YZ426 Head

2 replies to this topic
  • mxgene

Posted August 29, 2007 - 02:19 PM


So I decided to replace my piston this week and have two questions,
1: What is the best way to de-carbonize the head without removing the valves (don't have the tool, and I used the solvent test to verify no leak at seat)?
2: After pulling the piston, I noticed what appears to be burns on the crank on either side next to the connecting rod. Is this something to be concerned about?

Thanks in advance for the help.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • 02WR426Cali

Posted August 29, 2007 - 02:32 PM


1. Unless it's caked on real bad, don't worry about it. It will happen again once you run it for a while.
2. I've heard it's from heating up the journals at the factory when they install the pin.

  • grayracer513

Posted August 29, 2007 - 04:20 PM


The heat bluing is indeed a normal part of the manufacturing process. As long as the big end of the rod looks normal, it's fine.

Fill the intake with straight fuel injector cleaning additive, and then use it to clean up the combustion chamber. The carbon will be loosened and mostly flake away as the engine first runs.

Related Content


yz400f throttle bog by yz400fmaniac

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • * * * * *
  • Hot  28 replies

Need help by Goforaride

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  68 replies

100 hrs on 2014 yz450f, shim valves or replace them? by ttr230rider6

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  79 replies

YZ450F 03 Sparks driving me crazy by SirAttard

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 5 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  35 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.