I just picked up an almost new 2002 TRX90 that was barely used. It has a bad stumble and requires the choke to stay on way to long, even after the bike is warm. I replaced the plug and that helped some but it is still there. Above idle it runs very well. Could it be bad gas or could it be something else? As clean as the bike is I hate to open up the carb for no reason, and the gas doesn't smell bad.

 

First try to open the fuel air mixture screw a turn.

Sounds like the idle circuit is out of adjustment or plugged

If you want, you could remove the air cleaner, rev the engine and cap the carb end with the palm of your hand and let off the throttle. Repeat a few times. Sometimes this will clear the idle circuit of obstructions.

If it does not cure the issue, the correct way is to disassemble the carb and clean it. Make sure the fuel air screw has all components installed correct. Adjuster screw, spring slipped over it, then the washer washer, and next the o-ring. then insert inot the carb and adjust If the o-ring is missing it will idle like you described also

----- Gimpster -----

 

Thanks, will give it a try. It does only idle when hot not with the choke on cold start. I thought it should have a fast idle for warm up. Been out the game for along time.

 

My experience is that the slow (idle/pilot) jet on these carbs cloggs very readily. If it had sat all those years, no doubt fuel dried up in the carb and gummed up the jet.

Do a good carb cleaning, and pay particular attention to the slow jet. I just cleaned mine, and now it will start without the choke for the first time in years! These are great little machines!

 

It hasn't totally sat, the guy was pretty good and changed the oil every year and kept it running, just wasn't ridden much. He was an avid rider, just didn't have the grand kids much.