Problems with "80cc" Clutch

[GearNut]

That cog is keyed to the shaft by a woodruff key, a small half moon shaped piece of metal that fits into a groove in the cog and a notch in the shaft. The woodruff key prevents the cog from slipping on the shaft. Yours is definitely slipping. Remove the cog and inspect the woodruff key. It may be missing from the assembly.

The gear is attached to the shaft by the large slotted screw you can see in the center of it. Behind the screw head is a toothed lock washer that is supposed to prevent the screw from coming loose. If the woodruff key is missing, the lock washer will have difficulty doing it's job as the cog will be spinning on the shaft.

The threads in the cog are there for the puller tool to thread into to facilitate cog removal.

 

[GearNut]

In posts 1 through 3 of Norm's clutch tutorial he demonstrates the removal of that cog and shows the parts involved in it's assembly.
http://motorbicycling.com/f4/bicycle-engine-clutch-222.html

The whole tutorial is about the clutch, but since that does not seem to be the problem, you do not have to follow the whole tutorial.

By the way, your gears look awfully dry and rusty. They should be well greased with a quality automotive high temperature grease.

 

[Halifaxcycles]

Thanks for the response GearNut, good tip on the grease! I'll let you know how it works out once I find a hand impact tool.

 

[KCvale]

http://motorbicycling.com/f4/clutch-cable-clutch-adjusting-procedures-22726.html

I added a bit to GearNuts new 'Clutch' topic ;-}

This may be a gear issue, but tough to tell.

 

[Halifaxcycles]

Found the problem! I was about to use my new hand impact tool that was ridiculously over priced for the one time I'll ever use it when I discovered the small cog is cracked. I still haven't "taken a whack at it" yet and I'm nervous to do so as I know little about it.

The small cog is cracked. Advice? Any recommendation for somewhere better then Zoombicycles to go for part, I'm in Canada so I suspect it's my best option.

The Other part of the matter is the tool cost half the price of a replacement engine..

 

[KCvale]

Found the problem!
The Other part of the matter is the tool cost half the price of a replacement engine..

Well, having another engine kit around to scavenge from is not a bad thing if you plan to build more than 1.

I know what you mean about tool costs though, even shopping at Freight Harbor with coupons it gets costly. I have probably spent more than I have netted on bike sales on tools so far.

 

[GearNut]

I recommend getting the gear from Zoombicycles. You will have a better chance of it fitting correctly as it most likely will have come from the same factory that made your engine.

 

[chainmaker]

Found the problem! I was about to use my new hand impact tool that was ridiculously over priced for the one time I'll ever use it when I discovered the small cog is cracked. I still haven't "taken a whack at it" yet and I'm nervous to do so as I know little about it.

The small cog is cracked. Advice? Any recommendation for somewhere better then Zoombicycles to go for part, I'm in Canada so I suspect it's my best option.

The Other part of the matter is the tool cost half the price of a replacement engine..

Im betting the same guy made our motors, same thing here cracked cog, just a hairline but it still works, I am waiting for a replacement. I bet the key is missing from yours as well. My guess is either the shaft was not finished enough and a bit too big, or the shaft hole was a little too small and whoever was assembling them had to tap it a bit too hard forcing the parts together resulting in the crack, and the key out . I bet there are a bunch of other engines waiting for this to happen to, due to incorrect or too great tolerances in the machining of parts. Thats why they are so affordable.


Cheers

 

[doyso]

God, I hate forums!

 

[Hg3223]

Hello any one can help me
I have fixed a few small problems already
New ngk spark plug
New spark plug cover
Fits like a glove and worked really well for a few days
N O W
When I engage the clutch rear wheel locks completely can't roll it backwards or forwards at all
I can lift the bike and turn the wheel by yanking!!! it
But noticed the small clutch doesn't turn??

 

[crassius]

first, take out the spark plug - if it doesn't turn now it is probably a chain problem

 

[Hg3223]

Spark plug out small clutch not turning and the back wheel locks chain fine bike not :.(

 

[2door]

Spark plug out small clutch not turning and the back wheel locks chain fine bike not :.(

I'm not understanding what you're saying here.
What are you calling "the small clutch"?

With the clutch 'engaged' (handlebar lever unsqueezed) the rear wheel will be hard to turn because you are fighting engine compression as well as drag from the gears, etc.

If the clutch is 'disengaged' (handlebar lever squeezed and cable adjusted correctly) the rear wheel should spin free. If it doesn't either the cable is too loose or the chain is bunched up on the engine drive sprocket. This is usually do to a chain that is too loose and/or misaligned sprockets.

Tom

 

[crassius]

take off drive cover & see if chain is jammed on sprocket

 

[Hg3223]

I wish it were that easy guys
Chain moves freely I can ride it around with the clutch disabled but as so as I engage it LOCKS
The small thing that's connects to the clutch won't turn at all (( Oo
Thats a picture The big O" the clutch the small o " is the thing thats Stuck locked seises to move I'm no mechanic
wish I new what its called

 

[Hg3223]

Small bevil ? That's locked

 

[Hg3223]

Got it going Did a bit of reading on pistons and how they work
Fixed it by only taking off three screws and turning a spanner twice haha ha
"Two weeks later"
Frustrating fun toys