300ex braking up

[Honda TRX250ex]

i just rebuild my 250x i put piston rings rockers cam and intake valves in it. but when i went to start it up it broke up very bad
i tryed adjusting the carb to home specs and the timeing is right
me and my dad think that the float bowl is is over flowing and not enough air is mixing with the gas and a tube that comes off the carb is leaking gas
could that be the problem or could it be something else

[300ex73]

Idk if you've found the problem or not yet. But, there should be gas coming out of any hose connected to the carb. Here's something you should check if you're getting gas out of a vent hose. There's a flat blade style screw located on the left side of the carb, near the bottom on the float bowl. Make absolutely sure that you have that screw tightened down completely. That's the only reason I can think of that it would be leaking any gas from a hose.

Also, when you say it was breaking up pretty bad, I'm assuming that you meant it was running really rough. Idk what you've done to the motor, or what your elevation is. But on my 300 which is internally stock, I'm running a 42 pilot jet, airscrew out about 4 turns, 138 main jet, and moved the needle clip down one position(we're at 915 ft above sea level). The jets are replacement Keihin pieces, and the needle is stock. I tried using the Dynojet kit, but wasn't very pleased with it.

The only thing that has been done other than the filter, pipe, and removing the lid is that I removed the choke from the carb. I don't need it anymore, not even when it's cold out. With the larger pilot jet it fires the first time about 95 percent of the time.

Anyways, it's a lot of prolly useless info, but hopefully you can get some kind of help from it. Hope you get it runnin soon.

[Honda TRX250ex]

i went over the whole carb did all the adjustments and thats not the problem everythings working fine on it...
could it be somthing else like the timeing is off
i also have a 300ex OEM cam on it could that be the problem?

[300ex73]

I don't really see the cam being the problem, although it's possible if it wasn't set correctly. And I have doubts that it's the timing. What exactly is it doing? Give me the best description you can of what's happening when you rev it.

[Honda TRX250ex]

ok it idles fine but when you give it some gas it spits and spudders like crazy and kinda bogs out
like somtimes when its sitting in nutral and i give it some gas it dont brake up but when i put it in first it brakes up badly than when i go to put it back in nutral it brakes up

[bwamos]

Originally posted by Honda TRX250ex
me and my dad think that the float bowl is is over flowing and not enough air is mixing with the gas and a tube that comes off the carb is leaking gas could that be the problem or could it be something else

1) Lightly smack the float bowl with the plastic end of the screwdriver handle a few times. Sometime the float will stick when you clean it.

2) If that doesnt stop the leak.. you need to adjust the float level back to factory spec.

3) If that still doesnt fix it.. you need to make sure that the check valve is working properly and or the check valve seat isn't worn out or damaged. You may need a new check valve.

1 of those 3 should stop the overfill and potentially fix the other issues.


Regarding the cam. I'd imagine the 300ex and the cam 250x cams are slightly different. Nothing that would cause any huge problems. 300 probbaly would have a slightly longer duration or lift since it's a slightly stroked version. But, they may be the same since the 300 is corked anyway.

[bwamos]

Oh.. and you need to let her warm up.

They will always sputter and die when cold if you blip the throttle.

[Honda TRX250ex]

we fixed the float problem and yeah we let her warm up
we just cant figure out whats wrong :(

[300ex_#387]

im pretty sure mine had the same problem as yours, when you give it gas does it just die? If so then you either got some water or sand in your tank or you got water or sand or dirt in your air box or carb., just clean out your carb and airbox real good and dran all the gas and get the tank cleaned out real good and it should do just fine. Same exact thing happened to me

[ZeroLogic]

hey im his brother

300ex_#387 the carb, gas tank, air box/filter are already cleaned well and the gas is fine it was the same that came out of my 300ex and no problems with it how 300ex rides

[300ex_#387]

ohh well then i have no clue...take it to a shop and just have them look it over instead of actually working on it and get an outragous bill, or if you know a local repair shop and got some connections have them look it over my neighbor has a shop and he does it for me.