My son brought home a 450f basket case!

21 replies to this topic
  • lumpy790

Posted March 14, 2011 - 08:08 AM


Where would the needle bearings come from if it broke a valve spring retainer cap?

Trickle down damage affect.

broken valve retainer = dropped valve = piston thrust into dropped valve = sudden bind on bottom end bearing when everything (piston/valve/head) crashes together. The rod can also be slightly bent.

Needle bearings may not have detectable damage but hairline cracks will come apart in a short time.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • XR133

Posted March 14, 2011 - 08:12 AM


I bought a 2003 YZ450 a little over two years ago in boxes...had a seized crank bearing, which I'm told was common for the year. Put in a new crank/bearings, put it back together and have raced it for two years without touching a wrench to it other than routine maintenance. Just got the head back from MX Time and rode it three hours yesterday and it runs stronger than ever. I would highly recommend MX Time for head work...there is a needle bearing at both ends of the crank. I would replace them if you have the motor out and apart anyway...especially on a bike of this year.

Related Content


Is the 2016 GYTR Yamaha YZ450F too fast? by Fryboy

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

YZ450F 03 Sparks driving me crazy by SirAttard

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

Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

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

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.