Shift fork/drum replacement
  • ImperialPanda
    Posts: 1
    Joined: Wed Nov 13, 2019 7:27 am

    Shift fork/drum replacement

    by ImperialPanda » Wed Nov 13, 2019 7:31 am

    New to the group here!

    I have a quick question.

    I’ve got an 05 crf150f that seems to have a bent shift fork/worn shift drum for second gear. It has trouble going from 1st to 2nd but not from 3rd to 2nd.

    Happens 2 out of 3 times I shift up to second. It doesn’t bother me too much because I’ve gotten used to it, but with the weather getting colder I’m beginning to be more willing to take a couple days tearing it apart to fix it. So here’s what I’d like some thoughts on.

    1. Is a used drum acceptable? What about used forks? I would assume so, but not sure if wear patterns are unique enough to make a difference

    2. While the thing is apart, I plan to put new rings in it, and obviously all the gaskets etc. will be new. But what’s everyone’s take on replacing other top end parts as well?

    3. Is there anything else in the transmission/shift linkage that I should also look at replacing while I do this? I only want to split the block once, so I’d like to do what I need to while I’m in there.

    Obviously I will be inspecting everything to make sure it’s within limits, and this will be done to the highest of standards as I am ocd that way. I’m just trying to avoid down time as much as possible, and want to have everything ready to just get it done in a day or two and not have to be ordering parts mid project if I can help it.

    Thanks in advance!
  • User avatar
    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Shift fork/drum replacement

    by JimDirt » Thu Nov 14, 2019 8:07 am

    Welcome to the site !! \:D/

    You can get used ones , BUT , the only issue is (unless they are local to you) you can't measure the wear/tolerance when you buy on places like EBay , etc. ... That said , if it is not within your budget to buy new , then buying used is the only other option , but you really will not know what you have till you measure everything after purchase , or till you try it and see if it works ......... used has the chance of being in the same condition as yours , so if you are willing to take the chance then go ahead and get used

    As far as replacing other parts (piston , valves , timing chain , bearings , seals , etc.) I would recommend replacing the timing chain at the very least , it is a wear part and often overlooked .... everything else is subjective to what you find upon teardown , basically you need to figure out how many hours you have on the bike , if they were hard or easy hours , and how long do you plan on keeping the bike , etc. ..... If you plan on keeping it "long term" then I would go ahead and replace anything that seems suspect to failure as well as anything that does not measure to specs (I assume you have a manual to check tolerances) , and use the specs as your guide as well as visual signs of excessive or abnormal wear and replace those items accordingly ...(timing chain , rings/piston , seals , always buy new)

    As far as Tranny components to look at , I would also inspect the shift shaft (where your shifter attaches) as more than likely the shifting issue was originally caused by either jamming the shifter with your foot , or from a crash on the shifter side , which could bend the shaft and cause binding and other issues ......

    ........ Basically your budget will determine what you can do as well as your overall goals with the bike .... ;)
    2020 CRF450R
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