400ex wont idle and backfires??????

[rappin_ernie]

I can't seem to figure out my 400ex. It starts right up and has a lot of power, however, it wont idle, and it backfires out of the exhaust and carb.

I put a new plug in, adjusted the valves, checked the timing, cleaned the carb and the problem persists. I can't figure it out.

The only things I can think of is that it's not properly jetted (Big Gub Slip on), or it has bad gas.

Any ideas??

Thanks!

[honda400ex2003]

whats the jetting at now? steve

[rappin_ernie]

I believe it's stock. It's only a slip on though, and stock filter. Do you think it could be the fuel screw?

[440ex. ehhh!!]

you still have to re-jet for a slip on. X2

but don't ask me what to go to, i haven't a clue about jetting. ;p

[rappin_ernie]

neither do I lol, but I would think the bike would still run half decent or at least idle. Somethin tells me theres a problem somewhere else.

[honda400ex2003]

150 main, leave the needle, 38 pilot, 3.5 turns out on the f/a screw should get you where you need to be. check for leaks around everything too. steve

[rappin_ernie]

Well, I'm not quite sure what exactly fixed it, but I got it running nice and smooth. I drained the gas from the tank and bowl, still ran funky, played with the fuel screw, couldn't get it right, and then finally I noticed the plug wasn't all the way screwed in, it was tight, but I got it to turn about ten more times lol. I think the threads are messed up, but now it runs very good. Thanks for all the help!!

[TRXRacer1]

Got any good pics of your quad? I just want to make sure that neither my buddies or I ever end up buying it some day....... Haha!