My 1995 Polaris Trail Boss 250 (2x4) starts and runs fine for about 15 minutes, then shuts down as if it has an overheat thermal protection. After about 10 minutes it will start and run again for about 15 minutes. There is no cooling fan and no "Hot" light comes on. All fluid levels check okay.

Is there a thermal overload protector that would cause a protective shut down? If not, does anyone have advice that might remedy this problem?

Thanks, Jim

 

next time it does it check to see if theres any spark. also unscrew the gas cap to see if its under pressure.

 

I was riding in 97 degree weather at slow speed when the problem occurred and a fuel tank vacuum could be the problem. Spark appears strong. Today's weather was in upper 80s and there were no problems. Sometimes I overlook the obvious. Hope the solution is this simple....
Thanks for you input!
Jim

 

Well, I am disappointed to say the problem still exists. After riding for about 30 minutes the Trail Boss begins to make an erratic tapping sound, loses power and will not start until it cools down for about 10 minutes. When it restarts, you can ride for another 10 minutes and then it does another shutdown. Would a fan kit make any real difference, or is there a way to add a small oil cooler?.

 

Sounds like piston seizing and compression loss when hot. Check compresion, if low topend probably due. Hope rod,lower bearings ok. Also black pouch in front of battery has thermal fuse,check inside for corrosion on terminals. Hope its just electrical problem!

 

Thanks for your advice. Compression checked okay so hopefully no serious damage was done. I cleaned the thermal contacts and performed an injection test on the oil pump because the 2 cycle oil injector tank seemed to be holding its level. Additionally, the bike seemed to have quit producing the tale tale signs of 2 cycle smoke. It appears the injector pump is clogged or broken. I brought the fuel tank to a 40:1 mix and suddenly the quad is back to running like is should. I haven't determined whether to just disable the pump and stay with the 2 cycle mix, or to repair the pump because of the refueling convenience.....

Regards,
Jim