300ex sputters after a wheelie or hill

[03trx300ex]

hello, i have a 03 300ex and everytime i pull a wheelie up or go up a hill my quad starts to die like it ran out of gas!!! i have pulled the carb off twice now cleaned it and still the same results!!! i have an fmf pipe and k&n filter as my only mods... has this happend to any one else and what did you do to fix it??? i mite have bad gas but it has done it even after i ran it out of gas and put new in... any help will be appreciated!!!

[GPracer2500]

First thing I'd check is that the float level is set to spec.

[03trx300ex]

thanx for your reply...anyways how do i do that exactly??? i read how to do it on a honda recon but two different quads...do you think the float is stuck maybe??? also how would i adjust it??

when you wheelie does gas leak from the carb? if it does it is probably ok. if you ever stood ur quad straight up and down while doing a wheelie the carb either empties itself or gets flooded. probably nothing really wrong with your quad

[03trx300ex]

not really sure if it leaks out!!! i no it does if i stand it up on the grab bar to work on it but dont no if it does during a wheelie!!! something is wrong because as soon as i get done with a wheelie it spudders and i have to play with the gas to keep it going...i have stood it up while it was running (not all the way of course) but i put it on two buckets that stood about two feet off the ground and it didnt do it... could i have water in my gas maybe??? just an idea!!!!

water in your air box maybe..... not sure

[03trx300ex]

nope checked that and dri as a bone

[Lightninn]

Break out your manual and check your float level...

If there were water in the airbox it would flow away from the engine during a wheelie. You would have to have alot of water in the box to cause that and I would think you would have noticed that if you've pulled the box lid and inspected it lately.

Now on the other hand you may have a little water in your float bowl on the carb.

I'm betting though if your quad runs perfect except during wheelies then your float level is off.

[03trx300ex]

i still dont no how to check my float level!!! can anyone help??? also how do i adjust it???

[GPracer2500]

Originally posted by 03trx300ex
i still dont no how to check my float level!!! can anyone help??? also how do i adjust it???

If no one replys, do your own research. I Googled "carburetor float level adjusting" and found several sites that should get you started. I don't know what the standard setting is for your carb. If your gonna ever be working on your bike you might as well get a service manual anyway.

[03trx300ex]

i was working on my problem tonight and i adjusted on two of the screws!!! one was on the side of the carb an one was on the bottom of the bowl!!! (it wasnt the idle screw) it isrunning better now and it doesnt wanna die when i come down from a wheelie now, but now it is doing the sluggish thing when i putt around!!! does anyone know what the screws are i was adjusting??? i would like to no so i can try and make my final adjustments!!! thanx everyone for your help!!!

[30ex-man]

yea this is happening to me to i thought that i could wheelie but then i was wheelie and it just turned off and wen u bring it back down it turns right back on.i dont know how to fix it but i ve cleaned the carb a bunch of times.i have the s.m. so ill cheak for the specs.

[03trx300ex]

mine would only die when i would bring my wheelie down!!! but anyways yeah check the s.m. cuz i bought mine used and i didnt get one... thanx...do u no what the screws are i was talkin bout

[30ex-man]

it says that the distance from the float chamber gasket surface to the top of the float should be 18.5mm or 47/64-inch.(this is being done with the carb hanging up right and if it out of spec to replace float and if still out of place to replace the float valve


tell me if u need anything else

[03trx300ex]

i will check that tommorow!!! thanx

can you tell me what the adjustment screw on the side of the carb is (not the idle screw) and the one on the bottom of the carb?? sorry if i am being repetitive!!! lol!!!

[300ex_#387]

Don't mess with the one on the side of your carb...thats the drain screw...always leave that one tight. The one on the bottom in your air screw...if your drain screw was loose that could be why it was cutting out...tighten it back up...

[03trx300ex]

thanx everyone that helped me on my question!!! i got it running...i found that i had a clogged overflow tube on the top side of the carb...i cleaned it out and havent had a problem since...wish i would have found that the first time i tore it down...once again thanx to all your help!!!!