CRF450X Valve Shims
  • rjmuffler
    Posts: 4
    Joined: Sun Mar 25, 2018 1:36 pm

    CRF450X Valve Shims

    by rjmuffler » Sun Mar 25, 2018 2:18 pm

    I have a 2005 CRF450X I have had since new. In 2017 it became hard to start. The problem turned out to be valve clearance. After replacing the valve shims to get it back to the proper clearance as called out in the service manual it ran good again. Unfortunately it became hard to start again just 5 months later (about 5 days of riding). Again the problem turned out to be valve clearance. Replacing the shims to get back to proper clearance got it running well again. I am concerned about the rather short interval between the first and second times the valves needed to be adjusted. Can anybody shed any light on the reason for this?
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    JimDirt
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    Joined: Sat Nov 25, 2006 6:31 pm

    Re: CRF450X Valve Shims

    by JimDirt » Sun Mar 25, 2018 7:08 pm

    Welcome to the site !! \:D/

    The reason is the valve seat is harder than the valve face , and as it is slammed shut if there is even a trace of dirt on the face it acts like a grinder , and cuts away the face of the valve , as it wears your gap decreases , to the point where it zero's out , eventually to the point where you can't find a shim small enough to fit the space , because as the face wears , the valve moves closer to the seat

    Basically once the valves start moving they are on their way out and will need to be replaced along with the seats being recut or replaced , mine went at about 6 months from new (in 06) from dirt getting past the filter , so i went to Stainless Steel valves instead of Titanium and have not had them go out of adjustment since , this is what most people do , you can buy a replacement head ready to go with new valves and seats from here , or you can find someone local , (or have it done here) replace the valves and cut the seats , just make sure they are proficient in doing modern 4 strokes , they are different than cars and need special tools made specifically for doing these engines , it wont be real cheap , but once its done you can ride for a long time without any issues ....... The key is to make sure the air filter seat is clean and sealed at the face , the dirt gets past the filter if its not oiled or seated properly and it takes out the valves , its a expensive way to learn filter maintenance , but its a real common issue

    This will give you a idea of cost , for doing the valve job , or just replacing the head

    https://www.crfsonly.com/catalog/index.php/cPath/258

    Sorry to give bad news , but basically , you will need to either replace the head or replace the valves , or you could try a used head on eBay , but may end up with the same issue fairly quick and be out more money ....
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • rjmuffler
    Posts: 4
    Joined: Sun Mar 25, 2018 1:36 pm

    Re: CRF450X Valve Shims

    by rjmuffler » Thu Mar 29, 2018 2:32 pm

    Well that makes sense. I've always tried to be careful with the air filter both with the oil on the foam and greasing the seal, but I must have not done a good job at least once. Thanks for the insight.
  • rjmuffler
    Posts: 4
    Joined: Sun Mar 25, 2018 1:36 pm

    Re: CRF450X Valve Shims

    by rjmuffler » Thu Mar 29, 2018 2:39 pm

    You mentioned that I could have the head rebuilt there with stainless steel valves. I couldn't tell from the link you provided which option that was. Could you point to which option and also indicate how long the turn around time would be?
    Thanks.
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    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: CRF450X Valve Shims

    by JimDirt » Thu Mar 29, 2018 2:59 pm

    Yea just look here https://www.crfsonly.com/catalog/index. ... th/258_275 , it gives prices which vary depending on work done , each case is different depending on what is wanted or needed and what your budget will allow , you can Private Message Ken the owner here and he can give you more detailed info specific to your needs , as there are many variables , all the prices on the link with the exception of the first one (CRF150) will be for the 450 , there are variables depending on the brand of Stainless valves , different Seat material , etc , which is why talking to him directly , would get you the info you seek (I don't "work" here so I can't give you specifics , I am just a old bum that hangs out and likes posting in the forum) ... But you won't be disappointed with the quality of his work ...

    Here is the link to contact Ken , just go to it , then click on where it says PM: Send private message , he usually replies pretty fast

    https://www.crfsonly.com/forum/memberli ... rofile&u=3
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
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    crfsonly
    Owner
    Posts: 9651
    Joined: Thu Apr 01, 2004 3:45 pm

    Re: CRF450X Valve Shims

    by crfsonly » Tue Apr 03, 2018 6:04 pm

    To agree and add to what Jim said, titanium is a very soft material compared to valve seat materials. Titanium valves are therefore surface hardened. The surface hardening wears from two factors, friction (as Jim mentioned) and heat. Excessive heat, for lack of a more precise term, carbonizes the surface hardening treatment causing premature reduction in the surface hardness of the valve making it more susceptible to friction wear and deformation from valve seat contact. At this point the valve will deform as it sinks into the valve seat increasing the valve stem protrusion resulting in reduced lash. This process accelerates as the surface hardening treatment reduces further until it's raw titanium against the stock powder iron valve seats.

    This is why for titanium valves we replace the stock valve seats and valve guides with material that reduces valve heat significantly. Matched with high quality titanium valves with our seats and guides will last significantly longer than the stock titanium valves. However, this is a significantly more expensive solution to increasing valve life. Heads we build for top level racers opt for this solution for all four valves as they are looking to maximize valve performance while increasing valve durability.

    The lower cost alternative is stainless steel valves. Quality stainless steel valves are much harder and their hardness is consistent throughout the valve. Hence they are inherently more durable and are not negatively affected by the stock valve seats and guides.

    Ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
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    CRF Parts and Accessories: http://crfsonly.com
  • rjmuffler
    Posts: 4
    Joined: Sun Mar 25, 2018 1:36 pm

    Re: CRF450X Valve Shims

    by rjmuffler » Tue Apr 10, 2018 5:19 pm

    I have the head removed from the bike now. I'd like to go head with reworking the head with the stainless steel valves for durability. Please let me know how to proceed.
    Thanks
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    crfsonly
    Owner
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    Re: CRF450X Valve Shims

    by crfsonly » Tue Apr 10, 2018 5:47 pm

    I have the head removed from the bike now. I'd like to go head with reworking the head with the stainless steel valves for durability. Please let me know how to proceed.
    Thanks
    If this was directed at me, order the valve job service you want online and then we'll send an email with instructions on what to send and where to ship it.

    https://www.crfsonly.com/catalog/advanc ... =valve+job

    Ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
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