Yz426f help!!!!

3 replies to this topic
  • 426yota

Posted April 11, 2010 - 04:46 PM


2000 YZ426F HELP!!!! < SnakesRus > 04/11 17:43:15

My bike is impossible to start.....

I just put a new plug in it and adjusted my carb back to stock specs besides the idle screw, cause i need the bike running to get that right.

Ive heard it might need a valve job.

Ive also heard that it might need to be rejetted due to my FMF Powercore 4 exhaust.

It has great compression, its impossible to kick over at the top of the stroke and I know it gets spark because Ive got it started once and rode it around for a while. When I did ride it I noticed it popped when decelerating, it ran hot enough to start overheating (coolant was coming out of the over flow) and to start melting my side panel at idle (however it didnt have a heat shield like it is supposed to).

Any ideas..

  • grayracer513

Posted April 12, 2010 - 05:49 AM





Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • 426yota

Posted April 12, 2010 - 10:28 PM


ok so i think i figured out the problem

To me, it looks like my cam sprockets are misaligned or they spun a little

Posted Image

The right cam gear looks to tilted just a little bit at TDC and the left one looks to be way off.

How can i tell if they spun versus someone just mis-aligning them on the last valve job?

  • matt4x4

Posted April 13, 2010 - 04:12 AM


Need a pic of your TDC mark on the crank - people tend to get that part wrong.
Apart from that - it looks pretty good - definitely NOT enough out to make it not start.
Your cam chain might be a bit stretched too - this can cause the dots not to line up perfectly.
Both OUTER dots only need to be level with the top of the head at exact TDC.
Turn it a mm or two forward to get the intake dot up a bit and exhaust dot down a bit (they should both come to level with the head surface) and then see what TDC looks like...

Related Content


2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  106 replies

Is the 2016 GYTR Yamaha YZ450F too fast? by Fryboy

Dirt Bike   Special Interest Forums   Pro Racing
  • * - - - -
  • Hot  241 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Need help by Goforaride

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  68 replies

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.