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mxdirtking

04 YZ450F cold start

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I recently bought this bike and it is the worst thing ever to get started in the cold. After about 5-7 kicks with the choke on it will backfire and then after about 3 kicks after the backfire it will start. I need some help on this one. Thank you

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You are going to need to check a few things first and also specify what cold means, how cold are we talking?

check what size jets you have in there to get a baseline. if the pilot is way off for your weather/alt than its going to be hard to start.

What helps mine (and alot of others) is to give the throttle 2 or 3 twists before you start kicking but dont touch the throttle after that.

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Its like about in the 30's. I checked the main jet and its the stock 165 and its got a pipe on it so im going to have to jet it so i don't know if that has anything to do with it and i'll try that 2 or 3 twists if it helps but right now i got it all torn apart and waiting for parts because the water pump went bad in it.

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I would think the idle circuit would be more of the problem , main jet doesn't kick in until about half throttle, what size was your pilot?

At a guess i would say it should be about 45-48 for that temp and altitude.

It never gets that cold where i live so im not too sure, but alot of others says they need 3-4 twists in extreme cold weather.

Also are the valve clearances in spec?

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Im guessing that it has the stock pilot jet in it. When i change the main jet do i have to change the pilot jet too?

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Cold start on my 04 goes like this- 2 full squirts on the accel pump, full choke, and it will almost always start on the first or second kick. Even after a Wisconsin winter, it will fire in 5-7 kicks. Hope this helps.

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My bike is all torn apart right now because that water pump went out in it but ill try it as soon as i get it put all back togather. I'm in Richland Center half way between LaCrosse and Madison>

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Ok, my in laws are in Mineral Point. Maybe I'll see you on the trails this summer.

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