08 Yz450f Engine questions

3 replies to this topic
  • RWYZ450F

Posted December 17, 2013 - 07:22 AM


Shop says I dropped a valve and it ruined the head. I have probaby 300-350 hours on the bike. They inspected the bottom end and say that there isn't any play in the crank (or is it the rod down there?). With as many hours as I have on the bike, I am afraid the bottom end won't hold up much longer but I base that on a few friends giving me their non-mechanic opinion. If they've inspected the bottom end and say it's good to go, do I have any reason to worry or will it go before it shows any sign of wear? This is my first and only bike and I'm rather uneducated with the engine internals.


I'm not sure I can justify spending more than $1,000 on the repairs. If it rises above that point, my gut tells me to sell it as is and get what I can for it then go get another bike. Or part it out. I expect to hear today or tomorrow from the shop to let me know the damage$$$.


Thanks for your time and input!



  • suzuki son of a bitch

Posted December 17, 2013 - 08:29 AM


If there is no play in the crank then you are good. 300 hours wow. Please do a top end rebuild before a valve or piece of piston chunk off into the bottom end

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  • grayracer513

Posted December 17, 2013 - 11:43 AM


If there isn't any play in the crank, then there's something wrong with it, since there is a specification for how much play there should be.


Nevertheless, the real problem here is that the piston has run into the head hard enough to make a mess of it. That contact may very well have "stamped" grooves in the crank pin and outer rod bearing race, and/or flattened some of the rollers in the bearing.  The crank should be carefully inspected for trueness, and probably torn down for inspection and possible rebuilding.


The head can probably be saved if sent to a competent shop such as EDCo.

  • RWYZ450F

Posted December 18, 2013 - 08:56 AM


Well the 450 is shot. $1,800 is what all the work needed for it amounts to and I'd rather just get a newer Yamaha. I know this might be a new thread question but I'm hoping I can get a quick response from someone who knows a little bit about the 2011.


The shop I took my bike to has a 2011 Yz450f and it looks pretty clean. I'm going to ask them some questions about the previous owner and hours on the bike but otherwise, were there any problems I need to know about with the 2011? I loved my 2008. Never gave me one problem until this so I'd like to get back into another YZ if the newer ones are as reliable as the older. I searched through the first 4 pages of threads and didn't really see any problems noted. Any advice is appreciated.

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