intake valve with no clearance
  • Dan Diego
    Posts: 7
    Joined: Sun Dec 09, 2018 7:59 pm

    intake valve with no clearance

    by Dan Diego » Wed Jan 15, 2020 9:06 am

    I am going to do a valve job on my 07 450r. It has been getting more difficult to start. I check the valves last night and the exhaust valves have .011 clearance. My right intake valve (as I sit on the seat) is .006 but the left intake is .000. I cannot get a feeler gauge between the cam and the valve shim cover (or whatever it is called). I am not sure what would cause of this is. I understand it is likely the valve needs to be replaced. I am hopeful the cam is not damaged but I do not know yet. Is there anything else I should be mindful of or does this seem like a replacement of the intake valves should have me ripping again?
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    JimDirt
    Posts: 3437
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: intake valve with no clearance

    by JimDirt » Wed Jan 15, 2020 1:12 pm

    Yes that sounds like the issue and solution .... when the Intake (mainly , as Exhaust valves are Steel , not Titanium so they do not wear as severe or as quickly) valves start moving , it is only a matter of time before they zero out (no gap like you found) , the only option then , is replacement of the valves and possibly seats ......

    What I would suggest is to (if you are not Pro racing , just play riding or local competitions/practice riding) would be to have them replaced by a reputable machinist (Ken here does excellent work at a fair price) , or at a local shop that is experienced in these engines (ask around , like who the dealer sends their heads to for servicing) and have them install a Stainless Intake kit , including the matching heavier springs .... it will at minimum double the life , if not longer , of the valves , and you (as long as you are not a Pro) will not notice the performance difference due to the difference in weight of the Stainless versus Titanium valves ... (a very slight diminish in RPM , not noticeable by us mere mortals)

    You also need to make sure they either correctly cut the seats (if they cut them too deep , then you will not have a shim small enough to make the adjustment and your head will become a expensive paper weight , because the valve will be sticking up farther into the head which leaves the exposed stem sticking up farther and the gap will be too small for the smallest shim available), or replace them with Beryllium Seats , that will lessen any wear in the future and keep you running for a long time without needing a adjustment ...

    I have the Stainless Intakes (using the stock seats that were cut) in my 450R and my bike is not underpowered or held back by them , and I have not had to adjust the valves since install 3 years ago , my 450X has them (same exact setup , minus the heavier springs , since I do not race this bike) and I have not had to adjust those valves since install in 2006 , that is 14 years without a valve adjustment needed .... (your mileage may vary) ;) ...
    02 CRF450R
    06 CRF450X
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    Weiser , Idaho

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