2006 yz450f: What are the chances my valves and crank are still good?


31 replies to this topic
  • Justin89

Posted July 13, 2008 - 07:34 PM

#21

Yeah, well Im gonna be having some jetting work done as well...along with the top-end rebuild. So I hope this will freshen things up a bit...anybody got any other suggestions on what I should do to freshen things up?:thumbsup:

  • JSanfilippo

Posted July 13, 2008 - 10:46 PM

#22

I will say one thing ,the the YZ valves straight from the factory should be checked even before starting it. They are so close to the bottom of the spec,I had to shim 2 07's (my personal bikes) BRAND NEW which were a hair too tight.


My old TT-R (apples to oranges I know) and my WR (identical valves to the YZ) were both set right on the tight side of spec from the factory...I think its just a yamaha thing:excuseme: . A few people on here explained thats actually ideal because the cam lobe stays in contact better with the valve through opening and closing therefore reducing the possibility of the valve slamming the seat on closing.

As long as the valves are in spec, I am completely comfortable with them be on the tight side of spec. 1000 miles (about 55-60 hours) on the WR and everything is still up to snuff :thumbsup:

  • mjw1

Posted July 14, 2008 - 04:10 PM

#23

I own a 1999 yz 400f and never had to adjust the valves yet i check them every year and they are still in factory specs like day one. I have only had to replace the top end 3 times the clucth basket. I have well over 5000 hours on the bike.

  • bigred455

Posted July 14, 2008 - 09:21 PM

#24

My old TT-R (apples to oranges I know) and my WR (identical valves to the YZ) were both set right on the tight side of spec from the factory...I think its just a yamaha thing:excuseme: . A few people on here explained thats actually ideal because the cam lobe stays in contact better with the valve through opening and closing therefore reducing the possibility of the valve slamming the seat on closing.

As long as the valves are in spec, I am completely comfortable with them be on the tight side of spec. 1000 miles (about 55-60 hours) on the WR and everything is still up to snuff :thumbsup:


I also like to run on the bottom of the spec,straight form the factory two intakes I forget what 2,but they were sitting at .003. Of course I shimmed to .004 and exhausts .007. I too am comfortable running on the bottom of the spec,especially BIG BLUE OPPS AND WHITE BIKES.Can't forget yellow,:thumbsup:

  • bigred455

Posted July 14, 2008 - 09:24 PM

#25

I own a 1999 yz 400f and never had to adjust the valves yet i check them every year and they are still in factory specs like day one. I have only had to replace the top end 3 times the clucth basket. I have well over 5000 hours on the bike.



Original crank? fantastic,how bout timing chain lets hear it.original owner?

  • mjw1

Posted July 15, 2008 - 03:22 PM

#26

I am the only owner of this bike and the timing chain and crank are stock.

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  • bigred455

Posted July 16, 2008 - 06:06 AM

#27

That is a good report on your bike very good!!! :thumbsup:

  • Justin89

Posted July 16, 2008 - 10:10 AM

#28

That is a good report on your bike very good!!! :thumbsup:


x2:thumbsup: :thumbsup:

  • Wyatt

Posted July 16, 2008 - 03:58 PM

#29

5000 hours.........

I doubt it

  • grayracer513

Posted July 16, 2008 - 04:13 PM

#30

It does strain credibility a bit. The bike would need to have been ridden for a full 3 hours of actual run time every other day since it was new.

500, I would believe.

  • Justin89

Posted July 16, 2008 - 05:00 PM

#31

Maybe it's street legal...?:thumbsup:

  • bigred455

Posted July 16, 2008 - 06:15 PM

#32

Yes I took off a few hrs from 5000 too,but he has ridden the bike to the ground by stating the supposed hrs. 3 top ends and I am sure he went quite a few hrs in between,with no Cam chain alone is impressive and gutsy at the same time.I would have to say the chain would go before the crank.





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