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Thread: low fuel mileage on 88 K75C

  1. #16
    Registered User rall275's Avatar
    Join Date
    Apr 2017
    Harrisburg, IL
    I'll archive your info here and compile it all when I'm ready for the action. Plugs good, the typical bosch x5dc. I thought to rotate the cams/valves you used a 19mm wrench as in that youtube video of the guy checking K100 valves? When one intake cam lobe is pointing away from the valve, is it in a slightly upward angle from the horizontal? Also, when an intake lobe is ready for clearance checking, is always one exhaust ready for checking?

    I don't have a caliper, but I'll get one.


  2. #17
    3 Red Bricks
    Join Date
    Jan 2007
    Pleasanton, Ca.

    You CAN rotate the cams like in the videos, but the way I described is WAY easier and just as accurate. Your choice.

    Since early K bikes have hemispherical combustion chambers (yes, it's a HEMI !!!), the valves are canted towards each other. That means that the upper intake valves are angled down (towards the spark plugs) and the lower exhaust valves are angled up (towards the spark plugs).

    The appropriate position for checking a valve is when an intake lobe is pointing directly away from the valve (at an angle slightly ABOVE horizontal) and an exhaust lobe (different cylinder) is pointing directly away from its valve (at the same angle slightly BELOW horizontal).

    Cranking with a wrench allows you to stop anywhere and go past the ideal spot. Backing up (turning in the direction opposite engine rotation) is not advised as chain slop is not accounted for.

    Bumping the starter (with the plugs in!) will put you in the correct spot (or occasionally stop so far off that it is very obvious). Try both ways (wrench vs starter) before you start checking the valves and decide which way you'd prefer to use.

    One of the advantages of using the starter is that you don't waste time removing and reinstalling the spark plug cover plate, the spark wires, and the spark plugs.

    One disadvantage is that you are not inspecting your spark plugs as often. But you're going to need to recheck your valves several times before a new set of plugs will need any attention.


    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  3. #18
    Registered User rall275's Avatar
    Join Date
    Apr 2017
    Harrisburg, IL
    thanks for the advice. Will look into both methods.

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