QuestionI don't have a Honda motor cycle, but i have a Honda Trx 90 1997, It was bogging down when i pushed the throttle, so i took the carb apart and cleaned it and the jets. My mistake was i did not remember how much the fuel screw and throttle screw were screwed in. I put the carb back on the four wheeler, and started it, the machine idles nice, but when put in gear and the throttle pushed it dose not have enough power to move the machine. I don't know if the engine is not getting enough gas or if it is the clutch that is going bad. Why does the machine idle good, but not have enough power to move the wheels, unless its in the air?
AnswerAdam, I don't know much about a TRX90, but in general when the bikes idle well and don't make power on demand, the causes are often due to the jet needle setting or restricted main jet. I don't know if you removed the main jet holder and cleaned out the cross-drilled holes, but they are important, as are the air bleed inlets in the carburetor throat. The bike has CDI ignition which is usually pass-fail, but you need to check to see if the spark advance is functioning, using a timing light.
Looks like the carburetor has a #80 main jet stock. IF you have changed the intake or exhaust system, the bike may be running lean and you have to go up on the main jet sizes a step or two.
Something often overlooked is the valve clearances on these small motors. The clearance is only .002" but needs to be there or the engine will run poorly and have low compression.
The air mixture screw can usually be backed out about 1.5 to 2.5 turns. The idle mixture screw only affects the idle mixture and to a small degree the transition from idle to part throttle. The idle speed screw is just to raise the slide up and down to adjust the engine's idle rpms.
Make sure your air cleaner is clean and there is no damage to the exhaust system that could cause excessive back pressure.
Bill Silver
