250 4X4 trail Boss -91

[Old Yellow]

Have a hard time starting & keeping it running.
When running it is pushing air out the breather
has any one had this problem
to me it almost seems like timing but not sure how to check it

[Outlaw]

My buddy has a similar bike to yours and we have to run it with the choke on to keep it going.I would start by taking the carb out and checking for restrictions in all the passageways,vent lines correctly routed,reeds?,air leaking in between carb flange(rubber boot/s).....my 2 cents worth...I've yet to look at it for him.....but that is where I'll start.

[Grizzly SE]

sounds like you intake valve isn't sealing or timing is out but I not a mechanic so I'm not positive. Sorry I couldn't be more help.

[muddyguy]

I had the same problem on my 91 350 trail boss,there was a pin hole in one of the rubber boots connected to the carb,once i fixed that it was good to go.

[Old Yellow]

Thanks guys I now have a few ideas to start with

[Xxploder400]

I'm thinking youhave a broken REED or something....pull the carb and boot and have a peek