urgent help needed 08 yzf 450

6 replies to this topic
  • bond_yzf

Posted January 08, 2008 - 11:30 AM


i ran my new 08 yz450f in on sunday as follows

20 mins at 1/4 throttle
20 mins at 1/2 throttle
30 mins at 1/2-3/4 throttle

letting the bike cool completly in between sessions

now this was in a flat field

tonite stripped it to check valve clearances the manual says

intake 0.10-0.15
exhaust 0.20-0.25

ive got..

exhaust- 1 valve is 0.18 and the other is 0.20

intake- 2 valves are 0.10 and the other 1 is 0.08

the piston is tdc the timing mark on the crank is lined with the casing mark the dots on the cams are lined with the head and the cam lobes are up and facing opposite...

the clearances are very tight i cant understand how not after run in surely

any help appreciated ....

cheers jim

  • markseaba

Posted January 08, 2008 - 11:35 AM


probably not the help you are looking for, but if this is a brand new bike and the valves are off ALREADY I would take it back to the dealer and have them look at it. See what they have to say.

  • bond_yzf

Posted January 08, 2008 - 11:41 AM


it is brand new its done 1hr run in thats it

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  • grayracer513

Posted January 08, 2008 - 12:26 PM


The .02 mm variance from specification is, in the first place, only .0008" (being charitable). Regardless of your skills, increments of that size are difficult to measure with any accuracy using a feeler gauge, and are certainly not a disaster in the offing.

In the second place, having one or two valves drop out of spec during the first two hours by such small amounts is not at all unusual. As long as the valve will remain at the spec you reset it to over the next two or 3 checks, there is noi issue, and all that you have seen is a valve settling into its seat. Adjust the two that need it, check again in 2-3 hours, and go on with your devil-may-care existence as you were before this came up.

  • bond_yzf

Posted January 08, 2008 - 12:43 PM


so you reckon it just needs futher running in

  • grayracer513

Posted January 08, 2008 - 01:11 PM


I reckon it needs what I said. Adjust the two valves and recheck it in a couple of hours.

  • bond_yzf

Posted January 08, 2008 - 01:29 PM


ok will do cheers

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