2008 CRF450X Won’t start, Timing, After Valve Clearance Adjustment
  • BRWEIDEM
    Posts: 9
    Joined: Wed Mar 14, 2018 7:46 am

    2008 CRF450X Won’t start, Timing, After Valve Clearance Adjustment

    by BRWEIDEM » Mon Oct 19, 2020 9:58 am

    Hi,

    If this is not the correct location let me know and I’ll move it.

    I’ll be brief and provide as much pertinent info as possible.

    2008 CRF450X purchased used several years ago. Bike was immaculate with no signs of abuse. Never had any issues with it running, I did perform all the recommended air box and carb changes once I bought it. The ‘pink wire’ has been removed from the connector. Stock header, FMF powercore silencer. Trail tech high output stator to power Baja designs squadron pro light. Other than that, bike is stock.

    Pulled the tank to change spark plug and decided to check valve clearance at that time. Intakes were in spec and exhaust measure .09 and .11 mm compared to .28 per the manual. My failure, I did not take note of any timing marks before disassembly as I have the shop manual and was confident I could line everything up per the manual during assembly. I changed the shims and found TDC on the right clutch side view hole, then proceeded to line up three things per the shop manual. 1) dash mark on the cam sprocket to the arrow mark, 2) decompressor pin to the weighted arm on the cam sprocket (2008 has a sort of auto decompressor mechanism that resides on the cam sprocket. A pin on the decompressor shaft lines up with an opening on the weighted arm), and 3) the cam sprocket bolt holes line up with the camshaft. With the TDC mark on the right clutch side view hole lined up and these other three lines up on the cam and sprocket I continued with assembly. I am 100% sure these were all lined up. I checked and triple checked. Once assembled I went to start with the electric start and something sounded different. No hard metal noises just difference in the starter motor sound. No start. I hopped up on it and tried kicking and the stroke through the kick starter felt different. This, with the change in sound on the electric starter led me to believe it was timing related. I pulled the left side view hole to check marks on the flywheel. I rolled though the entire cycle several times and did not see any flywheel marks to compare my previous timing line up to. My next step is to pull the flywheel cover, but aside from that I am at a complete loss. Per the shop manual I only needed to line up the right side TDC punch mark and the cam line up marks and that’s it. Is the manual missing a step? Am I missing something easy? This is my third CRF450 and don’t remember running into this. I’ve seen other similar threads about the 450X but didn’t see any clear resolution on those threads. Any info is appreciated.

    Thanks.
  • Back2-2
    Posts: 1148
    Joined: Tue Jan 04, 2011 3:31 pm

    Re: 2008 CRF450X Won’t start, Timing, After Valve Clearance Adjustment

    by Back2-2 » Mon Oct 19, 2020 1:17 pm

    Trying to get a handle on what you have going on.
    My guess is that you were not at true TDC. There is TDC twice in a engine cycle - if that makes sense. I suggest starting completely over from the very beginning. You may have inadvertently done all your adjustments on the exhaust stroke?
    The compression release is also very sensitive and a little off can really make a difference in starting.
    Neil
    Black Hills of SD
    Life without Motorcycles would just be boring, really boring
    Honda 450X. Yamaha Tracer GT900. HD Fat Boy. Triumph Bonneville. Yamaha Majesty 400. Yamaha Grizzly. Yamaha Wolverine. Yamaha TW200
  • BRWEIDEM
    Posts: 9
    Joined: Wed Mar 14, 2018 7:46 am

    Re: 2008 CRF450X Won’t start, Timing, After Valve Clearance Adjustment

    by BRWEIDEM » Mon Oct 19, 2020 2:44 pm

    Thank you for the prompt reply.

    I thought about that also. However, the more I thought about it the more I realize that without a timing chain connected, you cannot really identify any stroke. The piston at this point is simply moving up and down. Only when the timing chain is connected do we now start to identify what the up-and-down strokes actually do. For example with the piston at top dead center and the cam lobes facing towards the rear of the bike, we’ve now assigned that top dead center the top of the compression stroke Instead of top dead center of the exhaust stroke. I wondered if maybe the engine only fires on one top dead center and I have assigned the wrong top dead center to the compression stroke. However, after reading some other forums it sounds like this motorcycle fires at every top dead center, with one wasted fire at the top of the exhaust stroke. Is this true? I Truly don’t know. That’s why I was wondering about the marks on the fly wheel. However when I looked through the left side view hole I don’t see any indicating marks on my fly wheel.

    I haven’t put much thought on the decompression mechanism. I’ve seen a YouTube video regarding the older CRF mechanism. Mine being a 2008 model, the decompression system looks pretty straightforward. There is no adjustment for it. The manual simply says to operate the mechanism with your finger as long as it opens freely and closes under spring tension it is good to go. I can look a little more into this when I get home today.

    If I am way off base in anything I am thinking here, please feel free to let me know.
  • Leardriver
    Posts: 462
    Joined: Wed May 05, 2010 10:33 am

    Re: 2008 CRF450X Won’t start, Timing, After Valve Clearance Adjustment

    by Leardriver » Sat Oct 24, 2020 3:30 pm

    The mark on the right side that you remove the plug to view never looks right on to me. Before I take the cam sprocket bolts out of any bike for the first time, I line the left side marks perfectly and put a punch mark on the right side marks where my eye thinks it lines up.
    A perfect valve lash is .005 intake and .009 exhaust. The manual dumbs it down to keep engines from breaking and ruining Honda's reputation.
    If the marks are lined up, and the cam lobes are up and towards the back, you should be close. I can't tell you how easy it is to be one tooth off ](*,)
    Did the bike start before you adjusted the valves?
    These bikes make a spark every time the piston is at the top, called a wasted spark ignition. Only by putting the cam chain on the sprocket do you establish which piston voyage up and down has become TDC on the compressions stroke.
  • BRWEIDEM
    Posts: 9
    Joined: Wed Mar 14, 2018 7:46 am

    Re: 2008 CRF450X Won’t start, Timing, After Valve Clearance Adjustment

    by BRWEIDEM » Mon Oct 26, 2020 7:50 am

    Leardriver,

    Thanks for the reply. You confirmed a couple of things I had questions about that I received mixed feedback on.

    As mentioned previously, I failed to notice where the marks were prior to disassembly. I figured since I had the manual it didn’t matter where they were prior to disassembly. However, in hindsight, it is good practice to make note of these things prior to disassembly and I wish I would’ve done that. It would’ve saved a lot of grief.

    There are MANY posts on CRFsonly regarding this very thing. I found one where the guy mentioned he lined everything up to the left side second mark and I thought what the heck I’ll give it a try. I called my brother over to help since it’s difficult to turn the crank on one side of the bike and view through the left side flywheel hole at the same time. We slowly turned the crank until I was lined up on the left side second mark, set up the cam sprocket and chain while on the second mark, put everything back together, and sure enough she fired right up. I couldn’t believe it.

    Since I didn’t know if this was going to work, I didn’t check to see where the right side mark was when I was lined everything up on the left side second mark. However, I can assure you it’s not close. At least not within the range of, “well, I think it’s close.” I do plan on opening everything up and seeing how far off these marks are. However at this time I’m just glad it runs the way it should.

    A Google search of ‘2008 CRF 450X timing’ will bring up many CRFsonly and thumpertalk posts on the subject. Reading through these is difficult because there are so many and not all of them provide a solution. However, after my trials and errors I can say that performing timing off ONLY the right side punch mark per the Honda service manual will not result in a running bike. The timing will be off and the bike will not run.

    To anyone with knowledge on this:

    Why is there no mention of opening the flywheel view hole cap and instruction on performing timing off the second flywheel mark in the Honda service manual?

    Rocky Mountain ATV has a YouTube video that shows how to adjust valves on a CRF450R. It mentions briefly that the flywheel view hole cap needs to be opened up but does not go into detail about how to use this for timing. Another missed opportunity for clear instructions on how to time these things.

    Lastly, if others have run into the same issue and have resolved it the same way I did, post it here and let me know. Or if you had a different experience, let me know. If there is enough consensus I think this should be a sticky topic or a major topic somewhere on the CRFsonly site.

    I’m open to all feedback here so let me know what you know.
  • Leardriver
    Posts: 462
    Joined: Wed May 05, 2010 10:33 am

    Re: 2008 CRF450X Won’t start, Timing, After Valve Clearance Adjustment

    by Leardriver » Wed Oct 28, 2020 6:38 pm

    Why is there no mention of using the much more accurate left side timing mark inside the removable plug?
    Dealerships love easy work, and this is one of the secrets.
    Good job solving the problem. Getting the timing marks wrong happens all of the time, and a little practice helps.

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