Why is there a weak spark on a Ural motorcycle?

Why is there a weak spark on a motorcycle?

You should not immediately “blame” the ignition system for the malfunction. As practice shows, it fails and provokes the problem of a weak or irregular spark much less often than the wrong fuel mixture gets into the tank. Either too lean (for example, after a long period of inactivity), or too rich (if the fuel from the float chamber has managed to wet the cylinder).

First start

After a long period of inactivity, the motorcycle requires proper maintenance before starting for the first time. To understand why the bike does not start after winter, you need to remember the sequence of preserving the bike after the end of the season.

The first thing that is usually done in preparing a car for long-term storage without moving is to disassemble the battery. It must be stored in a cool and busy place. Therefore, before the start of the new season, it will be necessary to replace the battery. Sometimes the bike does not start after winter due to lack of battery charge. The battery may need to be recharged before replacing.

It is important to store the motorcycle with a full tank of gas, otherwise condensation may cause corrosion of the metal. Contrary to popular belief, the 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 you start driving, you must carefully check the presence of antifreeze, brake fluid, and change the oil. Brake fluid is very sensitive to environmental humidity. When connections are leaking, it absorbs moisture, which leads to oxidation of the brake system and, in some cases, brake failure. And remember, your haste or carelessness can cause serious damage to your motorcycle, especially after a long period of inactivity.

What are the reasons for the Ural motorcycle not starting?

Why is the Ural bike difficult to start? There are frequent breakdowns and ways to fix them. These bikes don't break down very often. But it happens that you have to completely redo the transport.

The first problem that occurs is that the bike will not start. Don't go to extremes right away. The likely cause is compression problems.

We pump gas into the chamber.
Turn on the ignition and start the bike.
We unscrew the candle. When it produces a consistent spark, it is in good condition.
We check the cylinder for leaks.

In the last step, plug the hole for the spark plug with your finger so that no air escapes. Air filters through your fingers - everything is fine with compression.

Read also: “Why Mars and not the Moon?”

conclusions

From the article you learned why there is no spark on a 4t scooter and the reasons for such a malfunction. The cost of repair work may vary depending on the cost of the parts, but it is always more profitable to do the work yourself. And now you know what to do if the spark suddenly disappears; what to pay attention to. Be careful when troubleshooting, pay attention to details, refer to reference books for accurate data. Only if all conditions are met will you succeed!

Source

Required Tools

Before you start adjusting the valves, you should prepare the necessary tools.
First of all, you will need a set of keys. In practice, you will only need one, but it is better to have everything on hand. The motorcycle valves are directly adjusted using feeler gauges. Depending on the motor model, different probes may be needed. On the M 72 Ural, a thickness of 0.1 mm will be required; for newer engines, for example, IMZ, it is better to use 0.05 mm.

In fact, these are very conditional indicators. There is a small tolerance during adjustment, but under operating conditions of the power unit this does not affect its performance.

You will need to stock up on a small container to catch the oil; it can sometimes spill. Also, a rag will not be superfluous; it can be used to clean the engine from dirt. Let's see how to properly perform this repair.

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After unscrewing the screws, remove the windings and sensor and inspect for damage. You can measure the resistance of the components and compare it with the recommended one without removing the cover. Remember, as a rule, the control unit receives a signal both from the sensor and from its winding, distributed over the stator power windings. Therefore, it can operate regardless of the functionality of the main power system (the engine can be started even without a battery).

What does the contactless ignition system on the Ural and Dnepr motorcycle provide?

No headaches for the motorcycle owner when operating it;
Starting the engine in wet and cold weather;
Failure-free operation of the ignition system;
Increased driving characteristics of the motorcycle as a whole;
Increased candle life;
Starting the engine when the battery voltage drops to 6 volts;
Constant, not changing over time, ignition timing;
The ignition coil cannot overheat.
Powerful, required color, sparking.

Carburetor problems

So, you are the owner of a Minsk motorcycle, the carburetor of which regularly receives gasoline, and the spark plug provides a spark sufficient for stable operation of the engine.

But this is not enough for the motorcycle to start. An unscrewed dry spark plug showed that the problem was in the carburetor, namely, the incoming fuel could not reach the combustion chamber of the cylinder. In this case, it is necessary to remove and clean the carburetor.

To clean the carburetor, it must be removed by disconnecting it from the cylinder and air filter. You also need to disconnect the throttle cable and gasoline hose. To prevent dirt from getting inside the carburetor, before further disassembly you must not be lazy and completely clean it.

It is necessary to disassemble and reassemble the carburetor cleanly, since dust or dirt particles getting inside will lead to unsatisfactory operation of the motorcycle engine even after washing it.

Upon completion of disassembling the carburetor, it is necessary to clean all its parts from accumulated dirt, and also blow out all channels and the jet with a compressor. It will not be superfluous if you additionally blow out the air filter and gas tap.

After completing all the manipulations, you need to install the carburetor in place. During assembly, as well as during disassembly, it is necessary that no dirt gets inside the carburetor.

After installation, make sure that the carburetor fits tightly to the cylinder. If you did everything correctly, you can be sure that after some effort your Minsk motorcycle will be able to start.

Replacing spark plugs before installing electronic ignition systems

Spark plugs are the last element of the spark generation system in any engine. They work under conditions of high pressure and temperature.

Sparking occurs on them when a high voltage pulse is applied. Therefore, it is not possible to test them, without a test bench, in domestic conditions.

The serviceability of a working spark plug can only be judged visually - by carbon deposits on its tip or presence on the “skirt”. To ensure reliable engine operation, change spark plugs according to the motorcycle operating rules, without expecting them to work forever.

Choose the correct heat rating when purchasing spark plugs. Set the gap in the spark plug electrodes to 0.7-0.8 mm.

We hope that these problems with the spark plugs are not observed and, after purchasing (manufacturing) a non-contact type ignition system and replacing the spark plugs, we begin adjustment work.

Leave it to mechanics or install electronics

Perhaps not all older motorcycle models are running. The Ural motorcycle sits and rusts in my grandfather’s barn because it won’t start.

The wheels are spinning, the engine is not jammed. Maybe the spark goes into the ground, as they say. In short, you need to look at the spark generation system. But even a working motorcycle, with a contact ignition system, causes unexpected and unpleasant problems for its owner:

won't start when you really need it;
with new oil rings in the engine, the spark plugs become covered with soot;
there is no required engine power when driving with maximum load;
the maximum speed is not reached;
The battery is slightly discharged and the engine does not start.

Tuning a Ural motorcycle with your own hands - this article will help you decide in which direction to modernize your Ural.

The contact ignition system creates a lot of problems, especially when the moving parts in it have already worn out, backlash has appeared, and the geometry of the elements has changed.

The solution is simple - all cam ignition is thrown out, a modern electronic non-contact type spark generation system is installed. You will no longer have to deal with the thankless task of cleaning contacts and endlessly adjusting the gaps in the breaker. All this is possible thanks to the simple, but quite reliable design of the motorcycle. For example, it is quite easy to set the thermal gap and adjust the valves in the Urals with your own hands, using only your own tools from the garage. This way you will gain valuable experience and save money on visiting the workshop.

No spark causes and solutions

When there is no spark after an unsuccessful attempt to start the engine, or the spark on the spark plugs suddenly disappears and, of course, the engine does not start, then some novice drivers do not know where to start to get rid of this malfunction. This article will describe the reasons why a spark may be absent or appear every once in a while, and will also discuss methods for simple diagnostics (troubleshooting) of the ignition system.

I have already written about repairing the ignition system and you can read about it in detail in this article. It describes in detail the testing of all components of the ignition system, both the modern contactless electronic and the more ancient contact ignition system.

But this article will describe when there is no spark, the reasons and specific actions to ensure that a spark appears on the spark plugs.

No spark causes and solutions.

1. Let's start with the simplest and gradually move on to more complex reasons. The first and most common reason is a discharged battery. Of course, this can be determined without a voltmeter, since a discharged battery will not crank the crankshaft with an electric starter of a car or motorcycle. But many drivers, after an unsuccessful attempt to start with an electric starter, try to start the car with a pusher, hoping that the energy of the discharged battery is not enough for the starter, but is quite enough for the ignition system. In most cases this is not the case.

And if the energy of a discharged battery for a contactless electronic ignition system in most cases is enough to cause a spark and a successful attempt to start the engine from the pusher, then for an older contact system, the energy of a discharged battery will not be enough to cause a spark (especially if the contacts are burnt, and this happens often) . Therefore, in order not to guess and not waste human energy on pushing the car, we simply bring the battery back to normal using a charger. Beginners can read how to properly charge the battery here.

2. Another simple and banal reason why there will be no spark on the spark plug is simply a failure of the spark plug or it is simply necessary to clean the spark plug (read how to check and properly clean the spark plug here). Of course, the spark plugs don’t all fail at once, and if one of the spark plugs fails, the four-cylinder engine will simply start to stall. Therefore, this reason is only suitable for single-cylinder motorcycle engines, but still it was worth mentioning, let’s move on.

But before checking and cleaning a non-working spark plug, try swapping the high-voltage wires and if a spark appears on a previously non-working spark plug, then the reason is not in the spark plug, but in the spark plug wire, which should be replaced.

3. The third reason for the loss of spark, which often happens on used cars and motorcycles, is there is no voltage at the ignition coil terminal after turning the ignition key. Using a tester set to voltmeter mode (measuring direct current), you should measure at the coil terminals whether a voltage of 12 - 13 volts is supplied to terminal B+ of the coil (see figure) when the ignition switch is turned on. If it doesn’t, then you should check the integrity of the wire going from the lock to the coil (or from the mounting block to the coil - GP wire in Figure 1), and also check whether the terminals are oxidized.
4. If voltage comes to terminal B+ of the coil after turning on the ignition switch, but there is still no spark, then you should check the integrity of the wire and the cleanliness of the terminals of the wire coming to the distributor from the coil (the black wire marked with the letter C in Figure 1) and in general check all the wires and terminals of the low-voltage circuit of the ignition system (check the wires marked with the letters G and K, as well as GC and K. It also wouldn’t hurt to check the operation of the ignition switch itself 8 and the ignition switch relay 7, which rarely fail but still fail. And of course, we check the integrity of the fuses responsible for these circuits (in general, I advise beginners to check all the fuses at the very beginning).
5. On a contactless electronic ignition system, use a voltmeter to check the presence of a voltage of 12 volts (after turning on the ignition switch) at terminal B+ of the ignition coil, as well as at terminal 4 of the switch and check the integrity of the wire marked with the letters GP in Figure 2. We also check the integrity of the wire and the cleanliness of terminals K of the coil and terminal 1 on the switch and the integrity of the control wire of the gearbox connecting them. We also check the integrity and reliability of the connection (cleanliness of the terminals) with the car body of the black wire marked with the letter H in Figure 2, which connects terminal 2 of the switch to the car body. What can happen on the car due to poor contact of a lot of other wires, I advise you to read this useful article.
6. Next, we check the integrity of the wires and the reliability of the connection between terminals 3, 5, and 6 of the switch and the Hall sensor (wires marked with the letters Z, P and BC in Figure 2). If the terminals are securely connected and not oxidized, and the wires are intact, then we check the functionality of the hall sensor itself (read how to do this here). Well, you can find out how to check the functionality of the switch and ignition coil by clicking on the very first link at the beginning of this article, in the article about repairing the ignition system).
7. Having checked the low-voltage circuit of the ignition system, as described above, if everything is in order and a spark has not appeared, then we check the high-voltage part of the system. If there is no spark on any spark plug, then first of all we check the central high-voltage wire G (see Fig. 2), connecting ignition coil 5 and distributor 1. The tips of this wire must be clean and must be tightly inserted into the mounting sockets of the distributor cover and the ignition coil . We check the wire itself for integrity using a tester set to ohmmeter mode.
8. If there is no spark on only one spark plug out of four, then we check the high-voltage wire of the non-working spark plug (you can swap the wires, as described above, or check the wire of the non-working spark plug using a tester). Also, having removed the distributor cover, we check it for integrity (there should not be even the slightest cracks) and the cleanliness of all contacts inside and outside the cover, and the integrity of the carbon (graphite cylinder) in the center of the cover.

Messages [1 to 20 of 34]

1↑ Topic from Uralchik 09/27/2014 18:27:13

Uralchik
Newbie
Inactive

Registered: 01-06-2014
Messages: 22

Topic: It's corny, but Ural won't start

Guys, the story is this: I started it, rode about 500 meters and the motorcycle stopped pulling itself (in a straight line), started shooting and sneezing. Well, you understand. Immediately thinking - sucking air. And sure enough, oil was oozing under the left cylinder head. There was an aluminum gasket, I replaced it with a paronite gasket. I set the valve clearances “by eye”, first setting them to TDC (arrow on the flywheel) and adjusting the left one, and then turning the right cylinder back to TDC. I haven’t come across tuning on two-cylinder ones, so I asked my friends how it was done, and then began to demonstrate. It seems that everything is set as before (the gaps feel the same), but the bastard won’t start! Once it grabbed once, roared at high speeds (for some reason, at high speeds) for about five seconds and died. It never started again, didn't even catch. The spark is excellent on both spark plugs, I didn’t touch the carburetors and ignition, as before the breakdown they were still standing, but before the breakdown the engine was flying, not driving

Tell me where to start poking around to understand what's going on?

Oh, I almost forgot to clarify, the battery is fresh, just from charging, unless the motorcycle was parked in the open air, where did the water get in?

Edited by Uralchik (27-09-2014 18:28:06)

2↑ Reply from RaaF37rus 09/27/2014 19:22:37

RaaF37rus
Pro
Inactive
Name: Sergey

From: Ivanovo region. Kamenka village
Registered: 27-07-2013
Messages: 568
Reputation: 66
Motorcycle: IMZ 8-103-10

Re: It’s corny, but the Ural won’t start

Well, it’s better to set the valves not according to the mark on the flywheel, but “when the intake starts to close, you adjust the exhaust, and when the exhaust starts to open, you adjust the intake.” Couldn’t you turn the camshaft? look.

3↑ Reply from Lerych 09/27/2014 19:47:12

lerich
MotoDealer
Inactive
Name: Valery

From: Yaroslavl region
Registered: 18-01-2012
Messages: 2 138
Reputation: 215
Motorcycle: Ural m66, Riga 22, Java 360, Ural 8.103

Re: It’s corny, but the Ural won’t start

so there could be a bunch of reasons. I didn’t touch the carburetors, but gasoline may not flow. from the same tank for example. I have about the same crap. it started and worked well, and then suddenly it won’t pull after 5 km. I took the carbs apart and gasped! there the dampers are not just worn out, but they are even chewed up, just on the cylinder, which barely plows. The tank was so clogged that I had to pierce the nipples that connect the compartments with a nail. The ignition tends to unscrew. The camshaft support has the same property, but the marks no longer match and the valve timing shifts. The valves are somehow strangely adjusted. As I understand it, if you set it according to the mark, then one cylinder and the second should be set at 180 degrees, and not according to the mark. Otherwise, all strokes will occur on both cylinders at the same moment, and this should not be the case.

4↑ Reply from Wild Hunter 09/27/2014 20:39:10

Wild Hunter
Moder
Inactive

From: Permyak
Registered: 16-05-2012
Messages: 6 897
Reputation: 610
Motorcycle: Dnepr MT 10-36, Ural M 67

Re: It’s corny, but the Ural won’t start

Set the valves as Seryoga said, check whether gasoline flows into the carb, then whether it flows into the cylinder, check whether the spark plugs are damp or not, check the oil level in one thing - I don’t like something that stopped pulling. Look at the ignition at least visually - recently it almost shattered to pieces, but it worked, I was tired of looking for the reason. And of course, the faucet needs to be cleaned at least sometimes.