04 YZ450F cold start


11 replies to this topic
  • mxdirtking

Posted February 27, 2010 - 06:25 PM

#1

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

  • tek_01

Posted February 28, 2010 - 02:45 PM

#2

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.

  • mxdirtking

Posted February 28, 2010 - 08:29 PM

#3

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.

  • tek_01

Posted March 01, 2010 - 01:22 AM

#4

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?

  • mxdirtking

Posted March 01, 2010 - 11:13 AM

#5

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?

  • tek_01

Posted March 01, 2010 - 12:35 PM

#6

Nothing says you have to change them both

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • kain522

Posted March 01, 2010 - 07:17 PM

#7

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.

  • mxdirtking

Posted March 01, 2010 - 08:40 PM

#8

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

  • kain522

Posted March 02, 2010 - 10:41 AM

#9

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

  • mxdirtking

Posted March 02, 2010 - 11:30 AM

#10

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>

  • kain522

Posted March 02, 2010 - 04:31 PM

#11

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

  • mxdirtking

Posted March 02, 2010 - 07:58 PM

#12

You never know





Related Content

Forums
Photo

Megabomb Fitment by 288yz450


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply
Forums
Photo
Motocross

Thinking about Yamaha 250... by Arctic Pride


Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies
Wiki
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info


Articles
  • 0 replies
Forums
Photo

Snake pit oct 30th by The Anvil


Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies
Forums
Photo

James Stewart back on a YZ450F by YamaLink


Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  47 replies
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.