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Bonneville Valve Clearances

Discussion in 'Bonneville' started by MickEng, May 13, 2017.

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  1. MickEng

    MickEng Noble Member

    Sep 29, 2016
    West Yorkshire
    #1 MickEng, May 13, 2017
    Last edited: May 14, 2017
    I am planning the 12k service on my Bonnie EFI and wondered if anyone had any tips on the valve checking and adjustment part of the service.
    From what I have seen it is a reasonably labour intensive strip down to get to the valves.
    Not knowing what size shims you need until you can measure the gaps, are service kits available ?
    I don't really fancy leaving the bike stripped down while I order parts and wait for them delivering.
    I am sure there will be a few on the forum who have done their own valves, so any info would be greatly appreciated.
  2. Smilinjack

    Smilinjack Crème de la Crème

    Aug 14, 2016
    Only done my Kawasaki but l built myself a stock by buying Hotcams shims. Much cheaper than big K and by most accounts better. What size shim does Bonnie use? :)

    PS £2.56 each from Wemoto
  3. MickEng

    MickEng Noble Member

    Sep 29, 2016
    West Yorkshire
    I'm pretty certain they are 25mm dia.
  4. PieMan

    PieMan New Member

    Apr 10, 2017
    Dorset, England
    They are 25mm diameter, but I believe only Triumph sell them in the small increments required.

    If you've not carried out this task before, accurate measurement is all about feel. Get a micrometer and set it to the size of the feeler gauge, lubricate the feeler gauge and slip it in to the micrometer. This will give you the correct sliding feel if a valve clearance is correct. Then, adjust the micrometer to 0.01mm larger and smaller, this will give you the feel of a tight valve and a loose valve.

    The above should help you get accurate readings so you can choose if you need a new shim or two.

    Finally, when installing the cam cover, be sure to use a torque wrench to tighten the four bolts as they shear off very easily.

    Good luck.
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  5. MickEng

    MickEng Noble Member

    Sep 29, 2016
    West Yorkshire
    Cheers Pieman,
    I was getting a bit concerned that nobody else on the forum had ever adjusted their valves.
    I am an apprentice trained toolmaker so micrometers and feeler gauges are like second nature to me but thanks for the tips.
    I always like to prepare myself as thoroughly as possible so I have watched YouTube clips and read up on the job, but there is always something that you can learn from someone who has actually done it.
    I have resolved myself to the fact that if any of the valves do require adjustment after taking the measurements then I will have to order the correct sizes and await postage. Swapping the shims about to bring all valves into tolerance sounds like the most economical way at £6ish a shim.
    It might be that none of them require adjusting.
    Is there any risk of the cam gears springing apart when removing the camshaft ?
    I see that a stepped dowel is required to hold them in situ!
    Lot of bits to come off to get to the bloody things.
    • Like Like x 1
  6. H.O.

    H.O. Noble Member

    Nov 28, 2015
    At least there is no body work to remove Mick!
    I checked mine at 24000mls and no adjustments necessary.
    Whether they had been checked/adjusted at 12000 I dont know, but I've heard its not unusual or unlikely they may well go past 24 to 36000 with out any fuss.
    • Useful Useful x 1
  7. thebiglad

    thebiglad Old fart, still riding !

    Sep 25, 2013
    Central France
    Hi Mick just came across this, don't know if you've seen it yet.

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  8. MickEng

    MickEng Noble Member

    Sep 29, 2016
    West Yorkshire
    Cheers biglad, yes I've seen that video and it is very good.
    Surprised Delboy hasnt done one yet.
    Very interesting post from H.O. though, I reckon if the valves have been set correctly from new and you have changed and used good quality oil at correct service intervals they might not need adjusting. Wishful thinking, but I will check them at 12K for peace of mind.

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