400 ex Back fire and leaking gas... Advice plz

[Shane_Tweezy]

New to the forum. Hope this question isn't one of those "millionth time" posts..

I finally got my stock 2002 400 ex running today (again). Over the past year, I've had alot of trouble with getting it to run RIGHT. It all started when I left it sitting up a few months (during winter) and didn't drain the tank. Obviously, the gas gummed up the carb. Once I took the carb down and cleaned it out as well as I could, it ran again. However, it was backfiring when I let off the throttle, and fowling spark plugs like crazy. It would also just randomly decide to die while I was riding it, and REFUSE to start back up... I would have to just let the bike sit a while.. Then it would start again.. Run a while, then die.... I took the carb apart again to make sure the float wasn't sticking, cleaned it again, and reassembled it. Same problem..Run for a few minutees, and die.. I left it alone for several months after that..
Today I decided to give it another go... I sucked all the gas out of the tank with a (gas stealing thingie) lol, and there was some trash in the gas..So I flushed it a few times with clean gas..
To the point... I got the bike started, and rode it for a good while without it dying! However, it's still backfiring when I let off the throttle to decellerate. The idle changes when I let it sit there running.. It will rev high, then low, and sometimes die, but start back up with no problem...It also leaks gas from the (over flow) ? line too.. it will just start leaking and stop randomly.. I read somewheres on here that leaking gas is almost definately the float. I'll try to adjust that tommorow to see if that fixes the problem... What about the back firing though? And the random idling?
I'd appreciate some pointers.. thanks!:confused:

[Shane_Tweezy]

Oh, and one more quick question... I'm not sure if this is normal or not..
A few minutes after getting it started for the first time and allowing it to warm up, I noticed that the headers were glowing bright orange...It was getting dark outside, so I'm not sure if it alway does this, and ive just never noticed it in daylight, or if this is something that has never happened before.. When I say glowing orange, I mean these damn things were obviously EXTREMELY HOT!! Like a stove burner on HI. Doesn't seem like they should get that hot....Normal or NOT?

Edit: Just did a search and found that this is very common. I'll leave this here though since it may have something to do with my backfiring/idling/leaking gas problem...

[honduh440]

im assuming that if ur pipe is glowing then u have a brand new pipe "glowing is ok" and you didnt rejet the carburator which is why its running like crap and dieing

[mojoe2878]

take the carb back off and clean it up real good again, take the jets out and the float off and clean everything. used compressed air to blow out the jets and all the small circuits and holes in the carb. if you put an aftermarket exhaust on there or anything then you need to go up on the jetting some. the backfiring may be your air/fuel screw being set wrong. after you clean it up tighten the air/fuel screw all thw way until it just lightly seats, the back it out about 2 --2 1/2 turn and try it then. you may need to fine tune it a little.
the leaking gas sometimes sounds like the float pin may be gummed up still and not letting the float move up and down freely all the time. the float needle tip may also be dirty and not letting it seal off when the carb gets full of gas.
if you put on a new header or took the stock one off for any reason then besure its not leaking at the head, you should have put in new exhaust seals if you removed it. if its leaking there then it will suck air into the head and also be a cause for it to back fire when you let off the throttle.

[chucked]

backfiring usually = lean
glowing red pipe = lean

[zephead400ex]

Take the carb off again and clean it very well! Make sure the float is functioning correctly. It sounds like there may be more than 1 problem; the carb is still "gummed" up from the old gas and possibly the float is not functioning correctly and possibly incorrectly jetted.

Like Chuck said, if it backfires on decel, then you are probably jetted lean. What jets do you have in right now? Are they stock? 38 pilot and 148 main. If you are still running stock jets, try a 42 pilot and a 152 main.

[racer94]

ok i am gonna hit a few points here,cause really there are many symptoms of a backfire,the first one being to lean of course,second alot of times an engine will backfire when you get off the gas because when you let out it shoots an extra amount of gas into the cylinder and when it is ignited it will backfire...when you explain the pipe glowing red,sometimes that can lead to a bent valve which intern would also backfire...i would start with the easy stuff and if that doesnt fix it look more into the more severe stages...start with jetting,check the carb again,as well as spark..then go from there...good luck!

[Shane_Tweezy]

It's not a new pipe. It's stock, and the original that came on it.

Like I said, everything is stock.

So if i'm not mistaking, the fuel/air screw probably needs adjusting to fix the running too lean problem?

What does "rejet the carburator" mean?

[racer94]

well i have never had a problem with the pipe glowing,but bent valves will cause it to do that,but so will being too lean so you need to go through the process of eliminations first....what we mean by rejet the carb is buy you some different size jets(bigger) and put them in,this will put more fuel to the motor makin it richer and less lean..you can also raise the needles as well...

[chucked]

Originally posted by Shane_Tweezy
It's not a new pipe. It's stock, and the original that came on it.

Like I said, everything is stock.

So if i'm not mistaking, the fuel/air screw probably needs adjusting to fix the running too lean problem?

What does "rejet the carburator" mean?

Have you modified anythign with the intake/exhaust system. Took the baffle out, Put in a different air filter, removed the air box lid???
Have you touched anything on the carburator?

If not, you probably just have some gum on a jet somewhere.

[bradrenea]

There is probably just still some junk in one of the fuel circuits. If one of the circuits is partially clogged it will cause a lean condition. I would pull the carb completely apart and clean it thoroughly. I'd bet money that would fix the problem if it ran fine when it was parked and no aftermarket parts have been added since.
I have one of the buckets of carb cleaner that I usually soak all metal parts in overnight, and then blow all circuits out with aerosol carb and choke cleaner. It always works well. If you try it, make sure to remove all o-rings, accelerator pump, and other rubber parts because the cleaner will turn them to mush.