. Powerful imported motorcycles often use an exhaust gas afterburning system, which reduces their toxicity - after removing the standard muffler, its operation becomes clearly audible. To eliminate shots after changing the silencer, you must:

Reconfigure the carburetor or reflash the control unit;
Install filters with a different capacity;
Disable the exhaust gas afterburning system.

For engines whose engines operate at high speeds, the problem with shots may be associated with the speed limiter or crankshaft speed limiter. When a certain indicator is reached, the fuel supply may remain unchanged for some time, while the number of flares is reduced. Accordingly, a huge amount of gasoline enters the muffler, which explodes with a jerky sound, forming a “machine gun burst.” It can be heard especially well when releasing the gas after active acceleration. It is impossible to eliminate such a problem without reducing the life of the engine - you have to change your driving style so as not to irritate yourself and others with unpleasant loud bangs.

It is worth paying attention - skipping flashes may be due to its malfunction. Carefully inspect the high-voltage wires - there should be no cracks or peeling of the insulation on them. After unscrewing the spark plugs, check to see if there is a specific deposit on their surface that appears when using low-quality gasoline or when the ignition timing is set incorrectly. If the motorcycle is equipped with an electronic ignition system, the problem can often be solved by reprogramming the control unit. Some motorcycle owners decide to make drastic changes by installing a new control unit with preset sport settings - this solves the problem of shots in the muffler, and also increases engine power and improves dynamic characteristics.

First start

After a long period of inactivity, the motorcycle needs proper maintenance before the first start. In order to understand why a motorcycle does not start after winter, you need to remember the sequence of preserving your bike after the end of the season.

The first thing that is usually done in preparing a vehicle for long-term storage without movement is to remove the battery . It must be stored in a cool place, in a charged state. Therefore, to start the new season, you will need to install the battery in place. Sometimes a motorcycle does not start after winter precisely because of the lack of charge in the battery. Before installing the battery in place, it may need to be recharged.

It is important to store the motorcycle with a full tank of gasoline, otherwise condensation may cause metal corrosion. Contrary to widespread misconception, gasoline in the tank does not deteriorate, and this cannot be the reason why a Ural or Honda motorcycle does not start.

In any case, before starting to drive, you must carefully check the presence of antifreeze, brake fluid, and change the oil. Brake fluid is very sensitive to environmental humidity. If there are leaky connections, it absorbs moisture, which leads to oxidation of the brake system, and in some cases, to brake failure. And remember, your haste or inattention can cause serious damage to your motorcycle, especially after a long period of inactivity.

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Reasons why the scooter does not start when cold

Every scooter owner may encounter this problem: a pre-heated engine will work normally, but the scooter will not start in cold weather. Making a launch becomes extremely labor-intensive, or even impossible.

If the scooter doesn’t start well when cold, and you can’t do it with either the kickstarter or the electric starter, then it’s a consequence of problems with the power supply or ignition system. Each malfunction requires special attention, so we advise you to follow the instructions in this article.

Based on the identified problem, troubleshooting a scooter in cold weather takes from a few minutes to a couple of hours.

There is no spark in the spark plug

The moped does not start well when cold due to the lack of a spark in the spark plug. To resolve the problem, you must do the following:

Other possible reasons for the lack of spark after inspecting the spark plug

If your Alpha Moped does not start, find out the possible reasons and further steps to action.

Oxidation of contacts

The appearance of the spark plug may correspond to the norm, but the spark still does not appear, which means that a discharge test needs to be done. If there is no spark again, then test the scooter’s electronics for contact oxidation.

No spark on the wire

This may be a consequence of current leakage phenomenon. It is when a metal part of the moped comes into contact with an exposed high voltage wire. The conductor may have been water, which could have accumulated in the area of exposure during active trips through puddles.

You need to carefully inspect the wires running from the spark plug to the ignition coil, and if you do not find any disconnection or damage, then you can assume a critical breakdown in the ignition system:

Each of these parts causes a lack of spark and intermittent operation of the engine, so before you buy anything, find out what exactly is wrong and try to borrow a working part to check from your friend.

For many motorcycles, a malfunction - the scooter does not start well - is detected and corrected immediately in the first stages and the engine starts properly, otherwise you should look for problems further.

Important! It is better to stay as far as possible from the spark plug hole at the top of the cylinder, because fuel may splash out and ignite from that place.

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Author: Ruslan Solikamsk (5.141.229.—) Date: 08-02-17 22:29
Tell me what could be the reason? Suzuki DF15 starts even when warmed up only with choke + a little gas. After starting it with half a turn, it starts to choke, you immediately remove the choke and the speed is sharply restored. It starts occasionally without any choke. But if it doesn’t start right away, there’s no use in oiling it. Of course, it’s most likely the carburetor, but where exactly should I look? Cleaning was done. The carbon on the spark plugs is good.

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Author: Mikh@ (—.pppoe.irtel.ru) Date: 08-02-17 23:20
Check the compression on cold and hot, usually the problem lies in the valves, carbon deposits, clearance, etc. If there is a difference in compression, I would get in and measure the clearances on the valves; they go away when carbon deposits are deposited.

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Author: Mikh@ (—.pppoe.irtel.ru) Date: 08-02-17 23:58
Why are you fooling people, from the manual, compression in cylinders with a decompressor system is 8.2-12.2 kg/cm2

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Author: deniss Р80-48АА (—.84.nat.atknet.ru) Date: 09-02-17 00:08
I have a new walk-behind tractor that starts like this until you pull the choke, damn, I just pulled it out the first time, at least it’s cold hot, well, I’m not interested in whether he likes it or not, it’s not difficult for me to click the lever,

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Author: Mikh@ (—.pppoe.irtel.ru) Date: 09-02-17 00:08
Or damn, in the manual the transfers were placed incorrectly, decompressors should reduce the compression, 5.5-8.5, then the compression is normal. Yes, there is an air leak somewhere, or a carburetor, check the quality of the mixture...

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Author: Ruslan Solikamsk (5.141.229.—) Date: 09-02-17 00:17
I noticed that the carburetor gasket with the intake manifold had a corner broken off a little, maybe there is an air leak there, I’ll take a closer look at this place.

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Author: Archie (176.108.140.—) Date: 09-02-17 00:58
If there is a small suction, then it can greatly lean the mixture at low speeds when the engine is started by the starter. When the engine has already started, there is enough vacuum to suck fuel from the carburetor. But at medium and high speeds, a small suction behind the throttle may not have any effect, especially since there is only one carb, as I understand it.

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Author: Baha (—.aldems.lv) Date: 09-02-17 15:51
a friend’s Mariner 5 or 4 4t does not start without a choke, either cold or hot. scored. starts with a choke. and so the motor works without problems.

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Author: naemnik (80.73.70.—) Date: 09-02-17 17:31
On a Honda 2.5, only it wouldn’t start at all, adjusting the valves solved the problem.

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Effect of cold weather

The reason why the scooter does not start in cold weather may be a problem with the spark plug cap or its connector. In such a case, the cap is disconnected and the wire is brought a couple of millimeters closer to the metal element of the engine to rotate the crankshaft.

Vehicles in sub-zero temperatures are capable of passing current due to the contact of metal parts with exposed wires, as a result of which the scooter has difficulty starting in cold weather.

Failure in the power system

If you have already tested the occurrence of a spark and the performance of the ignition system, then the reason why the scooter does not start when cold may be hidden in a malfunction in the power system. This may mean either an excessive amount of gasoline supplied or a lack of it. The first thing you need to pay attention to is the following elements: fuel valve, gas tank, starting enrichment and gasoline pump.

Older models have a fuel tap directly under the gas tank. You need to disconnect the carburetor hose and open the tap, and then if the tank is completely full and gasoline flows out of the hose, then immediately begin inspecting the carburetor. If gasoline does not flow out, then the fault may be in the lines, or in the tap itself; you need to inspect them.

You might be interested in how to make an ATV with your own hands. A detailed description of creating off-road equipment from a motorcycle or car!

In new models, the fuel tap is automatic, operating due to vacuum. The fuel tank here is mounted above the carburetor, and the valve is a device consisting of a membrane, which often fails due to contamination and other things. This type of tap cannot be repaired and requires replacement.

To test the starter enricher, remove it and connect it to a 12v battery. Observe the needle; if it is working, it should smoothly exit the body; if this does not happen, it is faulty.

If all of the above elements are fully operational, proceed to disassembling the carburetor and cleaning it.

If you are experiencing difficulties with repairs, do not refuse the help of friends or contact technical service. It is better to entrust the matter to specialists than to buy unnecessary parts and spoil the existing ones.

Reasons why the scooter does not start when cold

It’s nice when the engine of a four-stroke scooter works “like a clock” and does not cause any trouble to its owner. But basically this only happens when the unit is warm. As soon as the two-wheeled “minibike” sits in the cold for a while, that’s it – there’s no way to start it when it’s cold. And you can't make it purr either from the starter or using the foot. So why does it happen that a four-stroke scooter does not start? The most common problems are in the ignition and fuel supply systems. More on this below.

Diagnosing a candle

The first step is to conduct a visual inspection of the spark plug. Unscrew it and look carefully to see if there are any mechanical damages or defects associated with melting. If any of this is present, then the spark plug should be replaced. In addition, moisture could get on it. To verify this, you need to remove the ignition element from the cap and let it dry. You can even do this over a gas one.

Quite often you can see cases when the owner is faced with the following problem: the scooter will not start. This may be due to a large number of reasons. Most often these are typical breakdowns or malfunctions, especially if the moped was parked in cold weather. Depending on the identified problem, the moped can be repaired in a few minutes or several hours.

Typical reasons

First of all, you need to check: the ignition and power systems. Carry out a check in those places that can cause the moped to move. The reasons why the scooter does not start, especially in cold weather, may be the following:

No spark in spark plug

The scooter does not start because there is no spark in the spark plug. In this case, you need to do the following: the spark plug is unscrewed and checked for suitability. Connects to the ignition coil using a wire.

Popping sounds in the scooter carburetor - the main reasons

You can often notice popping noises coming from the carburetor, which may indicate a violation of the mixture formation and some problems with ignition. In any case, for normal operation of the scooter engine, the problem must be eliminated. Let's look at all the reasons in more detail.

Why do popping noises appear in a scooter carburetor?

So, we started the scooter, started adding gas and heard popping noises in the carburetor. Note that we are not talking about the exhaust pipe.

Popping noises in a scooter's carburetor usually indicate a lean mixture. Why did the mixture become lean suddenly, with the engine running normally? There may also be two reasons for this.

The first, and most common, is clogging of the carburetor, as a result of which air is supplied in the same amount, but much less gasoline, since the channel or nozzle is already blocked, although not completely, but still. Testing this theory is quite simple: close the inlet of the air filter by half the diameter. If after this the claps stop or become less intrusive, the reason for the depletion is obvious.

Another reason for a lean mixture in this case is air leaks. Additional air can pass through the connection of the pipe with the carburetor and damage the integrity of the pipe or filter. This theory is tested in the same way as with a clogged carburetor, the effect is the same.
The second reason for popping noises in a scooter’s carburetor is early ignition. Since the ignition on modern scooters is not regulated, this phenomenon is extremely rare, but it still occurs.

Knowing these main causes of popping noises in a scooter’s carburetor, you can correct the breakdown in a timely manner and prevent further malfunctions due to a lean mixture. And this, as a rule, means overheating of the engine and much more serious malfunctions, including jamming of the piston in the cylinder.

You can also read other articles on the topic:

The problem is common! The carbs are K-68u. This is why the right cylinder shoots into the carburetor. But the shooting is strange! You give it gas, it seems like it’s not noticeable, it rips, it works, but if you put it on the foot and engage 4th gear, pick up a speed of 50-40 km/h, approximately, turning off the right pot, the left one works like clockwork without interruption, and when the left one takes off the candlestick , then the right one starts shooting at the carb, but trying to gain speed and the pops are not strong, but because of this it doesn’t pick up speed right away, and it turns out that at the beginning when you accelerate, not much resonance is created, but at traction and at speed it is, of course, very good you can feel it! I tried the ignition, it doesn't help! Valves are adjusted! But I didn’t check for them to pass through! I tried setting the jets to 125 and 165, no change! I changed the diffuser tubes from 165 to 178! The needle was raised and lowered! The fuel screw was changed (screwed in, unscrewed). Write.

More precisely adjust the synchronization of the carburetors.

Instead of chewing the ignition, it would be logical to do something that has not yet been attempted, namely:

yes, I will need to unhook the cradle to remove the head and immediately change the head gasket! But not because of this. It’s better to ask who has encountered it))))

and synchronicity. I can’t achieve synchronization because it shoots into the carb.

Then think about what might cause the shooting, you are closer there. Put back all the old jets that you removed. The caburators must be the same.

Why the scooter doesn’t start well when cold, let’s figure it out together

For many owners, a four-stroke scooter is a faithful assistant that can be used at any time of the year. Therefore, you can often encounter a problem when the scooter does not start well when cold or does not want to start in winter. This is due to a number of reasons that can be eliminated on your own. Most often, the problem lies in the ignition system, the power supply system may be malfunctioning, and air leaks cannot be ruled out, but this problem occurs somewhat less frequently. From this article you will learn how to identify and solve the problem, make the scooter start immediately and in any weather.

Typical reasons

Starting a scooter in cold weather may not always be possible due to various factors. First of all, you shouldn’t torture the equipment if it doesn’t start right away. Check the following:

Malfunctions in the power system

The power system may be to blame; If the piston group of the engine is working properly, then you should check whether gasoline enters the combustion chamber or not. This is easy to check: unscrew the spark plug and inspect it; if it is wet, it means gasoline is flowing. If it’s dry, we start checking with the gas tank: first, you need to find out if there is gasoline in there. If there is, check whether the tap is open. If everything is open, you need to remove the vacuum hose and clean it with air.

If everything is in order, move on to the carburetor float chamber. The bottom of the device is removed; it is usually held on by bolts. It contains a float. If the chamber is full, but gasoline does not flow to the cylinder, the nozzle is most likely clogged. You will need to pull out the needle, remove debris, dust, and all foreign particles. You can also check the scooter's petal valve: it is located below the carburetor. The petals may be damaged, causing the scooter to not start even if it is new. If the petals are not closed tightly enough, the valve must be replaced. In some cases, you can bend the petals with your fingers, but this measure will only help for a short time - only to start the scooter several times and ride it for parts.

In case of serious damage, you should check the piston, whether it gives the required compression ratio, the seals of the piston system, the CPG and the ignition system. But these reasons are more likely characteristic of old equipment that was not properly cared for.

No spark in spark plug

First of all, you should check the spark plugs if the moped does not want to start.

Attention! The procedure must be carried out carefully, without touching the scooter frame or other metal objects with your bare hands, otherwise you will get an electric shock.

If there is a spark and its color is yellow, then you need to install a new spark plug; yours is no longer suitable for use. A normal spark is blue and flows continuously.

If the coil is new, as are the spark plugs, but there is no spark, it is still worth checking the following:

What could go wrong

Ignition - no spark, the spark is weak, or it comes out “every once.”
Gasoline supply - fuel is not supplied to the combustion chamber or is supplied in insufficient or excess quantities, does not enter the carburetor or injector, the quality of the fuel does not meet the standard.
Air supply - the air filter is clogged, the damper adjustment is incorrect, the air filter housing is damaged, the intake pipe is “sucking”, the filter filling is missing.

Diagnostics will help to find out the cause of the breakdown.

Checking Basic Systems

In order to understand why the scooter does not start, the problem must be looked for sequentially:

Supply system

After checking the electrics and making sure that everything is in order, you should get to the power system: if the fuel is supplied in the wrong amount, the scooter may not start. If there is a large amount of fuel, the carburetor overflows and the spark plug becomes wet, and if there is little fuel, there is not enough of it for the piston to move. To do this, you need to adjust the jet, floats and needle, moving the limiter on it. It wouldn't hurt to check the gasoline pump either: sometimes it simply fails, so the fuel doesn't go anywhere.

Ignition system

The entire ignition system must be checked if there was a spark and then disappeared. If the spark plug and coil are normal, but there is still no spark, you will have to check more thoroughly. The coil, generator winding, and switch come under suspicion. A multimeter can check all this: for example, they test a generator like this - one probe is connected to the engine crankcase, the second to the generator sensor.

The resistance of a working sensor is 500 Ohms. If the value is higher, the winding is faulty; if it is below 200 Ohms, the problem is in the coil.

A cold scooter (moped) engine does not start - looking for the reason

In this case, the problem usually lies in the ignition system or in the power system. Both breakdowns require serious attention and adherence to clear instructions, which I will describe below.

Since most often the problem lies in the ignition system, we will consider this point in more detail. After that, let's move on to the power system.

The scooter does not start due to problems in the ignition system.

To begin with, we unscrew the spark plug and examine the electrodes; if they are melted or have any defects, we replace the spark plug with a new one.

If the candle is wet, be sure to remove it from the cap and dry it, for example, I do this on a gas stove. Now insert it back into the cap and check for a spark.

How to check for a spark on a scooter, the scooter will not start due to problems with the spark plugs

To do this, you need to place a spark plug on an unpainted part of the engine, usually the cylinder, and crank the crankshaft using an electric starter or kick. Before doing this, do not forget to turn on the ignition of the scooter. You should not check the spark with your bare hands; you should definitely protect yourself with special thick rubber gloves or a piece of rubber.

Another point to consider is that the spark plug must be kept away from the spark plug hole in the cylinder head, as gasoline may splash out from there and ignite. This has not happened in my practice, but the recommendations should not be neglected.

When the crankshaft is cranked sharply, a blue spark should run through the spark plug, quite powerful and constant. If there is no spark, or it is yellow and appears occasionally, first of all, we take it as faulty and check the spark in the same way on a new spark plug. As a rule, in more than half of the cases, at this stage the problem is solved and the scooter works properly. That is why it is so important to always have a working spare spark plug with you, which will always save you on the road in such a situation.

If, after you installed a new spark plug, the problem remains, we look for a known faulty place further:

The scooter will not start due to a faulty spark plug cap or connection to it.

Crank the crankshaft and pay attention to the end of the wire; a spark should jump between it and the engine (do not forget that we do all this with the ignition on). If a spark appears, you can breathe a sigh of relief. We examine the spark plug cap, if it is wet (and often because of this the normal spark disappears), then we dry it with a hairdryer, replace the spark plug and check the spark. No changes? Then we replace the cap with a new one and go.

Now consider the option in which there is no spark even on the wire .

This phenomenon can occur due to the so-called current leakage. The essence of this phenomenon is that any exposed section of the high-voltage wire touches the metal part of the scooter. This may not happen directly, and the role of a conductor can be played by water that accumulates in the area of the bare area when driving through puddles.

Examine carefully the wire running from the spark plug to the ignition coil; if you do not find any disconnections or damage, then you can assume more serious damage to the ignition system, namely:

Any of these elements, if faulty, can cause a lack of spark or unstable operation of the scooter engine. You shouldn’t buy them right away; it’s important to determine which electrical appliance is faulty. To do this, for example, you can borrow exactly the same one from a friend for testing.

The scooter does not start due to problems in the power system.

You should pay attention to this point first of all if you have a spark on your scooter and there are no problems in the ignition system.

Difficulty starting the engine, if considered only within the framework of the power system, will arise either from a lack of fuel or from its excess.

On older mopeds, such as “Karpaty” and others, the fuel tap is installed immediately at the bottom of the tank. Disconnect the hose from the carburetor and open the tap; if gasoline begins to flow out of the hose, skip this step and turn all your attention to the carburetor. If gasoline does not flow, although there is some in the tank, then the problem is either in the tap itself or in the line, we’ll take a look and see.

Modern scooters and mopeds have an automatic fuel tap, which operates due to vacuum. A striking example of such scooters are Yamaha and Suzuki equipment, as well as similar Chinese scooters. Here the gas tank is installed above the carburetor, and the role of the tap is performed by a small membrane-based device. Sometimes it is this membrane that can fail due to contamination and other factors. This type of fuel tap cannot be repaired, and if it fails, it must be replaced.

On Honda scooters, generally, the gas tank is located below the carburetor, and fuel is supplied to it by a fuel pump. In this case, of course, the above fuel taps are absent, since they are simply not necessary. It is very simple to check the operation of the fuel pump, disconnect the gasoline supply hose to the carburetor and pump the crankshaft with a kick or electric starter, the gas pump should produce fuel and gasoline will begin to pour out of the hose.

Since we are considering problems with starting the engine of a scooter and moped “in the cold”, and the starting enrichment is responsible for this start, you should definitely check it too. To briefly describe the operation of the enricher, the essence is that a cold engine requires more fuel to start and operate stable. This is precisely the function that the starting enrichment performs. A special needle opens an additional channel and slightly more fuel enters the carburetor than usual. Initially, the needle is in the retracted position. Inside the starting enricher there is a heat element, which, when heated, pushes out the needle and closes the channel.

If the starting enrichment is faulty, then enough fuel for normal starting does not flow into the carburetor, and of course starting problems arise. To check the enricher, remove it and connect it to a 12V voltage; after some time, the needle should smoothly come out of the body a few millimeters; if this does not happen, it is faulty.

If all the channels are clean and there are no problems in the fuel tap, as well as in the fuel pump and enricher, we proceed to disassembling the carburetor and thoroughly washing it. How to do this has already been described in previous articles.

It should be noted that difficulties with starting a cold engine also arise when the piston is worn out, so in this case it would be a good idea to check the compression, especially if your scooter or moped has traveled more than one thousand kilometers.

If you have difficulty starting the engine, and all the above remedies did not help you, ask a question in the comments field, and we will try to solve the problem together. Good luck with the repair.

You can also read other articles on the topic:

Diagnostics

The normal operation of the internal combustion engine is hampered by two problems: “there is nothing to set on fire in time” and “there is nothing to set on fire”. Look for the source of trouble in two channels - the fuel supply and the spark supply.

Consistently identify the fault by elimination. If one node works, move on to the next one.

First, find out whether the instrument panel lights up, whether the electric starter works, and whether the sound of the relay is heard.

If the lamps do not light up or light up very dimly, the motorcycle does not respond to the key, the relay does not click - this means that the battery does not have enough charge, or there is no current flowing from it. Remove the battery, check the charge and condition of the terminals.

If your motorcycle is equipped with both an electric starter and a kickstarter, try starting the engine with a kick.

If you manage to start the motorcycle, it means your battery is simply dead. Or the problem is more serious - the contact group in the lock, the start-stop button on the steering wheel, or the electric starter itself is faulty.

If the electric starter turns vigorously, but the engine does not catch on, look for where the spark has gone, check the condition of the air filter and the fuel system settings.

Intake system

If your motorcycle does not start, proceed in the following sequence:

Check if there is gasoline in the tank. The low fuel level sensor may be faulty, so check visually.
Make sure the fortifier is in the correct position for the situation.
Check the flow of the fuel valve. To do this, remove the hose leading to the carburetor. If necessary, clean the sump and change the gasoline filter.
Open the air filter cover, remove the filter element, shake out the dust from it, and put it back in place. If the paper element gets wet, dry it.
Inspect the vent body, clamps and pipes for damage.
Check that the mechanical faucet hose is in place. If it is removed or damaged, gasoline will not flow in the required volume.

Gasoline supply

If the faucet flows fuel normally, check to see if sediment has accumulated in the carburetor float chamber. Open the drain hole, drain the contents, close it, and try to start the engine again.

To find out whether gasoline is entering the combustion chamber itself, you will need a spark plug wrench. Remove the armor wire from the spark plug, open the tap and operate the starter, then unscrew the spark plug and inspect the insulator. If it is dry, there is a problem with the fuel supply. A wet spark plug will need to be dried before screwing it back in.

Ignition

Inspect the high voltage wire and cap for damage, check the reliability of contact at the coil terminal, and check that the cap is seated on the spark plug.
If the contact is broken due to vibration, it is enough to return it to its place. In the event of an internal breakdown, this will not help; the wire must be replaced. You can check for the presence of a spark in a simple way: unscrew the spark plug - with the contact in the cap, with the body - on the ground (cylinder). In this case, be sure to ensure reliable continuous contact of the housing with the metal, otherwise parts of the electrical equipment may be damaged. Touch only insulated parts or wear non-conductive, dry gloves.

The quality of the mixture can be judged by the color of the carbon deposits on the spark plug insulator:

black velvety – too much gasoline, incomplete combustion of the mixture;
black oily – too much oil in the mixture (for a 2-stroke engine), an unnecessary component (for a 4-stroke engine);
white or gray coating – lack of gasoline in the mixture;
velvety brown is the norm.

Even when “in the air” a candle vigorously produces a powerful flash, this does not mean that it is working properly. In the combustion chamber, the same spark plug can generate a weak spark that is unable to “break through” the gap between the electrodes. To be sure, replace the spark plugs. If after this a spark does not appear, change the coil or switch (ignition control unit). If it turns out that the spark is weak due to a weak battery charge, it makes sense to “ring” the generator.

Fuel quality

Normal operation of the internal combustion engine depends on the quality of gasoline.
Moreover, when “hot” the engine is less susceptible to this factor, but “when cold” it may not start at all. If your motorcycle does not start after a recent refueling, you may have been given poor quality fuel. If you refueled from a canister, condensation, rust particles or sand could get into the tank along with gasoline.

To correct the situation, drain low-quality gasoline from the fuel tank and carburetor. With injection engines it is more difficult - in order to drain fuel from the tank, you may have to remove the fuel module. This way, low-quality fuel will not pass through the pump and fine filter.

If you don't know how to get to the spark plugs or carburetor, don't torture yourself and your motorcycle in vain. Contact the professionals: call a field service specialist or call a motorcycle tow truck.

A cold scooter (moped) engine does not start - looking for the reason

You can often encounter a situation where a warm scooter engine works fine, but when it’s cold, problems arise and starting it becomes extremely difficult, and in some cases, impossible. However, you will not be able to start the scooter using either an electric starter or a kickstarter. In this case, the problem usually lies in the ignition system or in the power system. Both breakdowns require serious attention and adherence to clear instructions, which I will describe below. Since most often the problem lies in the ignition system, we will consider this point in more detail. After that, let's move on to the power system.

The scooter does not start due to problems in the ignition system.

To begin with, we unscrew the spark plug and examine the electrodes; if they are melted or have any defects, we replace the spark plug with a new one. If the candle is wet, be sure to remove it from the cap and dry it, for example, I do this on a gas stove. Now insert it back into the cap and check for a spark. How to check for a spark on a scooter, the scooter will not start due to problems with the spark plugs. To do this, you need to attach a spark plug to an unpainted part of the engine, usually to the cylinder, and crank the crankshaft using an electric starter or kick. Before doing this, do not forget to turn on the ignition of the scooter. You should not check the spark with your bare hands; you should definitely protect yourself with special thick rubber gloves or a piece of rubber. Another point to consider is that the spark plug must be kept away from the spark plug hole in the cylinder head, as gasoline may splash out from there and ignite. This has not happened in my practice, but the recommendations should not be neglected. When the crankshaft is cranked sharply, a blue spark should run through the spark plug, quite powerful and constant. If there is no spark, or it is yellow and appears occasionally, first of all, we take it as faulty and check the spark in the same way on a new spark plug. As a rule, in more than half of the cases, at this stage the problem is solved and the scooter works properly. That is why it is so important to always have a working spare spark plug with you, which will always save you on the road in such a situation. If, after you installed a new spark plug, the problem remains, we look further for the obviously faulty place: The scooter will not start due to a faulty spark plug cap or connection to it.

It also happens that the cap may not be in sufficiently tight contact with the high-voltage wire. To exclude this from the possible causes of the malfunction, we must check it. We unscrew the cap from the wire and bring the wire 2-3 mm to the metal part of the engine. Please note that if, in the case of a spark plug, we pressed it against the engine, then in this case the specified distance must be maintained. Crank the crankshaft and pay attention to the end of the wire; a spark should jump between it and the engine (do not forget that we do all this with the ignition on). If a spark appears, you can breathe a sigh of relief. We examine the spark plug cap, if it is wet (and often because of this the normal spark disappears), then we dry it with a hairdryer, replace the spark plug and check the spark. No changes? Then we replace the cap with a new one and go. Now consider the option in which there is no spark even on the wire. This phenomenon can occur due to the so-called current leakage. The essence of this phenomenon is that any exposed section of the high-voltage wire touches the metal part of the scooter. This may not happen directly, and the role of a conductor can be played by water that accumulates in the area of the bare area when driving through puddles. Examine carefully the wire running from the spark plug to the ignition coil; if no disconnection or damage is found, then we can assume more serious damage to the ignition system, namely: the ignition coil has failed; the ignition sensor (hall sensor) has failed; the switch is faulty; Any of these elements, if faulty, can cause a lack of spark or unstable operation of the scooter engine. You shouldn’t buy them right away; it’s important to determine which electrical appliance is faulty. To do this, for example, you can borrow exactly the same one from a friend for testing.

The scooter does not start due to problems in the power system.

Source

Messages [1 to 20 of 41]

kingdiamond7
passerby
Inactive

Registered: 06-05-2013
Messages: 9
Motorcycle: MT-9

Subject: Help me figure it out! Doesn't start when hot.

I can’t understand why the engine starts only with fresh spark plugs cleaned of carbon. I start it cold, it’s great, it just warms up, it’s impossible to start. The carbon is black. The coil, the wires are good. The spark plugs are new brisk a 17. The heads and piston are new. The ignition is modular. When I started running in a few Once the piston seized. Are the rings really stuck?
Edited by kingdiamond7 (06-05-2013 18:42:24)

on drakone
Elder
Inactive
Name: Albert

From: Omsk region. Omsk city
Registered: 07-12-2012
Messages: 4 972
Reputation: 125
Motorcycle: Ural 8.103.10, GAZ 31029

Re: Help me figure it out! Doesn't start when hot.

overheated or something. put the spark plugs hot and set the ignition, and there’s a lot of work in the carbs

kingdiamond7
passerby
Inactive

Registered: 06-05-2013
Messages: 9
Motorcycle: MT-9

Re: Help me figure it out! Doesn't start when hot.

What candles do you recommend?

mexanik62
Mechanic from the 30s.
Inactive
Name: Uncle Vitya

From: Evpatoria
Registered: 03-08-2011
Messages: 10 832
Reputation: 1 149
Motorcycle: 12-volt K-750, ZAZ Sens Hatchback

Re: Help me figure it out! Doesn't start when hot.

The spark plug gap is 0.65-0.7.
If the carbon deposits are greasy, the guides are most likely to blame. If it's dry, adjust the mixture lower at XX. Wash the air filter. The pistons are seizing, it may be a bit tight. ...nothing can stop this Soviet motorcycle, not even its own brakes...

Roma
Uralomaniac
Inactive
Name: Roman

From: Shentala, Samara region.
Registered: 23-10-2012
Messages: 6 151
Reputation: 517
Motorcycle: Ural IMZ 8.103-10

Re: Help me figure it out! Doesn't start when hot.

Guys, can the spark plugs get dirty because of shitty gasoline?
Knocked down - fight on your knees, if you can’t get up - attack while lying down!

mexanik62
Mechanic from the 30s.
Inactive
Name: Uncle Vitya

From: Evpatoria
Registered: 03-08-2011
Messages: 10 832
Reputation: 1 149
Motorcycle: 12-volt K-750, ZAZ Sens Hatchback

Re: Help me figure it out! Doesn't start when hot.

Maybe of course.
...nothing can stop this Soviet motorcycle, not even its own brakes...

kingdiamond7
passerby
Inactive

Registered: 06-05-2013
Messages: 9
Motorcycle: MT-9

Re: Help me figure it out! Doesn't start when hot.

The air filter is not installed since the engine is in tune. Who has heard of NGK B4H spark plugs? I pour fresh A 80 gasoline. The heads are new! I checked and ground the valves myself! The gaps are super. So I definitely rule out the head.
Added: 06-05-2013 17:28:10

Could it be because the rings are stuck that they are covered in oil? Black velvet carbon deposits!

Edited by kingdiamond7 (06-05-2013 21:23:23)

Roma
Uralomaniac
Inactive
Name: Roman

From: Shentala, Samara region.
Registered: 23-10-2012
Messages: 6 151
Reputation: 517
Motorcycle: Ural IMZ 8.103-10

Re: Help me figure it out! Doesn't start when hot.

Photo No. 2 is a typical example of a spark plug from an engine with high fuel consumption.
The central electrode is covered with velvety black soot. There are several reasons for this: a rich air-fuel mixture (improper adjustment of the carburetor, ignition timing or malfunction of the injection system), clogged air filter. Knocked down - fight on your knees, if you can’t get up - attack while lying down!

kingdiamond7
passerby
Inactive

Registered: 06-05-2013
Messages: 9
Motorcycle: MT-9

Re: Help me figure it out! Doesn't start when hot.

The motor sat for about 1.5 years. Maybe because of this?

Roma
Uralomaniac
Inactive
Name: Roman

From: Shentala, Samara region.
Registered: 23-10-2012
Messages: 6 151
Reputation: 517
Motorcycle: Ural IMZ 8.103-10

Re: Help me figure it out! Doesn't start when hot.

May be.
And who knows how it was used there before it was parked. Mine too, mileage 2600. New inside. And there were spark plugs with 3mm carbon deposits. Added: 06-05-2013 21:38:07

A velvety, matte black soot. Read here https://forum.motoroad.ru/topic3354-svec aniya.html

Knocked down - fight on your knees, if you can’t get up - attack while lying down!

kingdiamond7
passerby
Inactive

Registered: 06-05-2013
Messages: 9
Motorcycle: MT-9

Re: Help me figure it out! Doesn't start when hot.

Which cylinder is the ignition set to? I set it to the right. And in picture No. 2 it looks like it, but the picture also looks like 5.

solex
Experienced
Inactive
Name: Artem

From: Ukraine. Lugansk region.
Registered: 24-01-2012
Messages: 107
Reputation: 5
Motorcycle: Ural IMZ 8.103-40

Re: Help me figure it out! Doesn't start when hot.

The ignition can be set to any cylinder 3 mm before TDC.
if you have a cam (contact) check the gap on the cams 0.4-0.6, check, try to twist the quality of the mixture as mexanik62 wrote mexanik62 writes:

If it's dry, adjust the mixture leaner at XX

If you unscrew the screw, you make the mixture leaner; if you tighten it, it becomes richer. and by the way, normal gasoline is approximately light green in color as in the photo on the right

Roma
Uralomaniac
Inactive
Name: Roman

From: Shentala, Samara region.
Registered: 23-10-2012
Messages: 6 151
Reputation: 517
Motorcycle: Ural IMZ 8.103-10

Re: Help me figure it out! Doesn't start when hot.

At one gas station we have gas on the right, and at another on the left.
Right now in the Urals it’s flooded like the one on the left. Shit candles Knocked down - fight on your knees, you can’t get up - advance while lying down!

solex
Experienced
Inactive
Name: Artem

From: Ukraine. Lugansk region.
Registered: 24-01-2012
Messages: 107
Reputation: 5
Motorcycle: Ural IMZ 8.103-40

Re: Help me figure it out! Doesn't start when hot.

Added: 05/07/2013 06:05:47
Roma writes:

At one gas station we have gas on the right, and at another on the left. Right now in the Urals it’s flooded like the one on the left. Candles shit

Try changing the gas station

Edited by solex (07-05-2013 10:05:59)

on drakone
Elder
Inactive
Name: Albert

From: Omsk region. Omsk city
Registered: 07-12-2012
Messages: 4 972
Reputation: 125
Motorcycle: Ural 8.103.10, GAZ 31029

Re: Help me figure it out! Doesn't start when hot.

ai 80 is more towards yellow, ai92 is towards blue, and ai 95 is very blue

kingdiamond7
passerby
Inactive

Registered: 06-05-2013
Messages: 9
Motorcycle: MT-9

Re: Help me figure it out! Doesn't start when hot.

I would like to begin my greeting with words of gratitude! The problem was that the carburetors were incorrectly configured, namely, the needles were raised to the lower divisions. Plus, the quality screw was unscrewed too much. I installed A10B spark plugs, bought them from old stocks at the market, Soviet ones. Adjusted them and started them about half a dozen. I would never have thought that these were carbs. A huge hello to everyone from Ukraine!

on drakone
Elder
Inactive
Name: Albert

From: Omsk region. Omsk city
Registered: 07-12-2012
Messages: 4 972
Reputation: 125
Motorcycle: Ural 8.103.10, GAZ 31029

Re: Help me figure it out! Doesn't start when hot.

what about a10, I thought a11max

kingdiamond7
passerby
Inactive

Registered: 06-05-2013
Messages: 9
Motorcycle: MT-9

Re: Help me figure it out! Doesn't start when hot.

on drakone writes:

what about a10, I thought a11max

There were even A8b, but I didn’t find it.

solex
Experienced
Inactive
Name: Artem

From: Ukraine. Lugansk region.
Registered: 24-01-2012
Messages: 107
Reputation: 5
Motorcycle: Ural IMZ 8.103-40

Re: Help me figure it out! Doesn't start when hot.

well, for ours it’s generally better to A 14 or A 17

on drakone
Elder
Inactive
Name: Albert

From: Omsk region. Omsk city
Registered: 07-12-2012
Messages: 4 972
Reputation: 125
Motorcycle: Ural 8.103.10, GAZ 31029

Re: Help me figure it out! Doesn't start when hot.

no, 17 is already like a Lada, and there is the optimal temperature, and 14 is also not very good. somo norm is a11