yz450f rebuild question

1 reply to this topic
  • ward63

Posted March 24, 2005 - 06:22 PM


I have just about finished rebuilding my top and lower end on one of my 03 yz450s. it seams like it doesn't have any compression when i kick it over with the cams in. if i take the cams out. the bike has plenty of compression. i know there is the decompression exhaust cam, it seams to be moving smoothly. the bike is so easy to turn over you cant tell when it is at the top of the stroke. it just moves smoothly through everything.

I just complete finished rebuilding my other 450 and had no problems at all. i was going to try to swap the cams from the other bike, but figured id ask before i did that. i only rebuilt the engine because of hours, the engine would start 1st kick every time when i pulled it appart.

any suggestions?

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted March 24, 2005 - 07:12 PM


Double check your cam timing and valve clearances. The auto decomp unit relieves compression from the first 2/3 to 3/4 of the compression stroke. If you have a tight valve or your exhaust cam is retarded, you'll lose the whole of it.

Related Content

WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

YZ450F 03 Sparks driving me crazy by SirAttard

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

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

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 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.