Jerky clutch

V

vincent713

New Member
Hello all,

Every time I cruise at a low speed, my engine or clutch seems to be very jerky, my whole bike jerks. Does anyone know how I can solve this problem? Any suggestions would be much appreciated.
 
How slow is your "low speed" ? If you go very slow, maybe eight to ten mph or less with the clutch engaged, jerking might occure. You can't downshift to a lower gear so at very low speeds you might have to disengage the clutch and pedal.
Can you be a little more specific at what speed you're having this problem?
Tom
 
Jerking is normal at speeds less than @ 8 mph. You can fix it by getting a larger rear sprocket. Of course you lose all of your top end. It's all a trade-off. Unless you want to install a jack shaft kit. That's a totally different animal though.
 
When I'm cruising around 8mph the bike jerks and I can hear the gears causing the jerks. My friend's bike does not do this, he's cruising same speed as me and runs very smooth no jerking. Could it be the adjustment of my clutch cable?
 
Cable adjustment will not cause transmission slop or "jerking".

Gearing, and quality internal parts on the transmission can though.
If you are running a Chinese in frame 2 stroke, I wish you the best of fortune on the quality part of the equation.

Have you tried lubricating the transmission gears with a high quality grease? That might help out a little......
 
I am running a Chinese 2 stroke in frame. The motor I have is the Flying Horse from Zoom "suppose" to be a good engine. It starts up on first attempt and runs very strong, stronger than my friend. This is the only issue I have with the engine, anything pass 8mph it's smooth and strong. I will try lubing the gears and see if that will help. Thanks guys for your input.
 
rohmell said:
No pull-start needed because it has a built-in sprag (one-way bearing).
You can still start the engine as usual by pedaling and dropping the clutch, after that, you can forget about using the clutch lever when slowing down and braking.
Click to expand...

That is awesome! Where can I get one and how much do they normally cost?
 
rohmell said:
No issues at all, I am 100% satisfied with the performance of the centrifugal clutch.
All my future builds will have one installed, I just picked up another three pieces for more builds.
Click to expand...

Did you buy it from BGF? If not where and how much did you pay for it? Did you have to make any modification to the clutch? I'm kinda leaning towards buying one. Thanks for your input.
 
rohmell said:
The first few I bought from ZoomCycles, but then they were constantly out of stock, so now I buy them from BGF.
On the first few installs, I would machine a keyway into the clutch so that it would mate with the Woodruff key on the crankshaft, but lately I have not had to do that, they go on and stay on using the taper-fit of the crankshaft, so right now, no modifications are being made to them.

Try one out and see how you like it. If it is no good for you, you can always sell it on eBay.
Click to expand...

So the ones from BGF now are all taper-fit? If so then I will order one, I would hate to have to do some modification. It sounds like you build alot of these bikes. Do you sell them?
 
rohmell said:
The centrifugal clutches have always been taper fit.
Some others members on this forum reported that their centrifugal clutch slipped and machined away the taper, so for the first few, I added the keyway to prevent this from happening.

I wanted to see if I could recreate the problems that some were having with slipping clutches and started to install then as is, but so far none of them have slipped.

There are some locals around here that have MBs, and they come to me for repairs and upgrades. I have convinced just about all of them to go with the centrifugal clutch, and those that have are very satisfied with them, and probably would not go back to manual clutching.

They are cheaper here:
Motorized BIKE GAS ENGINE parts - centrifugal clutches
Click to expand...

I just ordered one from the site you gave me, I hope it's an easy install and will not slip on me. Thank you so much for your help! cvlt1
 
rohmell said:
Good Luck with your centrifugal clutch.
Yes, it's a real easy install.
Let me know how it goes and how you like it after you have used it on your MB for a coupla miles.
Click to expand...

I'll definitely report back and let you know how it goes, thanks again for your help.
 
Rohmell,

I receive the clutch today but can't figure out how to install it. I took out the clutch cover and do I take out the small gear? Please help.
 
rohmell said:
Yes, the centrifugal clutch takes the place of the small gear.

Here are instructions:
http://www.zoombicycles.com/downloads/addons.pdf
Click to expand...

I checked out two instructions and one didn't say anything about cutting off the clutch studs while zoom instruct to do so. If I take off the clutch adjust screw, there's a spring in the back that will push the clutch out. How will I cut the studs without the clutch falling out? Also, my engine didn't come with a gear puller, can I take out the gear without one?
 
Thanks for the reply, I already have a Craftsman dremel tool that I can use to cut the studs if they hit the cover. Where can I get a gear puller? So basically take out the gear, install the new clutch and put the cover back on?
 
rohmell said:
Yeah, I have the Craftsman version also, works very well.

Engine sprocket and Clutch Hub puller tool here:
ENGINE_KIT_PARTS_PAGE_4
Maybe other vendors have it as well, this one is the first place I looked.

Yes, remove the gear, and the clutch goes in its place. The clutch does not use the Woodruff key, it relies on the taper-fit-friction to hold together.
Click to expand...

I was hoping to get one from a retail store somewhere instead of ordering one online. I don't want to wait a week just to get this installed. So insert the new clutch and tighten with the bolt that came with it? There's also 2 bolt that was in the package, what do I use those for?
 
I just ordered the gear puller, now I have to wait a few days to install the clutch this sucks! I was excited to install it when I got it yesterday.
 
Oh Yeah, I’m planning on tearing it up around my neighborhood with the old clutch when I get home tonight. I was just eager to install the new one, I hate the fact I can’t cruise at a slow speed without engine jerking. In the meantime I guess I can spray paint the covers black since my engine is black. Silver cover wouldn’t look good on a black engine. Thank you so much for your help and I’ll let you know how it goes when I get that part and have the clutch installed.
 
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