Help cannot start the bike~~~

R

roozbeh

New Member
Hey, today I finished my 2-stroke 80cc/66cc motor build. However, the problem is when I try to start it. When the clutch is pulled back I can get pretty good speed with it however, when I release the clutch and engage the engine the rear wheel stops so suddenly that I cannot even pedal for more than half a second.

Any clue to what I can do?
 
Sounds like the motor has trouble turning over. Unscrew the spark plug and try to turn the engine over and look inside the chamber.. investigate. It's quite normal that these little engines have lots of compression and can be rough at low speeds.
 
Yea I don't think your supposed to be able to pedal with the clutch engaged... Your supposed to gain some speed or go down a slight hill to gain enough momentum to be able to engage the clutch and start it.

It's gonna take a while with a new engine, it took me a while to get started along with adjusting the idle screw.
 
No even when the spark plug is out, and the engine is engaged it is almost impossible to pedal/ spin the wheel.
 
Take the master link out of the engine drive chain, remove the chain from the rear sprocket and try to pedal. Maybe the binding is not the engine. Even if you have the clutch mis-adjusted, with the spark plug out you should be able to free pedal and feel only a little resistance.

Check your chain tension. A chain that is too loose can bunch up on the engine drive sprocket and bind. If this happens the rear wheel will not turn and forcing things can actually break the engine case.

To check for a seized engine, remove the left side magneto cover and using a socket or a wrench on the nut that holds the magneto rotor, see if the crankshaft will rotate.

Get back to us with your findings.
Tom
 
You got a problem then. It should be fairly easy to pedal with the spark plug out. Really easy actually. Sounds like you need to open her up and see what the problem is. Unfortunately while trying to start it up there is a chance something got really screwed up. If you don't trust your self to work on it you got two options, first (probable cheapest) look on this forum for top half tear down and go for it anyway. These things are probable the cheapest engines you can learn to do anything to and they are extremely simple. The second option would be find a local that would be willing to help you out. You could maybe take it into a small engine shop but they most likely wont have any replacement parts so you will probable still end up doing some of it yourself. Where did you buy the engine from? I think dax might be one of the only places with any kind of warranty but you might want to look into it.

Hopefully I am wrong and it is something easy.

Just had a afterthought. You are a little new so I am going to throw this out there. Don't be offended. Your chain isn't too loose and bunched up in the cover is it? (Does it roll right with the clutch pulled for a long time at high speeds?)
 
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Hhmm 2door I just spent 15 typing my previous post up and had one last thought that I decided to put down. Looks like you beat me to it. Haha Great minds think alike? ;)
 
2door said:
Take the master link out of the engine drive chain, remove the chain from the rear sprocket and try to pedal. Maybe the binding is not the engine. Even if you have the clutch mis-adjusted, with the spark plug out you should be able to free pedal and feel only a little resistance.

Check your chain tension. A chain that is too loose can bunch up on the engine drive sprocket and bind. If this happens the rear wheel will not turn and forcing things can actually break the engine case.

To check for a seized engine, remove the left side magneto cover and using a socket or a wrench on the nut that holds the magneto rotor, see if the crankshaft will rotate.

Get back to us with your findings.
Tom
Click to expand...

Follow these instructions....I couldn't express it any more clearer. Other then turn the nut clockwise so as it's not loosing it up. DO NOT FORCE the rotation of the nut. If it going to turn the engine over it will do it easily.
 
thanks guys I got the inside to unjam some nut was stuck in there (i think from manufaturing or something). However, now I run into this puzzler... when I got more than 5km/h the chain comes of the engine sprocket. And I also checked the engine sprocket and back tire sprocket are alligned. Any thoughts :/

thanks,
 
If your chain alignment is right on and the tension is correct then the best guess is that your rear sprocket is not centered on the hub. This is critical. It must be centered with no wobbles either horizontally or vertically.
Question: Are you using the kit supplied chain tensioner? Almost without exception they will not allow the chain to run true unless the tensioner bracket is twisted (bent) slightly to allow the wheel to align with the chain path. If the wheel is pulling the chain off to either side instead of centered on the rear sprocket it can cause your problem.
Let us know what you find.
Correct chain tension is to have 1/2 to 3/4" slack, no more or less.

I'm a little concerend with the "nut" you found jammed in someplace. Where was it and what did you take apart to find it?

Tom
 
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My money is on the chain tensioner not being aligned correctly. 9 times out of 10 you got to bend them to line up right. You also want about .5-.75 inches of play on the chain (vertical). If your sprocket is correctly lined up you are already 90% of the way there.

A lot of people really hate the stock chain tensioner and they have a point about it being dangerous. I run them. I can't find it now but I read a thread that was about ways to make them a little better/safer. Basically make sure it fits your bike well. You might need to flatten out the parts that clamp onto the bike tube or maybe even give them a little more of a curve (never heard of the later but anything is possible) I put a little bit of gorilla tape on the bar before I put it on there half as a paint saver half as a way to help keep it from moving. Once I have mine fitted correctly for the bike (takes about 15 min) then it will be on there solid enough that I will never HAVE to check it (I watch it obsessively though :D ). This is all to prove that the stock one can serve well but it takes some work. It will still never be as good as the custom ones that we all see around.
 
Agree here, the sprocket/chain is not lined up correctly. Could be the sprocket to sprocket, the tensioner, or the gears need to be beveled or a combination of all. I also run the stock tensioner, but as mentioned, it takes a little work to get it lined up correctly. This spring I'm going to redo it with one I bought of a member.

This is what I'm going to experiment with.


I'd sure like to know where the nut came from.
 
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