Minibike lost 10mph

[Dk@t]

Get the rotary or comet belt. Also please post a picture from above of your driver and the driven ( also from the rear ) so we can see the alignment of the two clutches. On the 30 series, alignment has to be almost perfect. Misaligned clutches causes premature belt wear on an awful lot of karts and bikes. Kind of just like you are experiencing.

I don’t believe my cvt driven and driver have been misaligned but I haven’t checked them in a while

 

[Hellion]

I’ve hit 50 and had a fine time with this last belt from the same pack but maybe I’m having bad luck with this one….

What are you using to measure your speed? Just curious.

Its been proven over and over that the cheap belts just dont last. Some make it longer than others but all fail at some point.
The good belts will last. BUT, the cvt needs to be smooth and lube properly and aligned.

Ive never seen my belts get sticky goo. Thats the "rubber" breaking down.

When the belt slips or gets narrowed from missing material it will not fully engage the cvt. This leads to loss of power across the power band.

Compare the belts together. Im curious to see what they look like.
Can you get some more pics? Maybe turn on a light too, its hard to see.

This is a great one-post reply on the CVT, belts and issues thereof. Nicely done. That could be a “canned response”, something you could copy/paste ad infinitum.

 

[Dk@t]

What are you using to measure your speed? Just curious.



This is a great one-post reply on the CVT, belts and issues thereof. Nicely done. That could be a “canned response”, something you could copy/paste ad infinitum.

I have been using an app called “speedometer” and here are some of my test runs when attempting to diagnose the bike myself

 

[Dk@t]

I am happy to say that I found the problem, I bought a new chain, it came with a new 60 tooth sprocket and I thought “why not”. As I was getting ready to put on my new chain I find my rear sprocket is bent
And when I go to test after putting the new rear 60 tooth and chain I hit an astounding 48 first try! something I haven’t even been able to do for some time then I hit 50!!

 

[Whitetrashrocker]

Not a fair comparison for belt slippage when you just changed the gear ratio.

And I'm pretty sure a bent sprocket won't affect speed.

 

[Dk@t]

Not a fair comparison for belt slippage when you just changed the gear ratio.

And I'm pretty sure a bent sprocket won't affect speed.

I still plan to put the comet belt on but it was decently bent and the chain was old, I will do more tests to see if it’s consistent but this generally fixed it.

 

[panchothedog]

Your alignment looks pretty close. In your 3rd picture it looks like the driven is a little more out board than the driver. OMB Warehouse ( and probably others ) sell shim kits for this exact purpose. The shims are .020" thick. A common hardware store washer is about .050" thick. Yours looks less than .050 out. Getting them near perfect has its benefits. I've had belts last for 25 + hours of hard run time. Probably 300 miles or more. The shims are cheap, and the results can be well worth the effort.

 

[JimD]

How about a picture of the cover over the t/c?