02 yz426 cams hard to turn.


3 replies to this topic
  • boomereed

Posted March 22, 2015 - 11:08 AM

#1

Can anyone tell me how easy the cams should turn on the 426 ? Someone worked on this bike before doing shims and I think they over torqued cam bolts and intake cam seized and jumped time and valves hit piston and bent the intake valves. Intake cam is stiff one journal has minor Gaul ding that I've cleaned up with 600 grit paper. Now it turns but still seems stiff.

  • G-BRO

Posted March 23, 2015 - 11:07 AM

#2

Can anyone tell me how easy the cams should turn on the 426 ? Someone worked on this bike before doing shims and I think they over torqued cam bolts and intake cam seized and jumped time and valves hit piston and bent the intake valves. Intake cam is stiff one journal has minor Gaul ding that I've cleaned up with 600 grit paper. Now it turns but still seems stiff.


I had that same thing happen to my 426 on the intake side. Not being a machinist and wanting to restore the reliability of the bike, I sent my cam caps, cams and head to Engine Dynamics in Petaluma CA. The guys were very helpful. They ended up cleaning up the cam journals, cam cap and polishing the head for 175 bucks. I've got about 30 hours on the bike since with no issues.

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  • boomereed

Posted March 23, 2015 - 05:22 PM

#3

Thanks did they tell you what caused it?

  • G-BRO

Posted March 23, 2015 - 06:34 PM

#4

Thanks did they tell you what caused it?


The two center bolts on the cam cap were over torqued





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