I have 2002 Polaris scrambler 400 runs for about 20 mins. then dies will start right back up and do the same thing.rebuilt carb new fuel valve took exhaust off when I had the carb off and the exhaust off I turned it over and I get pressure back out of the intake any ideas.this is a two stroke.

 

Two things I can think of first to check. One is make sure the tank vent and carb atmospheric vent tubes are clear and open,not kinked. The other is to do a compression check. This can tell you what shape the top end is in. Sounds like either she's getting warm and possibly loosing compression or air may be restricted from the tank or carb and it vapor locks. Then let it sit a minute,it gets another glug of air and can run for a little while more until the same thing happens again. By the way welcome to the forum..

 

thanks ill check the compression. also one other symptom runs great up to half throttle then just flattens right out.i ran it with the gas cap loose same thing tho nothing past half throttle and still dies. just curious were these motors prone to this type of issue

 

If you removed the gas cap,then that eliminates a vent/lack of air problem.Plus if it's getting fuel,no restrictions, then that's why I'd do a compression check next and see what it shows. If it shows close to a 100 psi or less,that could be the problem. Could be getting warm and rings could be loosing grip on the cylinder walls. Again it's just a guess until you check it out.

 

Welcome