I can only give it 1/4 throttle

I've got a problem with my 300ex. I can ride for twenty minutes or so and it will run perfect, but after a while something goes wrong. If I give it more than 1/4 throttle, than it starts making a popping noise and will not accelerate any further. Anybody got any ideas?

[Leo]

check to make sure the vent line that comes off the gas cap isn't plugged / kinked in any way...

Leo

[lil400exman]

all i can say is check your carb bowl or sum thin after the carb warms up gets clogged in a jet or sumthin i dunno know i had the problem with my dirtbike!

[jwisniew]

Same thing happens to me!

[yellow_ho_01]

CLEAN OUT YOUR BOWL,.. TAKE IT OFF AND CLEAN IT OUT,... ALSO WHILE IN THERE,... TAKE OUT YOUR MAIN JET AND SEE IF IT HAS A PIECE OF DIRT OR SOMETHING ELSE IN IT...

[Sportrax 400EX]

Have you done any new mods before this started or did it just start doing that one day? If it happened after a mod you might look at how your jetting it.

D.

[00400EX]

I SECOND THE VENT CAP THEORY. WHEN IT STARTS TO CUT OUT LOOSEN THE GAS CAP , IF IT CLEARS UP , YOU FOUND YOUR ANSWER. IF NOT CLEAN FUEL LINE, THE CARB.


HEY (Sportrax 400EX) ,WHERE IN VA ARE YOU , I'M IN MARSHALL / WARRENTON AREA?

BRIAN

Sounds to me like it could be an electrical component problem, maybe the CDI or coil. The reason I say that is because it is classic behavior of electrical parts going bad, works great till it gets warmed up and then it starts acting up. I'd check out the fuel system too though, especially all the vent hoses on the carb and gas cap. If you've made any mods to the motor recently, be sure everything is alright there too.

[Sportrax 400EX]

I'm in Alexandria but always ride in F-burg and Stafford area.

D.

[rookiex]

rings or carb

[big-guy]

is the choke still on?

[400EX22]

aight guys,
ive read what you've been telling will34, because on of my friends is haveing the same problem with his. and he has gone threw the carb, cleaned it completely out, checked the lines and all that, nothings dirty, kinked, out out of place, and we even took the gas cap completely off it when it was running, changed the plugs, drained and replaced the gas and oil, and checked all the air flow areas. and still it wont go past 1/4 throttle , anymore suggestions???????? or ideas??????

[HiperEX]

hey mine did the same thing today when i was riding i ride for about half hour or so then i put it in neutral with it running adn it would just shut off then i started it back up and only let me get it half throttle and pop and crapp like he said above then i just let it sit and looked over it to see if there was anothing restricting my air flow ect. then after awhile it just started up and just fine as it was is this like teh same thing you have wrong right with yers?

[bigb426ex]

Mine had the same problem. Died on me while on the last lap of a harescramble race. I had dirt clogged in the wires to my coil. Cleaned that up and it worked just fine.

[nathan2005]

Its prolly the main fuel jet in the carb.a piece of crud finally got washed in there after a while of riding and is restricting fuel flow after 1/4 throttle.it could also be debris or something getting between your breaker points.good luck, aka motorcycle repair technician :)

[R-Crazy]

check your fuel filter and your airbox/airboot. make sure you didnt leave the paper towel in the airboot. (ive done that). it could be electrical or even the rings. do one at a time and see where you go.

dave