ATV project

[LAWN BOY]

Working on my 90s Polaris 250 2wd 2 stroke ATV. Used spray carb cleaner to clean the carb today. Throttle response is now good. Idles a bit low. The shifter doesn’t like to go all the way into low or reverse, and when it did, I drove 6 inches before it stopped and squealed like a pig. Google says the belt is probably bad, but idk, here’s pics. Also where exactly should I spray what to test for an engine air leak? This is the first ATV I’ve worked on this much so this is out of my knowledge base. Any help would be greatly appreciated. Thanks for your time.
BTW: clutch cover has 2 tiny cracks and doesn’t seal perfect as you’ll see in one of these pics. And a tube going from clutch cover doesn’t line up perfect with that other tube…

 

[Yukon Stihl]

Pressure and Vacuum test same as a chainsaw.
You will have to strip it down to get to the seals if it doesn’t pass the tests

 

[GMB74]

Remove the belt and check it for a worn spot. Someone probably got the machine stuck and horsed it trying to get it out, burning a bad spot in the belt. If so, need a new belt.
The clutch covers do not have to fit perfectly for the machine to work, but do need to fit to keep water and dirt off the belt and clutches when running off road. The plastic covers are known for warping with age like the ones in your pictures. Replace them if they are still available or figure out a way to cobb them up to seal the best way you can.

As Yukon Stihl says, fabricate some block-off plates and P/V test just like a chain saw.

 

[Loony661]

If you want to test with carb spray, you need to let it idle, and then give short blasts along the cylinder base, as well as along the crank seals. If there’s a change in RPM when you spray (or very shortly after) you’ve likely found an air leak. Another place that likes to fail, is the carb boot. They dry rot and start sucking air after the carb, leaning the mixture out.

 

[fossil]

You need to find the minimum width spec on the belt to see if it's worn too small.