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engine shut off when idling - crf450x 2009

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hy guys.

i am new to this forum and i start here my first thread with an problem on my crf450x 2009.

also sorry for my bad english. i am from austria and live in the dominican republic.

i bought this bike new in the box and never had a single problem with it.

now i have a bit more then 10.500 kilometers and about 190 houers on the engine.

valve clearance is perfect!!!

my problem now is that when i stop on a traffic light the bike idle great and then a moment later the engine shut off. i can start it again in like 2-3 seconds later but sometimes it happens again. just when the engine is idling. the power is perfect and when i drive nothing happens. just when i stop or pull the clutch she shut off without any sign.

it makes me crazy because its happens on the worst places and moments.

i had a switch on the bike to kill the ignition so nobody can jump on the bike and drive away. i disconected it already but the problem still there.

if anyone knows this problem, please let me know.

greets from the dominican republic,


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Not sure if you have a tachometer, but are you sure your idle is correct? Should be about 1800 RPM, but yeah, it's probably your pilot circuit

I also had an issue the other day where my hot start got stuck. Bike would stall if I turned my bars all the way to the right.

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hy guys.

thanks a lot for all youre answers.

i forgot to tell you that the carburator cleaning job was my first priority.

it was very clean after 5.000km from my last cleaning job.

i was thinking the same about the pilot jet but no, they was nice and clean.

but hey. it cant be a carburator problem like a wrong jetting or a wrong adjustment, because i drive this bike now for more then 10.000 kilometers without any problem and without any change to engine or carburator.

they only thing it was happened that i had a hard crash on the road with 80 km/h and there i think the bike become maybe a little punch to the electronic, but it was 3.000 kilometers before the now existing problem.

what do you think about the cdi???

or whats with the sensor on the carburator??

can this sensor make such a problem???

and thank to advise me about the idling speed at like 1800rpm's but why the bike idle perfect for like 20 - 30 seconds and then shut off without any reason? then it happens after 5 seconds again.

valve clearance is ok.

engine never goes overheated.

all my mods i do to this bike:

3.2 gallon tank from ims,

ufo handguard with aluminium base,

13-48 gearing, (thinking about to change to 14-48)

R&D Flexjet air-fuel mixture screw,

FMF Ti powercore slip on,

smog kit remove, (california model)

moose skidplate,

moose grips,

moose racing radiator guard,

moose racing jet kit stage one,

front and rear springs changed to softer,

stainless steel oil filter,

ignition switch,

front fork bleeder,

rear brake disc guard, (selfmade)

rear brake pump guard, (selfmade)

trail tech vapor computer,

chain slider, (self made)

tires: irc gp110r

ebc brakes,

guts racing soft seat foam,

pics, coming soon.

greets rubio.

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this is my baby.

i think i wil start to change the cdi with my fathers bike to try out if this is the fail. 👍


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Another thing to check is to make sure your tank is venting correctly. If the vent is partially clogged, you may not be pulling enough fuel through at idle.

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thanks for the advice but i dont think its the foult.

i will check it anyway right now but i think if its have not enough fuel to idle then i cant acelerate like an crazy and the bike cant have all the power.

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