I just finished rebuilding my sons Honda TRX 90 atv. At first it started great and idled fine. We did the break in process as the book said. It started fine and seemed to have a whole lot more power for no more throttle than we were able to give it. After my son rode it for about 30 minutes I noticed that he hadn't taken the choke off yet, I turned the choke off and from there couldn't get it to idle correctly again. I tried playing with the choke and the idle adjustment screw. I didn't jack with the pilot screw cause to my knowledge it has never been messed with. I think the carb needs to be taken off and cleaned throughly. It just doesn't seem to respond at all to adjustments. The motor sounds and runs great at 1/4 throttle. I was wandering if anyone could tell me what to look for when I disassemble the carb? Just like clogged passages or what? I've never really worked on a carb before other than changing the main jets and didn't know how difficult it would be. Any suggestions would be appreciated.
Thanks DennisC

 

The way it sounds, your idle curcuit is just plugged. take the carb apart, spray carb cleaner through all the passages, then blow them dry with compressed airOnce you put it back on, then just readjust your idle screw.

 

When removing the air fuel mixture screw durung disassembly, make sure the spring, washer and o-ring are removed before blowing the passage out with carb cleaner and or air. sounds like the slow speed jet is restricted, or the spark plug is fouled. Like I say when reinstalling the fuel air mix screw, The o-ring goes in the carb first, washer next, spring then adjuster screw. If the o-ring is missing or installed on the wrong side of the washer, drivability and start problems can be noticed.

----- Gregg -----

 

did you do any mods to the engine? Did you bore it at all? If so, you might have to re jet it anyway. But clean it first, re-jetting is a pain to mess with, especially if your problem is a clogged passage or something.

 

Thanks for all the info, lets keep it coming. I had it bored out ten thousandths. It could need rejetted but I doubt it cause it ran fine at the beginning. I never thought about it but the spark plug could be fouled from the extra oil I used in the assembly process. Thanks Dennisc

 

Look over the pilot jet real good. The hole thru it is very tiny, and if its plugged youll get those symptoms. Pull the jet out, and try looking thru it like looking thru a straw...if you dont see light come thru...its plugged. If you cant get the hole cleared, just go buy a new one, they arent expensive.