250X with 300EX

[KeHall]

I have a 87 250X with a 300ex jug and head and im having trouble getting it to run i have used every time mark on it it will idol but as soon as u touch the gas it dies i have tried every thing i can think of any help would be greatly app

[underpowered]

sounds like fuel issues to me. tried cleaning the carb?

[KeHall]

yes i took the carb apart a cleaned it

[400eXr1d3rZ]

Change the sparkplug.

[KeHall]

It Has A new Plug

[Kickstarts-suck]

I don't think it would be timing if it will run.

Whats your jetting? mods? plug color?

also have the adjusted the valves since you got the top end on it?

[wilkin250r]

Honestly, it sounds like a carburetor issue to me.

Imagine if I said to you "I have a quad that runs just fine in neutral, but as soon as it's in gear, the wheels fall off. Do you think my valves are adjusted right?" That just wouldn't make sense, right? The valves aren't going to make the wheels fall off.

If your quad idles, then it's a pretty good be your engine is good. That means it must be a FUEL problem that is causing your engine to die. Poor jetting, air leak, clog in the airway, ect ect.

[KeHall]

we jetted the carb down 1 size I cant rember the size

[KeHall]

The valves were adj after the head was put back on

[bwamos]

Sounds like you need to raise the needle up (clip down). The needle on the 300ex/250x carb is either good or bad.. it really doesn't have much gray area. 1 position will go from falling on it's face to running great.

[KeHall]

Does it hurt that the air box aint on yet i was tring to get it right before putting the rest of the quad together it does seem like it is dumpnig the fuel in to the motor

[wilkin250r]

Bwamos might have nailed it on the head. I had a similar problem with a 250X, it would idle great, but it would die as soon as you hit the gas.

Turns out, the clip was top position, needle all the way down (leanest position). As soon as you hit the gas and got off the pilot jet, it was starved for fuel and it would die. A quick change of the clip position fixed the problem.

[wilkin250r]

Originally posted by KeHall
Does it hurt that the air box aint on yet i was tring to get it right before putting the rest of the quad together it does seem like it is dumpnig the fuel in to the motor

Yes and no. If the problem is the needle like Bwamos suggested, it would only make it worse. Also, if you let it run for a while, your mixture could be lean and overheat, or inadvertently suck debris into the engine.

But for ten seconds at a time, it's not a problem, as long as nothing gets sucked in.