Help with timing post valve adjustment
  • wharvey28
    Posts: 3
    Joined: Sun Mar 31, 2019 4:38 pm

    Help with timing post valve adjustment

    by wharvey28 » Sun Mar 31, 2019 4:53 pm

    Good evening all and thanks for taking the time to read/help,

    I purchased a purpose built 2009 CRF450R supermoto last October and just recently had the chance to take it out for the very first time ~3 weeks ago. With the riding season coming up quickly I wanted to get a round turn on all maintenance items I wasn't sure of with one of them being the valve clearance. I at least wanted to check them to document clearances. The clearances I measured were as follows:

    Exhaust: L: 0.010"/0.254mm R: 0.011"/0.279mm
    Intake: L: 0.003"/0.076mm R: 0.006"/0.152mm

    With everything except the left intake in spec I decided to change it out. I used the formula:
    New Shim Thickness = (Recorded Valve Clearance - Specified Valve Clearance) + Old Shim Thickness.

    or,

    (0.076mm - 0.152mm) + 2.1 = 2.024mm, so I ordered a 2.00mm and 2.05mm HC shims and decided to drop the 2.00mm shim in to see if that was the magic number.

    In doing so, I knocked the screwdriver and vice grips I had set up releasing the pressure on the cam chain tensioner. I quickly put it all back together but I'm thinking I'm off a tooth or more on the bottom end of the chain.

    I've gotten it all back together, torqued back down, and cam chain tightened back up and am getting readings where the exhaust clearances are extremely tight ~0.003" and the intake clearances are extremely loose ~0.011". I've tried lining up the timing as far as the factory service manual goes (yes I do have one and still need help) and can't get it right for some reason. The cam gear is an APE adjustable gear and doesn't have the nice lines across it like the stock gear does. It does have two dots and I have those lined up with the head and cam journal but still no cigar. I've tried advancing/retarding a tooth or two teeth in both directions and still can't get much of a difference on clearances.

    Any ideas on what I could do to remedy this or something I may have overlooked? I'm about to pull my hair out over it.
  • User avatar
    JimDirt
    Posts: 3341
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Help with timing post valve adjustment

    by JimDirt » Mon Apr 01, 2019 12:47 pm

    Welcome to the site !! \:D/

    Since you have a aftermarket cam sprocket , do you by chance still have the OEM one ?? , you could align that one in front of the sprocket you have to see if/where any marks align to help with locating the correct cam position in reference to the head ..... regardless of that , the cam needs to be at the 2 o'clock position to get the valves with no tension , you do not need the timing chain involved to get this adjustment , you can adjust the valves while the chain is off (like when "bench shimming" with just the head sitting on a bench) , so do not worry so much about the timing chain aspect of it to get proper clearance , as long as when you are checking the clearance that the cam is in the correct position (2 o'clock facing the rear of the head) , as the clearance is the clearance , it will be the same with the chain on or off

    With that said , you need to establish where the level marks would be on the aftermarket sprocket in conjunction with the OEM sprocket , the alignment "should" be in the center of the slot , so I would use that as your guide , as a aftermarket sprocket would allow both advance and retarded timing , so "stock" should be centered in the slot , If you want to keep the current (advanced or retarded) timing of the aftermarket sprocket , then just mark it where it is currently set with a Sharpie or a paint pen , and then loosen the bolts and center them in the slot , and just snug them so you now have the reference you need , again , matching the aftermarket sprocket to the OEM one would be optimal for accuracy , then check/set your lash , then when re-assembling , adjust to the desired timing ... but the chain being a tooth or more off will affect where the cam is positioned in accordance to zero , so if the clearance was checked with that sprocket , where you got your prior readings with all the other marks aligned , then you should get the same reading on the shim you did not replace (assuming you only replaced the tight one) , so the clearance on that one should remain unchanged , so you must establish the correct alignment by using the OEM sprocket , then you know you are in the correct position to check the clearance first , this is imperative that you establish where the cam is aligned with the head BEFORE worrying about clearance

    Have you tried moving the cam back/forwards a little and checking the clearance to see if anything resembles the original settings (on the shim you did not replace) ?? , this might help with getting to the original position (this all assumes you removed the sprocket when removing the tower , thus changing the position of the cam to sprocket alignment) as moving the cam back/forth will show the greatest gap , when you get the largest gap , you should be in the correct position

    Then , when you reset the chain , all the other marks should be aligned , and it should be in time again
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho
  • wharvey28
    Posts: 3
    Joined: Sun Mar 31, 2019 4:38 pm

    Re: Help with timing post valve adjustment

    by wharvey28 » Thu Apr 25, 2019 12:59 pm

    Alright, so it's been a while...waiting on different parts/gaskets and what not but the valve adjustment was an easy fix. I'm an idiot and switched the exhaust shims with the intake shims even though I thought I had it all laid out perfectly. Switched them over...boom perfect clearances. Only issue now is that the crank is extremely hard to turn over by hand and almost impossible to kick start. Like I feel like I'm going to bottom out the suspension with all the force I'm putting into it and have to put my MX boot on to even think about giving it a kick. Is this just a timing issue or did I screw something else up? Once it's started it runs fine, haven't taken it on a lap around the block or anything but seems to idle and rev as it should.
  • User avatar
    JimDirt
    Posts: 3341
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Help with timing post valve adjustment

    by JimDirt » Thu Apr 25, 2019 10:33 pm

    Alright, so it's been a while...waiting on different parts/gaskets and what not but the valve adjustment was an easy fix. I'm an idiot and switched the exhaust shims with the intake shims even though I thought I had it all laid out perfectly. Switched them over...boom perfect clearances. Only issue now is that the crank is extremely hard to turn over by hand and almost impossible to kick start. Like I feel like I'm going to bottom out the suspension with all the force I'm putting into it and have to put my MX boot on to even think about giving it a kick. Is this just a timing issue or did I screw something else up? Once it's started it runs fine, haven't taken it on a lap around the block or anything but seems to idle and rev as it should.
    Make sure the decompressor is working correctly (on the end of the camshaft at the sprocket) , make sure its springing back , it should return easily , there is a pin also on the shaft of the cam at the lobe for the exhaust valve , make sure it moves in/out with pressure , this is what releases the exhaust valve a little and allows the compression to drop when kicking , as soon as the engine fires the decompressor kicks in from centrifugal force and allows the valves to close fully bringing back the compression ..... its most likely the cause of the heavy foot needed to kick it if its sticking ... ;)
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho
  • wharvey28
    Posts: 3
    Joined: Sun Mar 31, 2019 4:38 pm

    Re: Help with timing post valve adjustment

    by wharvey28 » Fri Apr 26, 2019 9:45 am

    You nailed it Jim. I ran across another post after posting my last reply and decided to give the decompressor a check. Sure enough the spring wasn't hooked onto the weight. Must have come undone while I was being careless and frustrated trying to get the valve shims sorted out. Got it back on correctly and everything put together. Started after a few easy kicks and running great. Thanks for all the help!!
  • User avatar
    JimDirt
    Posts: 3341
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Help with timing post valve adjustment

    by JimDirt » Fri Apr 26, 2019 11:01 am

    No problem , glad I could help , that is what this place is about , helping other riders keep riding ;)
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho

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