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  • wr/yz expert needed

    anyone know their shit when it comes to wr/yz's
    im rebuilding my 07 wr450 after a screw came loose and 2 others snapped from the balancer weight. ive already replaced all the bearings, new piston and barrel. just trying to work out if i should do the valves also. if they check out to be all in spec just leave them? ive never had to adjust the shims since i got the bike @ 5000'ks its now done 8000'ks, and previous owner only ever had the intake shims changed at 1200'ks.
    i know they're titanium valves so they cant be lapped just want to know if they should be replaced or not
    Last edited by amfrax; 21-06-2011, 11:42 PM.

  • #2
    In spec is in spec. In spec means they are use able. Depends how far you want to go with it, you trying to get it running again so you can use it, or building a top spec motor for your pride and joy or just to last a racing season? All depends.How far are you going with the rest of the motor, what do you want to use the bike for? If its just for your use, id check them over, if they are well in spec and not damaged, use them. If you can get new ones for a reasonable price and you can spare it, may as well throw new ones in, hell go the springs at the same time for the sake of it.
    Not too big of a job to change them out again later on if you needed to or wanted to anyway.
    If its got tits or wheels, it going to give you trouble.

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    • #3
      Im looking at Starting to race supermoto, and the occasional camping away trip. Just can't get my head around what happens if they are in spec and still fail, that brings me to the next question, go titanium again or stainless with springs to suit. I wanna look after it because I want it to last a while, just not sure whether to replace them now or save my $ and wait until I have to do the piston again.

      It's about 350 give or take to replace them either steel or Ti

      Cheers anth.

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      • #4
        unless they have been dropped or had a bashing while in the cylinder there is no reason they should fail. measure up all your specs and spring lengths, if they are all good then they should be healthy and fine to use, if your racing you will probably be redoing it for competition after a season anyway, hot cams and oversize bore etc. Measure up, in spec means your go to go. If they are close to being out, consider new ones. Engines arent as fragile as people first think, i remember being nervous on my first few... dozen... lol :p
        If its got tits or wheels, it going to give you trouble.

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        • #5
          Only thing I've heard about the valves on the WR/YZ is when the Ti finally give up, replace with S/S.
          As said - if they're in spec, then they're in spec - check for run out and mushrooming as well.

          If you want some good advice, have a chat to Gav @ GD Engineering - he rebuilt my WR ground up after my little incident.
          Commander Keen and Shady 7/8 are doing the Kiwi Shitbox rally 2016 as the Dropkick Dropbears- donate here to help us change cancer!


          Originally posted by Martin Luther King Jnr
          One has a moral responsibility to disobey unjust laws.
          . .

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          • #6
            What was your incident?

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            • #7
              Oil pressure check plug....
              It unwinds itself and drains the engine if not nipped up properly. Good excuse to put the 13:1 CP piston in
              Commander Keen and Shady 7/8 are doing the Kiwi Shitbox rally 2016 as the Dropkick Dropbears- donate here to help us change cancer!


              Originally posted by Martin Luther King Jnr
              One has a moral responsibility to disobey unjust laws.
              . .

              Comment


              • #8
                Shadow, i take it you have lockwired it this time? Unlucky anyhow! If any parts are needed or an upgrade is wanted, i have a spare 2011 yz450 engine, just wants a piston and barrel. Seems they dont like really long wheelies :p top and bottom end is all good but the middle bits got a bit close to each other. Otherwise i might have to start a build thread and stick it in my spare klx650 frame mwahahaaa
                If its got tits or wheels, it going to give you trouble.

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                • #9
                  is the 2011 yz injected? how much would you be chasing for the whole motor?

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                  • #10
                    Originally posted by Shadow78 View Post
                    Oil pressure check plug....
                    It unwinds itself and drains the engine if not nipped up properly. Good excuse to put the 13:1 CP piston in
                    where abouts is this? -.- just put my cases togeather.

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                    • #11
                      RHS rear of the head. near where the oil line banjo bolt attaches. its a small 8mm bolt with a copper washer.
                      Lost and on reserve

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                      • #12
                        cool ill be sure to check that its tight. so what exactly happened shadow, it lost oil pressure or drained all the oil out of the motor?

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                        • #13
                          Originally posted by amfrax View Post
                          is the 2011 yz injected? how much would you be chasing for the whole motor?
                          Open to offers, depends if you want it fixed up ready to go, or with the barrel off as it sits right now ready for a big bore kit ;P
                          Yes they are EFI, but mechanically they are the same, the carby and everything will bolt on, older cdi and coil will fire this one just fine/ probably what i will do if i fit it in the klx, maybe use mostly the Kawasaki ignition. Anyways if your interested drop us a PM, im still in two minds wether to do the kawaha or fix the motor and sell it, or sell it in parts. decisions decisions.
                          If its got tits or wheels, it going to give you trouble.

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                          • #14
                            sell it in parts so i can buy the ex cam off you. along with the valves haha, always good to have spares. would be cool to have a spare motor but dont have the funds. what happened to the rest of the bike?

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                            • #15
                              Engine is one i was given to fix, checked it all out, uoted up for the fix, even started on it, but then was decided he will just buy a whole new bike, mine worker, too much coin. so he gave me all the electrics and radiators to sort out my labour and let me keep the motor, and sold the rolling frame to another mate. I had plans to put it into a licenced wr250 frame for a friend but thats fallen through, so now its wrapped in ten layers of gladwrap in my laundry lol until i do something with it.
                              If its got tits or wheels, it going to give you trouble.

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