2005 CRF450X wont start with ES but will with kickstart after new top end rebuild with KW SS valve kit
  • 123
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    Joined: Thu Feb 13, 2020 12:05 pm

    2005 CRF450X wont start with ES but will with kickstart after new top end rebuild with KW SS valve kit

    by 123 » Thu Feb 13, 2020 1:42 pm

    Hello,

    I am struggling to figure out why my bike wont start with the ES.

    Prior to the rebuilding the top end, I never had any issues with the ES working. Bike use to fire right up until it was in need of shimming the intake valves until I got to the smallest shim that would fit. Once I got to the smallest shimms i could put in there, it would take a couple min(10 sec pushes and a few sec rest) on the electric start to get the bike to fire guessing cause compression was crap and needed to warm things up. When I did a leak down test cold i was only getting 25% compression and could hear it leaking right through the air filter which is what lead me to do a top end rebuild since I had no idea of the condition from previous owner.

    I just finished a new top end rebuild with new OEM piston, rings, pin, cam chain, tensioner and KW SS valve kit on the head. I put things back together and excited to start the bike and when i try and start with the ES it sounds like its struggling to start. I initially thought it was the battery so I purchased a new lithium battery and installed. After this, starting still sounded the same. Upon initial engagement of the starter it sounds like it wants to take off but then anywhere between 1/2 to 1 turn of the cam seems to encounter some resistance. I also attemted using a optima car battery with ~600 CCA and connected it to ground and bypassing the relay to see if it would have better results and it did not so I think that rules out forking the money for a Shorei battery. I did do a little research and others might say its the cam decompressor adjustment, a tooth of timing off, or the starter motor.

    Exhaust clearance was initially set to .010in since the manual says .011in +/- .001in when initially piecing things back together, but i pulled it apart again to adjust cam decompressor clearance to exact specs per the manual. I set the exhaust clearance to .011in and then set the the decomp clearance to .025in(right ex cl + .014in). Put things back together and same as initial start after rebuild.

    I'm almost certain the timing is not off, but cant rule this out yet. I have checked it at least 3 or 4 times after adjusting with the tensioner applied. Every time I line up the dot on the clutch side cover then come around and check the cam gear, it is spot on with alignment.

    The last thing would be the starter, but I can imagine it when bad during the process of the top end rebuild. It may be possible that the starter never came under the same load as before when compression was horrible allowing the starter to turn the engine over.

    When I opened up the cylinder head cover after the rebuild to check the decompressor system, I did a further inspection of the decomp assembly. First, I noticed that the cam was positioned so the decompressor lifter was at/right before engagement to open right exhaust. Maybe compression was too high here already before the decomp could do its job? Then, I checked the weight/spring again to make sure it retracted after swinging it out facing down to ensure the spring is stringer than gravity of the weight itself and was good there. Finally, I noticed that there was some lateral movement of the decompressor weight. The movement was side-to-side 90 degrees offset from the swinging out and in movement it is supposed to. I wonder if that play makes the decompressor not fully engage? I was thinking about altering the .025in clearance between the ex rocker arm and the decompressor arm to something like .015 but dont know whats safe to do so vs possibly replacing the entire cam decompressor assembly.

    All these parts are expensive and I dont want to just start shooting from the hip and replace the cam decomp assembly, starter motor, ect as It starts to add up real quick!!! I think I am leaning towards a faulty decompressor assembly but dont want to waste money! Any ideas, next steps, or suggestions are much appreciated?
  • User avatar
    JimDirt
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    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 2005 CRF450X wont start with ES but will with kickstart after new top end rebuild with KW SS valve kit

    by JimDirt » Thu Feb 13, 2020 9:27 pm

    Welcome to the site !! \:D/

    Try setting the decompressor gap at 0.013 in. , and try it , and then try 0.015 in. to see if it is any better with either adjustments , and make sure to double check the gap after you tighten the nut down , so you are sure that it did not move , as that can happen when you tighten it , and throw everything off .on the decompressor even 0.001 can make a difference of it starting easier or harder .... Also , check the ground strap where it attaches to the block just behind the clutch actuator , give it a tug , if the wire moves at all in the wire clamp it will affect the starting , as the ground would be weak and make the starter struggle .... if it does move , then re-crimp the wire and try the starter again , it usually gets pulled out when you lift the subframe and go up enough that it pulls on the ground wire ...... those would be the first suggestions if you are 100% positive on the timing . then that would be the first thoughts and where I would check ....

    Only other thing that would come to mind as most likely , would be starter brushes .... or the Starter Clutch dragging (they do go bad) , though if it was working fine before , it is not likely the issue , but it can happen ....

    So try resetting the decompressor and see if you get a different result .....as well as checking the ground ... those would be my first 2 starting points .....report back with findings .... 8-[ :-k
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho
  • 123
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    Joined: Thu Feb 13, 2020 12:05 pm

    Re: 2005 CRF450X wont start with ES but will with kickstart after new top end rebuild with KW SS valve kit

    by 123 » Thu Feb 13, 2020 10:29 pm

    Thanks Jim,

    I'll check the ground cable clamp.

    So just to confirm, you are suggesting I start with decompression clearance of .013in(.011in right ex valve + .002in) to see if that helps then jump up to .015in? Should I not start with the .015in first? Lets say I set the decompressor clearance to .015in and things are peachy with starting, what symptoms would be present to need to increase the clearance?

    Also since i have only ever worked my CRF450X and not any other I have no means to compare another cam decompressor weight lateral movement I mentioned. Do you know if it is normal for there to be minor lateral movement in the decompressor weight?
  • User avatar
    JimDirt
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    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 2005 CRF450X wont start with ES but will with kickstart after new top end rebuild with KW SS valve kit

    by JimDirt » Fri Feb 14, 2020 9:01 am

    No , I am suggesting you start with 0.011 in the right Ex AND 0.013 in the decompressor arm (not 0.011 +0.002 as it sounds like you are suggesting , unless I am misinterpreting what you are saying)... The slightly tighter gap "should" make the engine turn over easier because it is allowing the valve to open sooner and more .... so it "should" start easier due to less compression during starting only... the reason to go to each end (13/15) is to see if there is a significant difference either way (easier/harder for the starter to turn) , this will either eliminate or confirm it is the gap that is the issue and not something else like the brushes or ground or one way starter bearing ...... Check your compression again at each gap

    As far as movement , the decompressor works off rotation , swinging the counterweight out as the engine rotates , any side to side play should not make a difference as long as nothing is extensive enough to cause binding during extension of the weight , possibly causing the weight not to extend fully as it should .... The goal is to get around 58 psi compression , this would indicate the the lash is correct , and its something else causing the slow starter rotation (again assuming the timing is correct)....
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho
  • 123
    Posts: 3
    Joined: Thu Feb 13, 2020 12:05 pm

    Re: 2005 CRF450X wont start with ES but will with kickstart after new top end rebuild with KW SS valve kit

    by 123 » Sat Feb 15, 2020 4:24 pm

    So I checked the ground and was tight enough i could probably hang the bike from the ceiling with it.

    My initial decomp clearance setting was .025in(.011 ex + .014) once i opened it back up the first since my ex was .010 before i made another adjustment that meant decomp cl had been .024 already and didnt work.

    So i started with .023 set and tried, no go.
    Then i tried .022 set and tried and no go.
    Finally, I tried .021in(right ex .011 + .010) and it went brah brah brah!

    I really feel the the decomp weight has too much lateral movement and its not a side to side its more of a canting/yaw. I think the the roller was pushing down on the contact point of the weight and the weight was canting outward making it not engage.

    I think if i was to replace the entire decomp assembly and set it to the .025in(.011ex + .014) per the manual that it would work but I cant justify spending that money when it works just fine now!

    I'm guessing the since the rebuild and I have good compression now is why I didnt have an issue in the past and didnt present itself until now.

    Really appreciate the help!

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