Got this 2005 Hond 400Ex in the shop. (auto shop other tech owns bike but we are both stumped) Here's the prob:

Wont idle correctly = unstable pops out of carb and then dies. first check for air leaks using propane. found air leak at carb tube to engine (bad o-ring) fixed and still have sam prob but no leaks shown with propane.

Tore down carb and clean totaly. just shy of dipping the carb. reassembled and same prob.

no motor response when trying to adjust air bleed either all in or all out. Seem to be running lean? PLEASE HELP~DESERT RIP LESS THAN 3 DAYS AWAY [img]i/expressions/face-icon-small-smile.gif[/img]

 

Jets in it are 38 and 148 was told it is stock and never worked on / serviced since it was bought.

 

your pilot jet is too lean! if its popping out the carb at idol then your pilot is too lean. locate your pilot jet; outside the bowl, side closest to the motor. skrew it out 1/4 turn at a time until it no longer pops.

that works provided you have no air leaks. propane is dangerous, there are other ways to check for an air leak. iwould say check it agean this way. take off air filter, place hand tightly over intake. hit the kill switch then run the electric start for a few turns. this will create a vaccume in the intake. if there is no leak the vaccume will last for a good 30+ seconds. if you do have a leak the vaccume will only last a few seconds.

hope this solves your problem

 

Update: Upgraded both jets main and pilot 2 sizes. Same problem. No response when turning pilot tuning screw (air fuel).

Turn off fuel run carb carb plug vent hose; fuel overfull hose and crank engine. It holds vac with hand over carb.

Any Ideas??? Still running lean. Do I have a bad carb? What else will cause this to spit out of carb and kill motor?

HEEEELLLLLPPPPPP!!!!!!!!!

 

i just bored my ex a few weeks ago , 2 the shop they said i was runnin lean & i went to a 42 instead of a 38 , i didnt change the other one , what will that do (shop didnt say anything bout the bigger one)im startin to loose confidence n them

 

are you sure your timeing and valves are correct? if the valves are out of alignment that might cause a carb backfire