I recently purchased a 1987 Warrior 350 and it runs great but if it is warm and I let it set idiling for a minute it quits. Once I pull the choke out it starts and if I keep it above idle it runs fine. The previous owner installed a new FMF pipe and I can only assume that he did not rejet the carb and it could cause it to stall out. The number on the small jet is 42.5 and the larger one next to it is either 155 or 755. Are these the stock sizes?

 

look at the main jet. should be a 145. with just a pipe, you really shouldn't have to re-jet it. I bought mine with a cobra pipe and stock jet and it was running rich. what does your plug look like? if its old, I'd change it out and go from there. do a full throttle run up until 4th gear and shut it off and then check the plug.

 

I reassembled everything and set the air mix screw at 2- 2 1/4 turns out and it seems to be running great. This morning I had the front cover off so maybe something had grounded out???