04 YZ450F cold start

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

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.

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.

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?

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?

Nothing says you have to change them both

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.

Nice! Its better info when someone knows the Wisconsin winters!

Did it work for you? Where in Wis are you? I'm in Waterford.

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>

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

You never know

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