250x shim question
  • Kmaz101
    Posts: 13
    Joined: Wed Oct 21, 2015 9:19 am

    250x shim question

    by Kmaz101 » Wed Dec 16, 2015 9:30 am

    I just have a question about shimming for everyone. when i first got my bike 06 Crf250x) i had the valves shimmed by the local reputable shop, they told me the intake had closed up and they had to put the smallest shim left into the bike. now my bike doesn't start and that same valve has tightened so i decided to change the value myself to stainless intake valves.

    my Question is about the exhaust valves. they have been in spec and not been adjusted the whole time i have had the bike, i read on here that the smallest shims avalible are 1.2mm and largest is 3.0mm so where in that range should i replace the exhaust valves? I am on a budget and don't want to change them if i don't have to. i also don't ride it hard so i just want to know at what point i should change them out, half way? 3/4 of the way? i am not sure what they measure at yet but are noticeable bigger than the intake shims. any feedback would be great!
  • mossman77
    Posts: 316
    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Wed Dec 16, 2015 9:44 am

    If you're exhaust valves are in spec, I don't see any reason to replace them. So you replaced your own intake valves? Did you recut the seats, replace the springs, etc? And your bike runs fine now? Typically this type of job requires a professional shop and specialized tools. Just a little surprised.
    2007 CRF250X
    2004 CRF230F (sold)
  • Kmaz101
    Posts: 13
    Joined: Wed Oct 21, 2015 9:19 am

    by Kmaz101 » Wed Dec 16, 2015 10:43 am

    I've got it all apart, haven't replaced them yet i am just deciding if i should buy new exhaust valves or only do the intake. since intake valves are the ones that give trouble on this bike. i am going to do all the work except cutting the seats etc ill bring that to my local small engine machine shop. i just don't know if lets say my exhaust valves are in the middle of 3.0mm(biggest shim) and 1.2mm(smallest shim) should i replace them while the motor is apart or just leave them?
  • Kmaz101
    Posts: 13
    Joined: Wed Oct 21, 2015 9:19 am

    by Kmaz101 » Wed Dec 16, 2015 10:11 pm

    UPDATE!!!!

    I measured all my shims, with a very high quality micrometer that measures to 10,000 of an inch. funny enough i found one intake at .042in which is 1.06mm, the other was at .073in which is 1.8mm and both exhaust are at .152in which is 3.86mm so almost 3.9mm

    i don't know where the shims came from but as per this web site the smallest you can get is 1.2mm and largest is 3mm. either way, my exhaust shims are above the biggest so does that mean i should just leave them since they have plenty of room to move still? they haven't moves in the last 25 hours (that I've owned the bike) previous to the tear down.
  • mossman77
    Posts: 316
    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Thu Dec 17, 2015 6:48 am

    You measure your intake/exhaust clearance first, and if you find you need to adjust, then you pull the shims, measure, then determine what size needs to go back in. As long as the clearance is within spec, you don't need to worry about the actual shim thickness.
    2007 CRF250X
    2004 CRF230F (sold)
  • Kmaz101
    Posts: 13
    Joined: Wed Oct 21, 2015 9:19 am

    by Kmaz101 » Thu Dec 17, 2015 8:00 am

    yes, my intake was way to tight couldn't even fit a .003 feeler in it, that intake shim measured at 1.06mm so i don't think there one any thinner than that, my exhaust valves were in spec and the shims were 3.8mm
    so my exhaust valves should be fine but the intakes have the smallest shim on one side and a 1.8mm shim on the other side.
  • mossman77
    Posts: 316
    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Thu Dec 17, 2015 8:50 am

    Your exhaust valves are fine, but your intakes are tightened up. You need a valve job my friend. CRFsOnly performs the service.
    2007 CRF250X
    2004 CRF230F (sold)
  • Kmaz101
    Posts: 13
    Joined: Wed Oct 21, 2015 9:19 am

    by Kmaz101 » Thu Dec 17, 2015 8:53 am

    yeah i new about the intakes, i just didn't know about the exhaust but now that I've measured them i know they are fine, whats a good way to clean exhaust valves??
  • mossman77
    Posts: 316
    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Fri Dec 18, 2015 1:53 pm

    You'll send the entire head off for service and they will clean everything up squeaky clean for you.
    2007 CRF250X
    2004 CRF230F (sold)

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