Hello I have a Honda Rancher trx400fa. After it gets warmed up real good it likes to idle high in neutral and won't allow me to switch from drive to reverse that easily. It also likes to give a nice loud backfire upon shutting down the motor. Does anyone know the sympotms and how to go about fixing it?

 

jd did you try to turn down the idle speed screw ? it's located on the right side of the carb the screw might not look like it goes to the carb because on some quads there is a cable attacted to the screw that goes to the carb ; this screw is big around enough to turn it with your thumb and index finger/clockwise to increase and counter clockwise to decrease idle speed !

A high idle speed can cause the engine to back fire however the choke may not be openning up completely causing a high idle speed also , the valves could also be off spec's causing the back fire ; the engine could be running to rich or to lean causing the back firing as well !

If turning the idle speed down doesn't stop the back fire check your spark plug condition/color of the electrode tip , a white grey color means to lean , black means to rich the color should be a tan/brown for the correct fuel air mix ratio ; if all these things checkout good try a new spark plug then check your valve clearance for the correct gap !

On my brother's 2004 Honda TRX350FM Rancher 4x4 the valve spec's are intake: 0.003" and exhaust is 0.004" , i hope this is of some help to you if not Hondamachanic will probally jump in with something else that could be causing your problem ; and welcome to the forums !..........

 

I just had the same issue. Turned out on mine, while moving stuff around setting the valves, I had pulled the choke out a little at the carb. make sure the cable is seated all the way at the carb.

 

The other possibility is an air leak somewhere between the carb and the head...

 

Thanks ya helped me out