Questionhi i have a 1984 kdx200 with a honda ct125 engine in it. the problem is that when i start the bike the front sprocket will spin even in neutral and even with the clutch enguaged. when in neutral i can stop the sprocket spinning by just holding it. if i put it in 1st, 2nd, 3rd etc the sprocket will spin faster and i cannot stop it as it is too strong. every now and then it will stall if in a higher gear 3rd, 4th, 5th. it also feels like the clutch doesn't enguage when i pull it, it feels very weak (very easy to pull unlike other motorbikes i have ridden). any comments will be helpful thanks.
AnswerI think we need to clarify something first: The clutch is engaged when the lever is released and the springs push the plates together, allowing power from the engine to be transmitted to the transmission. When you pull the lever closer to the handlebar the clutch plates move apart and the clutch disengages the transmission from the engine.
I have no experience with dirt bikes, but I think it is safe to assume that a dirt bike's wet clutch should work the same way as a street bike's wet clutch. If you put a street bike on it's centrestand with the back wheel off the ground, the engine running and the transmission in neutral it is perfectly normal for the back wheel to turn, even with the clutch disengaged. You should be able to stop it easily.
The same thing will happen in gear with the clutch disengaged.
This is because the transmission and the clutch are in the engine oil. The oil makes the gears "stick" to the shafts and want to turn with them. Since the gears aren't actually engaged to the shafts it is easy to make them break free and stop turning with the shafts. The same goes for the clutch plates - they stick because of the oil but it is easy to break them free because they aren't pressed together.
Under normal circumstances, with the back wheel on the ground, the stickiness of the oil is easily overcome by the friction between the back wheel and the ground.
It is most noticable when the engine is cold because the cold oil is stickier. Some bikes even tend to lurch forward when the transmission is put in gear (with the clutch disengaged) until the oil warms up.
BTW: I do not recommend trying to stop the sprocket by hand, especially if the engine is in gear. This is an easy way to loose fingers.
Again, I can't speak with authority about dirtbikes, but Honda street bikes generally have much lighter clutch action than other makes. This is a good thing as it means that if you have to hold the lever in for a while or operate it frequently it won't tire you as much. It also makes smoother gear changes easier. I can pull the clutch lever of my CX650 based sidecar machine in with one finger.
If you can, compare your clutch's operation & feel to that of another CT125 to see if it feels the same.
It is also possible that your clutch springs are worn and need replacement. To find out you need to take the clutch springs out and compare their lengths with the minimum length specified in the shop manual.
Generally, though, if the clutch is adjusted as specified in the manual and the friction point is where it should be (about 1/4 of the lever's stroke in from where it starts to pull the cable) your clutch is probably OK.
You need to have the chain & back wheel on for this and sit on the bike with the engine running - the friction point is where the clutch just starts to engage and the bike tries to move forward as you slowly release the clutch lever (it should be the same point where the clutch disengages and the bike stops trying to move forward as you pull the lever in).
