High rev and backfiring

[ManofMosh]

thanks for the help in advance.

I have a 2001 300ex. After it warms up, it idles like a son of ***** and backfires when I shut it off.
I can't find any air leaks from the intake to the muffler. What's wrong????

[2004exrider]

Thats pretty wierd? Have you tried to just clean the carb, maybe that will help you out.

Jimmy

[alexmx22]

it may be back firing because of all of the extra fuel being dumped then turning off oyur machine, that last spark when you turn it off is prob lighting it all at once, try turning down your idle then turn it off and see if it still does it.

all quads back fire if u over rev em.

[bwamos]

Mine doesn't

It really does sound like you have an air leak somewhere. A high idle that you can't lower is a sure sign.

If you have a fresh exhaust crush gasket (1st place to look), and no leaks on the intake side, you may have a tear in your headgasket. It will blow air out on ignition, and suck excess air in on the intake cycle causing the high rev & backfire.

well i hear alot of quads back fire at high rpm. when i ride a wheelie i ride it till rev limiter and when i let of it back fires. and if im going fast and down shift it will back fire. i here alot of quads do that.

..bwamos...... i have a leaky head and cylinder gasket and all my oil lines leak on my quad. do u think thats y mine back fires? it also burns oil and has a fresh rebuild and valves ajusted. and the plug fouls out and is wet.

[Honda TRX250ex]

header leak?
running lean?

[bwamos]

Originally posted by blue450yo
well i hear alot of quads back fire at high rpm. when i ride a wheelie i ride it till rev limiter and when i let of it back fires. and if im going fast and down shift it will back fire. i here alot of quads do that.

..bwamos...... i have a leaky head and cylinder gasket and all my oil lines leak on my quad. do u think thats y mine back fires? it also burns oil and has a fresh rebuild and valves ajusted. and the plug fouls out and is wet.

From your other posts, I beleive the rebuild wasn't reinstalled correctly. Get fresh gaskets, rings, rehone, and reinstall the entire thing again following the service manual to a tee, or get a shop to help.

I honlestly think it was installed incorrectly. There's lots of tricks. For example on the head you have to tighten the bolts down in a cross pattern about 1/4 of the way at a time, or you will warp your head, etc.

Nothing against you bro, we've all had bad installs before Live and learn.

Originally posted by bwamos
From your other posts, I beleive the rebuild wasn't reinstalled correctly. Get fresh gaskets, rings, rehone, and reinstall the entire thing again following the service manual to a tee, or get a shop to help.

I honlestly think it was installed incorrectly. There's lots of tricks. For example on the head you have to tighten the bolts down in a cross pattern about 1/4 of the way at a time, or you will warp your head, etc.

Nothing against you bro, we've all had bad installs before Live and learn.

the shop put it in.

[CDCHONDAS]

Granted you have some problems with your motor but if it runs fine throughout the rest of the powerband I would try adjusting the air screw located on the bottom of your carburetor