Shift kit engine jerking

[MonkeySeller808]

Hi everyone,
I have a SBP shift kit and been having this weird problem. When I ride I do not clutch shift and only use te clutch when stopping. But when I am in a medium gear like 3~5 and ride full throttle, my bike seems to like have small little jerks. My chain is shifting correctly now, so the chain is not slipping or anything.
I tired adjusting the clutch to make sure yet it is not slipping. I can't think of any other problems.
Anyone experienced the same?

 

[young grease monkey]

check if any of the many chains are loose. it could be it is trying to jump off but doesn't have enough slack, so it gets yanked back on.

 

[timboellner]

Here are 2 things I would try from my experience with the shift kit:

1) Make sure that you don't have any stiff links in your peddle chain.
( This is the one that goes to the rear derailer and rear freewheel)

It only takes 1 link to be stiff and the chain won't run smoothly through the rear derailer idler wheels.

Start at the master link if you have one and go all the way around link by link and bend each one by hand making sure it flexes as it joins the next link. Lube the chain or learn how to use a chain breaking tool to loosen the stiff link a little bit if you find one.

2)Make sure your shifter is sequenced correctly.
With the engine off and clutch lever pulled in ride the bike around shifting gears and make sure if the shifter says that it's in 3rd gear that you're actually on the 3rd sprocket. It shouldn't make that noise like its between gears, or be jumping back and forth to the next adjacent gear. It needs to stay and hold in the gear it's supposed to be in each and every time you shift up and down to the next gears. Try shifting in and out of each gear a bunch of times to make sure it's right while the engine is off.

If your chain and rear freewheel/freehub are old and worn replace them.
Sometimes the chain can start to jump teeth if either the chain or rear freewheel teeth are worn. Also look for worn or bent teeth on the sprocket teeth both front and rear.

There's a lot going on at the rear derailer. It can't be bent or twisted.
(like if the bike hit a curb)
Once it's bent it never adjusts correctly and will drive you nuts.

The spring loaded mechanism that keeps the chain tight needs to be lubed and tension adjusted properly so that the idler pulleys are close to, but never touching the rear sprockets. Lube everywhere that pivots on the derailer.

It's also possible your rear freewheel has a bad pawl inside and under load is
skipping. Try peddling up a steep incline and see how it does.

Check all this stuff, especially for a stiff link in the chain .

TiM

 

[MonkeySeller808]

Thanks you for your replies. I am going to try test all these again on the morning. This problem is really scratching my head... I don't like the feeling when your riding and something happens and then you need to ride in fear.....

 

[reclaimer]

I get some thing like that. full throttle, rpms kinda surge slightly, bike lurches to the right, more of a wiggle really. Tracked it down to a front motor mount working itself lose.(gt lts, sbp kit, 49cc ht)

edit: Also the problem seemed to be worse with a cheap bell chain. Replaced with an old kmc laying around my garage, seemed to lessen how often it happened. So much so that I thought the chain was the problem, til it came back.

 

[MonkeySeller808]

I get some thing like that. full throttle, rpms kinda surge slightly, bike lurches to the right, more of a wiggle really. Tracked it down to a front motor mount working itself lose.(gt lts, sbp kit, 49cc ht)

edit: Also the problem seemed to be worse with a cheap bell chain. Replaced with an old kmc laying around my garage, seemed to lessen how often it happened. So much so that I thought the chain was the problem, til it came back.

That was the problem! How could i have overlooked it.... After riding a bit this problem went away, then this rattle started to happen during 1/2 throttle. Then this morning I saw your reply and I check the nut and it was loose. Tighten that/ red lock tight this time... Then the rattle stopped and no more jerks. This could have lead to more failures overtime. Thanks

 

[rustycase]

i got SO MANY deraileurs!!!!!!!

anybody wants one, I'll mail it to 'em for the cost of shipping...

tell me what kind u want and I'll look to see if I got that one.

Best
rc