jerky accelleration

[AuburnRox]

Any help would be appreciated...

I put a 4.0 hp Subaru Robin on one of my minis. However, it shakes really bad under accelleration. It's not the engine, it's running really well. I'm thinking it's the chain tension? How tight/loose should it be? Could the clutch be going?

 

[Littledude56]

it is probably the clutch, the old clutch on my go kart did that, what I did (completely not recommended) is I greased the drum. I know how bad that sounds but what it did was make the engine rev really high before it started moving forward granted that engine is ungoverned I don't know what will happen if yours is and cant rev as high, but it did make is engage smooth as glass for a while.

 

[AndyT]

A chain should have some slack. If you grab it and raise and lower it, you should have no more than 1/2" of movement total. You can adjust it to between 1/4" and 3/8". It should never be totally tight. It's not likely that your chain tension would cause jerky acceleration.

How old is your clutch? Greasing it is BAD! :thumbdown:

 

[Littledude56]

I know greasing it is bad, just to let you know I am not recommending it I am just saying I did it and it smoothed out the accel on my go kart I realize that it is probably super bad for clutch life, but mine had almost seen it anyways so me and my friend were just screwing around. and believe it or not I don't think it slipped that bad at full throttle just from a dead stop start and even then it actually seemed to take off faster because the engine revved more into the power band before it locked up.

 

[AuburnRox]

I'll have to check, but I'm pretty sure my chain is too loose.....I may have as much as 1" total movement, not 1/2"......I'm going to raise the engine a tad, so hopefully, I won't have to remove any links in the chain.....

.....what do you think, could a very slack chain cause this issue???

 

[Strigoi]

I'll have to check, but I'm pretty sure my chain is too loose.....I may have as much as 1" total movement, not 1/2"......I'm going to raise the engine a tad, so hopefully, I won't have to remove any links in the chain.....

.....what do you think, could a very slack chain cause this issue???

i doubt it's the chain. the only way i could see it happening is if it's skipping teeth. also, your mount plate isn't slotted?

 

[AuburnRox]

I drilled the holes....no slots....I plan on putting a spacer in, maybe that will solve it......

 

[rudedog]

I would get a plate from cjtmini. That'll make sure it isn't the vibration problem, or you can figure out a way to reinforce your engine plate. I'd almost bet that's what's causing it.

 

[AuburnRox]

I put a sheet of rubber gasketing material between the engine and the mounting plate, then torqued it down very tight to ensure the nuts don't vibrate loose.....This raised the engine slightly and took up the excess chain slack....the "jerkiness" is better, but still nowhere near smooth....I guess it's the clutch?!

any other ideas?

 

[mini99]

take the clutch apart and shorten the spring a 1/2" or so. that'll loosen it up a little and smoth it out. or add some teeth to the rear gear.

 

[AuburnRox]

Question.....

I pulled the 4 hp off of a go-cart to put on the mini.....on the go-cart, the clutch was arranged so that the sprocket pointed away from the engine. However, this arrangement would not work when I put it on the mini. I had to switch the clutch around so that the sprocket faced the engine (in order to align the sprocket with the wheel). Could this be the reason for the jerky acceleration? Are clutches uni-directional?

 

[Strigoi]

the clutch can go on either way.