Why My Cart is Slow (I think)

[Chilly]

Engine seems to run fine. I think it's the clutch and maybe belt. Help test my thinking:

A stretched belt can only get so high on the primary sheave before losing tension and slipping. Figure mine is neglected and stretched, based on apparent lack of maintenance elsewhere on the machine (golf course fleet).

Primary clutch rollers are flat-spotted clear through to the sleeve. As weights swing out against rollers they draw the sheave halves together, increasing effective diameter of the primary, increasing speed. With flattened rollers (and maybe worn weights) the same amount of weight swing will not draw in the movable sheave as far so unable to get into highest speed ratio.

Are the sheaves supposed to be a continuous smooth angle? Mine have some waves.

[Dave in VA]

Need pics. If the sheave halves are dished/worn, it may not be rebuildable.

[Chilly]

Not a great photo. Able to tell how worn?

[Chilly]

Bad photo. I'll be pullin the engine to thoroughly clean under the tin work. I'll scuff the glaze off of them then take a better photo.

[Chilly]

Ok, sun is out. It's a balmy 40-deg. So I pulled the belt, wrapped tape around the bottom of the valley between sheaves to keep debris out, then scuffed the glaze off the sheaves. I also marked a radial line with a Sharpy so I could see how high my belt is getting. Here are the photos. Should I expect the belt to get higher on the sheave than this?

I think it did go a little quicker after scuffing.

[Chilly]

And here are better photos showing the profiles of the inner and outer sheaves.

[Lochlin]

On the side where you marked with a sharpie (great idea by the way) that belt looks like it can probably be getting a little bit higher but not too too much. To be honest, it looking at the wear pattern on the side you didn't mark, that side looks too low. There might be an optical illusion in play.

On the side you didn't mark with the sharpie, does the wear pattern indicate where the belt is stopping on the clutch? If so then that's too low for sure.

Your sheaths have some pretty good wear on them as well. Those should be smooth whereas yours are ridged. It could be that your belt is staying within a ridge.


You may want to try a fresh belt before you go crazy with the clutch. Those belts wear like you say. Worse, it's not unusual to have a supplier to sell you the wrong one. Even a little bit longer or shorter will affect performance. Too short = jerky starts. Too long = poor top end speed.

[Chilly]

The moving side (unmarked) taper does seem to flatten out so the belt likely encounters a vertical wall on that side. The other side still has a taper to climb and may force the belt higher despite the moving side no longer assisting.

But the rollers are severely flat-spotted so I'm thinking the weights may reach their travel limit without sucking in the movable side far enough to reach top ratio.

I know the "right" remedy. This droid has a bad motivator.

[expo]

I’m curious what your top speed is? Do you have a portable gps or speed app on your phone?

[sho305]

It wont work well if your rollers are bad, period. They last a long time but if they are not rolling with no flat spots they don't work right. If your sheaves are worn in that is bad, but it will still work until they wear through and tear up the belt or break off. They wont shift quite right, they might not shift all the way. What you can do is get a wider belt like a 1.25 or the kevlar HD belt from cpp is. That will help some. A really worn belt will not work well, it will work even worse on a lifted cart that is more sensitive to wear. Yamaha says 1" on a stock cart but that is pushing it, and on a lifted its way bad, and if the sheaves are worn add that to it. But you need to fix or replace the the clutch rollers before you bother with anything else. A cart engine does not make enough power to slip this belt, it would be the clutch not working properly which means its really messed up. This size belt will hold 100hp. Or your secondary has problems too as it manages the tension. Usually wear on the sheaves is worse if the cart is run in sand. When the CVT has a problem you are not getting your limited power to the ground, it affects your performance more than you think.