Tapping sound from newly rebuilt 360 motor
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  1. #1
    Member BerryDuffman's Avatar
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    Tapping sound from newly rebuilt 360 motor

    Finished doing the top end rebuild, also took off the starter and chain. The bike started right up on the first kick and idled, however I heard a loud tapping sound. Sounds like it could be coming from the valve cover, like one of the tappets are hitting the cover? I made sure the cam was lined up correctly with the score mark on the alternator before I put the cam chain back on. Also, the bike didn't easily start a second time, but the carbs may be a little rich. Could this tapping sound just be from the lack of oil in the head, and will it go away after it has a few minutes to circulate the oil? Also I made sure to fill the two cam tubs with oil before putting the cover back on.

  2. #2
    Senior Member HerrDeacon's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    It could be oil issue like you said. I recently started up my 400 and it had a loud ticking/tapping from the head. Turned out there was a blockage in the orifice that feeds oil to the head (between block and cylinders). Hope this is not your issue but could be. Have you taken off the valve cover to check if there is sufficient oil there? Worth having a look before starting again.
    Perry

    1972 Honda CB350
    / 1978 Honda XL250S / 1982 Honda MB5 / 2017 Honda Africa Twin
    Riding Through the Fog


  3. #3
    Member BerryDuffman's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    Looking at the lube diagram in the manual, it shows the path of the oil going up through two rear engine bolts. Does the oil specifically travel inside the bolt and squirt out the top? Or does it travel between the stud and the engine block? I'll manually dump some oil in through the tappet covers, at least that'll narrow down what the cause of the tapping is.
    Attached Thumbnails Attached Thumbnails Tapping sound from newly rebuilt 360 motor-lube.jpg  

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  5. #4
    Senior Member tbpmusic's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    The stud itself is solid.........
    Bill Lane
    Honda Twins Founding Member

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    '75 CB200T, '71 CB450 K4 Half-Breed, '72 CL350 (Sold), '81 CM200T, '72 C70M
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  6. #5
    Senior Member Dirtbag's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    If you didn't put that cam chain tensioner in there properly i.e. it's not sitting in the bottom damper, it'll come out and flop around causing your cam chain to flop around.
    1975 CB360 Gutted Cafe Rat Bike
    2006 GSXR 750
    2 X 1979 RD400 Daytona Specials

  7. #6
    Senior Member Dirtbag's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    1975 CB360 Gutted Cafe Rat Bike
    2006 GSXR 750
    2 X 1979 RD400 Daytona Specials

  8. #7
    Member BerryDuffman's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    See here.
    hmm, I did in fact release the tensioner and heard the spring pop, however I was able to thread and tighten it with a 3mm long screw; I was even able to get the slipper height adjusted. If it did pop out, would I still have been able to adjust the slipper?

  9. #8
    Senior Member Dirtbag's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    Quote Originally Posted by BerryDuffman
    See here.
    hmm, I did in fact release the tensioner and heard the spring pop, however I was able to thread and tighten it with a 3mm long screw; I was even able to get the slipper height adjusted. If it did pop out, would I still have been able to adjust the slipper?
    It would spring up. If your valves are set correctly then i'd be opening up the head cover to have a look.
    1975 CB360 Gutted Cafe Rat Bike
    2006 GSXR 750
    2 X 1979 RD400 Daytona Specials

  10. #9
    Member BerryDuffman's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    Well bad news. That tapping sound was the sound of an engine with too little oil. I only ran the engine twice for 15-20 seconds each, but it seems the damage was done. Checked the compression with my tester and while it may not be completely accurate, it showed sub 90psi reading on both cylinders, both went 30psi-60psi-90psi, and stayed at ~90psi with each kick. Also couldn't get it started today at all. Any advice? perhaps I should find another cheap 360, with a good engine, and try to use the existing parts I already have?

  11. #10
    Senior Member Bird76Mojo's Avatar
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    Re: Tapping sound from newly rebuilt 360 motor

    I know it's been asked before but did you have the chokes OFF/OPEN and the throttle wide open??


    GB
    Doh!

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