I have a trx350fe rancher that runs great for about 25-35 minutes. Once its warm and been warm for sometime the engine begins to sputter from idle to about 1/2 throttle. When throttle is applied the ATV occasionally bogs down and if throttle isn't released the ATV Stalls. When it doesn't bog it seems to be misfiring from idle to 1/2 throttle. I've cleaned the carburetor, adjusted the valves. The ATV idles fine and runs from 1/2 to full throttle fine. The issue only arises after about 30 minutes of use when the ATV has been warm for some time. I'm looking for suggestions on what to check next.

 

I have a 96' TRX300 and went through the same thing. On my carb, the fuel primer pump assembly was bad, sucking air into the carb and, at the same time, pushing bits of rubber up through the carb. Got a new one and the thing runs great. Hope this helps.

 

Did u ever figure out the problem? i have a 1985 honda fourtrax trx 250 utility that it idles good and it had a problem that if u put it full throttle it would bogg out and it sputtered really bad i adjusted the needle on the slide so the needle would plug more gas and the bogging went away but it still sputters really bad i talked to my neighbor and he suggested buying a carb rebuild kit so i might try that if u have any suggestions please reply! ty

 

Hey, I removed my carb and started to clean it. While taking it apart, I noticed the rubber boot around the primer was cracked. This allowed air (and some rubber) to suck in through the primer button = all of my problems! I ordered a replacement of the primer/boot assembly ($60) and my bike runs fine.
Good luck!

 

my 85 fourtrax 250 does not have a primer button but it has a rubber boot on the choke cable that is cracked would this cause the problem? or could i just take it off?

 

Not sure if the boot around the choke cable would be the cause of your problems or not. The primer button/boot mounted into the side of my carb. The boot was there to keep air from sucking into the carb. If any part is worn or cracked on your carb I would replace it. It wouldnt hurt to clean really good, too.

 

Hey countryboyg, I have an 87 Fourtrax 250. On the fuel shutoff valve there is a filter and an o-ring. Make sure the o-ring isn't falling apart I had this happen and pieces of the o-ring were in the carb. If filter is clean, o-ring intact, fuel flow to carb is good then clean the carb and see if that helps.