What to do with a wet motorcycle spark plug?

What happens when your motorcycle's spark plug is wet?

The most common symptoms are spitting, poor performance, difficulty starting, or inability to start. Your motorcycle may also be flooded with fuel. If it is too wet, the spark will not be able to ignite the mixture and will end up fouling the spark plug. As a result, the motorcycle will not start or start.

This usually means the air/fuel mixture is too rich. Too much fuel (moisture) and the spark plug becomes fouled. A dirty wet plug will usually be black due to the rich mixture. This could easily be caused by incorrect settings, but this is not always the case. Common causes of a wet spark plug include the following:

Low compression
Cylinder head gasket disassembled
Wrong fuel
The starter is still there
The engine was flooded
Setting too rich

Hi all. We would like to share our project - installing a belt drive on a Honda CB400 instead of a chain drive.

The project began in the fall of 2022. It all started with the obvious - measurements on a motorcycle. The question was whether we could physically implement the belt without any “collective farm”. The main problem turned out to be the drive pulley. Our choice fell on a belt with a 14mm pitch (this pitch is used on Harleys). Having measured the space near the crankcase in the area of the drive sprocket, we realized that a pulley with 20 teeth, no more, would suit us. In the process of studying the catalogs of pulley manufacturers, it turned out that the minimum number of teeth for a 14mm pitch is 28 teeth, which naturally does not suit us. It was decided to draw a more than non-standard drive pulley from scratch with dimensions of 20 teeth and a pitch of 14mm. With the driven one, everything is simpler - a pulley with standard parameters of 56 teeth is built automatically in a special program. The gear ratio turned out to be 2.8 versus the standard 2.93. In the spring of 2022, the first version was already installed: both pulleys are made of aluminum (B95 alloy) on an erosion machine, a contitech industrial belt with a pitch of 14mm. As a result, it turned out to completely replace the chain with a belt without making any changes to the design of the motorcycle.

About 3000 km were covered on this version. During this time, the driving aluminum pulley wore out very intensively, its teeth became very thin, which caused the belt to wear out and fail - the sharpened edges of the pulley teeth literally gnawed and pulled out the belt teeth. About 6 teeth peeled off, but the motorcycle made it home on its own, but the driven pulley was practically free of wear. After analyzing the first version, it became clear that the following needs to be done: the drive pulley is made of steel and strengthened, and the driven aluminum pulley is cold anodized. All this was already clear by the middle of the 2022 season, then there were delays in manufacturing... As a result, we installed the second version in the fall of 2019: as planned, the drive pulley was made of steel and hardened to 45HRC, the driven pulley was treated with cold anodizing, and a new one was installed the belt, as in the first version, is contitech.

At the moment, about 2000 km have been covered on this version.

Now all that remains is to run the mileage on this version to find out its service life.

There are also plans to protect the lower branch of the belt in the area of the driven pulley.
short video after installing the latest version

What Causes a Wet Motorcycle Spark Plug and How to Fix It?

Now that you know the possible reasons why your motorcycle's spark plug is wet, it's time to figure out how to fix it. Let's look at each reason to determine the root of your problem.

You need to fix the problem so that you don't start replacing parts without knowing what the real problem is. It's better to do one thing at a time and check to confirm the repair. This can save you a lot of money and time in the long run.

First reason: compression problem

Low compression means the engine cannot compress the air/fuel mixture to burn it properly. Because the mixture cannot be fully compressed and ignited, some of the fuel does not burn.

This results in excess exhaust smoke, carbon buildup on the piston and exhaust port, and a wet spark plug.

Low compression is most often associated with high final wear. You can test the compression to see how it compares to the original. A more thorough inspection should be performed to determine what is worn on the top of the engine.

Wet motorcycle spark plug from a blown cylinder head gasket

If the cylinder head gasket blows, the spark plug may become wet. Coolant may leak into the cylinder and enter the air-fuel mixture. In this case, the engine fails and may produce a different sound. If your spark plug is wet, quickly check your coolant level. Low coolant levels could mean the head gasket has blown.

Head gasket available on Amazon

Bad fuel can wet your motorcycle's spark plug

Using unsuitable fuel or low-quality gasoline may cause the spark plug to become wet. Higher octane fuels, such as racing gasoline, will become richer over time and wet the spark plug if not adjusted correctly.

Use the manufacturer's recommended octane rating for your engine. A higher rating does not produce more power unless the compression ratio is higher than standard gasoline. Premium 91 octane gasoline is usually sufficient for most SUVs.

Poor fuel quality can also cause problems. Gasoline breaks down over time, breaking down and absorbing moisture from the air. It's better to use ethanol-free fuel because it will last longer before breaking down. Bad gas from a pumping station that is rarely used can also happen.

Fourth reason: the starter is still working

Everyone did it. Did you forget to turn off the throttle?

The throttle allows more fuel to enter the mixture, which is great for starting a cold engine, but the mixture will be too rich and perform poorly once the engine warms up. If your spark plug is wet, do a quick check to see if the throttle is working properly.

Starter available on Amazon

Spark plug is wet due to flooded engine

If the engine is flooded, the spark plug will definitely be wet. Engine flooding can occur when your motorcycle tips over if it is equipped with a carburetor, when it takes too much pushing to start the motorcycle, or when the engine stalls if the setting is too rich. To repair a flooded engine, turn off the gas, turn the motorcycle over to release excess gas, then let it sit for at least a few minutes to allow the gas to evaporate. You'll likely have to keep the throttle wide open to get the bike to start with a flooded engine.

How to replace a spark plug on a scooter

Checking the spark plugs is advisable when the engine operation is unstable - the scooter does not start well or begins to consume a lot of gasoline. By the appearance of the spark plugs, you can determine whether the fuel system is configured correctly or not, in particular, we are talking about the carburetor.

Attention!
If the diagnosis reveals that the spark plug is heavily soiled or damaged, it must be replaced. This item is inexpensive.

This process may seem simple, but in fact there are some nuances. So, if you don’t know them, there is a risk of breaking the thread in the spark plug hole. It is especially difficult for beginners, so it is important to listen to the recommendations of experts.

To make the replacement, you will need a 10mm socket wrench and a 21mm spark plug wrench or spark plug head. It is not difficult to get to the spark plug.

Replacement algorithm:

Open the seat.
Using a 10mm wrench, unscrew the 4 bolts securing the seat to the frame.
Remove the seat.
Pull the spark plug head off the spark plug by twisting it left and right.
Place the spark plug wrench on the spark plug. If the spark plug wrench is very long and rests against the frame, then it will not be possible to put it on the element that requires replacement. Therefore, it is advisable to replace the spark plug wrench with a 21 socket and an adjustable wrench.
Unscrew the spark plug counterclockwise.

Then you need to inspect the spark plug and replace it if necessary. In this case, the algorithm is reversed.

Eliminating the causes of the malfunction

If after performing the manipulations the scooter starts, that’s good, but you shouldn’t relax. Be sure to check for possible faults. What to do to prevent this situation from happening again:

Clean or replace the air filter. You can make sure that this is the reason by simply trying to start the engine with the filter installed and without it.
The air filter can be covered with a foam cover
Refuel only with high-quality fuel at trusted gas stations. After refueling at some stations, I had to clean the carburetor jets every time.
Check the condition of the spark plug. Pay attention to the gaps between the electrodes, the amount of carbon deposits and check the spark. The spark is checked as follows: a candle holder is put on the unscrewed spark plug, the thread is leaned against the cylinder and the engine is turned by the starter. In this case, the candle should give a powerful spark. If the spark is weak, adjust the gap; adjusting the gap does not help, change the spark plug. If the new spark plug produces a weak spark, then you need to pay attention to the ignition coil.
To check for a spark, place the spark plug against a metal housing and turn the starter
Read also: “Chekushki” from the Middle Kingdom: Chinese motorcycles 250 cm³
After checking the spark, check the gap between the electrodes
To check the gap between the electrodes, use special patterns

Advice! If the condition of your engine is far from new, then cleaning or even replacing the spark plug should be done more often.

Adjust the quality of the mixture. Set the carburetor mixture quality screw to the optimal position (where the quality screw is located, see this article), clean the carburetor on the moped. If you have a scooter with an injector, monitor the condition of the injectors. Use an injector or carburetor cleaner.
If you have a 4-stroke engine, pay attention to the valve adjustment. Incorrect release timing can also cause dirty spark plugs.
The battery should always be well charged and the starter in good working order. After all, candles are often filled in in winter, and in cold weather a reliable battery is required.
The quality of oil in the frosty season also affects the success of starting a scooter. The oil must be fresh and of the required viscosity for your local temperature.

Advice from experienced motorcyclists! If a spark plug is flooded, you should load the engine at high speeds at least once a week. This ensures that the cylinder and spark plug are purged from accumulated carbon deposits.

Advantages and disadvantages of belt drives on motorcycles

The advantages of belt drive include:

Unpretentiousness. The belt does not require special care; it is enough to periodically visually check for cracks and tears.
Compliance. Elastic rubber smoothes out all sudden changes in power, absorbs shock loads and thus ensures a smooth ride.
High efficiency. Losses when transmitting rotational motion from the engine to the wheel are minimal.
The belt drive does not create noise, which ensures a comfortable ride.
Durability. On average, a belt drive is designed for a mileage of 50 thousand kilometers.

However, with all the advantages, belt drive also has a number of disadvantages. You can start with the fact that the width of the belt does not allow it to be installed on sports motorcycles with a power of 110 kW or more. Protective covers around the transmission are mandatory, since if a foreign body gets into the belt, it will inevitably break. And motorcycles with covers are designed to be ridden only on asphalt.

Motorcycles generally use timing belts, and the rear pulley is made of aluminum coated with durable chrome. The chrome gradually wears away and, in the end, bare aluminum remains. As a result, the belt teeth begin to grind down, which leads to belt rupture. Therefore, along with the belt, the pulley also has to be changed. We should not forget about possible manufacturing defects, from which no production is insured. Both it and incorrect installation of the belt will lead to its rupture. The belt must always be at a certain tension - sagging will accelerate breakage. You can check the tension in any motorcycle workshop using a special device. Typically, sagging is allowed within two centimeters, but this figure is not a standard, it all depends on the individual characteristics of a particular model.

We are trying to start the engine

So, we figured out why the spark plug on the scooter floods. The repair methods and starting methods below apply to scooters with 2T and 4T engines.

The method is suitable if there is no tool. If you flooded the spark plug while trying to start the scooter, then give it time to stand for about 5 minutes. Then turn the gas handle all the way and turn the engine with the starter for about 10 seconds. You can use the foot several times if the starter is faulty. Release the throttle and try to start the engine again - it should work.
If you have a spark plug wrench, you should unscrew the spark plug and warm it up over a fire, after cleaning it from carbon deposits. With the spark plug removed, you should “blow out” the cylinder by rotating the engine with the starter or foot. Screw in the spark plug and try to start. If unsuccessful, the spark plugs should be replaced.
This is how you can heat a candle using a gas burner.

Advice! Although the first method is faster, it is still recommended to use the second. This cleaning of the ignition system will help avoid such problems for some time.

Alternative transmission options on motorcycles

A chain is the simplest, most reliable and common way to transmit torque to the rear wheel. The main disadvantage of chain transmission is that it requires constant maintenance. The chain has to be lubricated quite often, and the centrifugal force sprays the lubricant throughout the motorcycle from the gear side. Another disadvantage is the fragility of the chain - the operational period is no more than 20 thousand kilometers. But the chain confidently transmits high engine power, has small dimensions and easily passes dirt between the links - slush does not interfere with the operation of the transmission at all.

The cardan, unlike the chain, does not require careful maintenance, and since it is damaged extremely rarely, servicing is not difficult. Most often, such a transmission can be seen on touring motorcycles and on those intended for long trips. The disadvantage of the cardan is its heavy weight. This is the heaviest drive option and is therefore never used on sports motorcycles. The second significant drawback is the need for a driven bevel gear on the rear axle, which significantly increases the unsprung weight.