same thing i was thinking....lol i see what hes saying but the term "air leak" just doesnt fit well on some of those things...

 

I think we get what you guys are saying.
My engine on 1988 Polaris trail boss 250 when I start it right away starts with RPM screaming high, but when I open choke it idles OK and doesn't stop. I cleaned carb 4 times, ran wires through jets and small holes, checked that my floats working properly.
Now I need to check the adaptor that connects carburetor to the cylender for air leaks.

I will spray WD40 around it while running. Should my RPMs go down? What does WD40 do? Does it seal air leaks?

 

All WD40, carb cleaner spray,etc is to fill the void where the engine is sucking air and running wild and lean.It will slow the engine down a second or so. You can usually smell carb cleaner through the exhaust as it sucks it in. Could be a cracked intake manifold,base gasket,head gasket,engine case leaking or crank seals causing the problem. My bet is either the intake manifold or crank seals. Especially the one behind the drive clutch.Get this fixed before you do any piston damage.You can do a leak down test if it's not the intake manifold to help you narrow down the problem.

 

Thank you! I will defenetly try to perfom leak down test. In case the leak is at crank seals, do I need special equipment to replace them?

 

Just a cheap 5 buck seal puller is best to pull the old ones out. Put a bead of loctite around the outer part and set it in place. You can seat them flush with a round punch, a 3/8" ratchet extension etc. Just don't damage the new seal in doing so. Hardest part is getting to them. Clutches have to be removed along with the fly wheel and stator on the other side. Plus don't overlook jetting on the carb. From factory shows a 230 main jet,45 pilot.