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Help Cam timing after valve clearance - CBR250RR MC22

Discussion in 'Honda 250cc In-line 4's' started by Crepsley, Mar 18, 2022.

  1. Crepsley

    Crepsley Active Member

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    Hello all! After a long time coming (2yrs) I’m trying to get my valve clearance finished, I got it started for the first time in the 2 years. Pretty much at the last steps of my minor restoration( basically getting it in better condition and servicing) did the valve clearance checked over so many times cause it was my first time doing it, got it all in spec replaced about 12 shims checked another however many times - got it started the other day finally and was very rattling.
    Took it apart again (kill me) rechecked it all 3 were out again, how! 2 IN were at 0.9 (same cylinder) , they had non existent gaps before it all, and 1 EX was at a whopping .32 gap.
    Now I’m questioning the cams as I couldn’t get them perfect before and not now either, they line up parallel to each other but can’t get them to line with the T in the inspection hole.
    Also a weird sort of air escaping noise when turning engine over by hand.
    I’ll post some videos and photos to see if someone with at least some mechanical knowledge can help cause I don’t have any. Thank you :)
    https://imgur.com/a/rXzuYjR
     
    Crepsley, Mar 18, 2022
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  2. Gen

    Gen Well-Known Member

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    I hope you are not using the "F" mark to set your cams ? (pic), use the "T"
    It's always a bit daunting, you have to allow for the cams rotating slightly as you tighten down the cam cap bolts, then there's the "scissor" part of the cam gears (they control the backlash).
    I figure you are tightening the cam bolts down evenly (working back & forward progressively as the cams are pulled down (slowly & evenly) , or you would have snapped a cam into 2 pieces by now (common mistake)
    Also, triple check the shims are sitting squarely on top of the valve stem (they can jam cock eyed & stuff up your clearances,even bend a valve, then "POP" into their correct position when turning the engine over when you test run the bike, instant noisy excess clearances appear.
    Tiny
     
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    Gen, Mar 19, 2022
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  3. Crepsley

    Crepsley Active Member

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    Thanks for the reply, yeah im using the T and evenly tightening them down, always careful with everything. Just can’t line them up with the T
     
    Crepsley, Mar 19, 2022
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  4. Gen

    Gen Well-Known Member

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    Try putting the cam marks facing out,that lines up the other cylinders (1&4, or 2&3 & It'll make it easier to line them up with the head surface) & remember to allow for the cams rotating as you pull them down, Iv'e done cibbie cams too many times to remember, but still stuff up occasionally .
    You will notice the cam rotating as you tighten them down, so they should NOT be lined up before you tighten, practice will get you there ;)
     
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    Gen, Mar 19, 2022
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  5. Crepsley

    Crepsley Active Member

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    Yeah I lined them up facing away from each other, just for the photo put the facing inward. The T lines up exact same spot when lining up outward.
    Tried allowing for the spinning when tightening down, probably redone it 10 times now, takes so long as well each time!
     
    Crepsley, Mar 19, 2022
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