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How to adjust valve clearances on a scooter?

How to adjust valve clearances on a scooter?
How to adjust valve clearances on a scooter?

Many four-stroke scooter owners know that valve clearances need to be adjusted. But due to inexperience and ignorance, they do not pay the necessary attention to this procedure. But in vain. By adjusting the valves on your engine, you will not only improve its stability, but also extend its life. It may seem that a few fractions of millimeters do not have much effect on the performance of the scooter.

However, practice shows that too small or too large valve clearances accelerate the wear of engine parts by several times, helping to reduce its operation time by several times. Let's answer the question of why this is happening.

Normal valve clearances for scooters (engine size 50-100 cm3) are about 0.05 mm. This value is the same for both the exhaust and intake valves. However, if it is increased, then the engine starts to knock. To the ear at idle, such engine operation is heard as the rumble of a sewing machine.

valve clearances

But that's not the trouble. Increased valve clearances shift the phasesgas distribution. Therefore, when the engine speed is added, the traction of the scooter decreases, fuel consumption and wear of the valve mechanism increases.

When valve clearances are greater than necessary, then the engine is in even more deplorable condition. After all, there is a loss of compression from the fact that the gaps, heating up, become even smaller, while slightly opening the valves. There is a breakthrough of gases and loss of power. The valve or its seat may also burn through.

valve clearances

After this trouble, the scooter generally ceases to move well. He loses power and candles turn black from soot. Therefore, there is nothing left to do but to replace the valves or even the entire head.

It is better to adjust the valve clearances on a scooter once every thousand kilometers than to buy new parts. To do this (for example, for Alpha and Delta), you need the following tools:

- set of keys;

- set of probes;

- pliers.

scooter valve clearances

But do not forget that the valves are adjusted when the engine is cold (when the air temperature is below zero, then it is warmed up a little). The work process is reduced to the following operations:

- Twisting the candle.

- Installing the piston at TDC (end of the compression stroke), thereby releasing the valves. To control this, it is necessary to unscrew the plug on the crankcase cover and, turning the crankshaft, ensure that the "T" mark is exactly in the middle of the hatch. Using the wrench, unscrew the plug and,turning the screw on the rocker arm, we make the adjustment. This operation must be done carefully so as not to damage the screw, which is most often plastic. They measure the gap with a probe, which, with a thickness of 0.04 mm, should pass freely, and at 0.06, it should not climb at all. The 0.05 mm probe should be difficult to enter.

- Screwing all plugs and candles back into place.

That's it. As you can see, there are no special secrets here. Now you can start and warm up the engine. With the correct adjustment, you will immediately determine by ear how quieter your scooter has become and how pleasant it is to ride.

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