Another Build- 70cc

Discussion in '2-Stroke Engines' started by BoltsMissing, Jun 27, 2011.

  1. BoltsMissing

    BoltsMissing Active Member


    I start with the clutch lever and cover. ( Magneto side )

    The solution is drill out ther lever hole, press in a bush.

    Drill bit size is 15/32

    Bush insert Part No:1020 P10 Wb
    Whatever the numbers mean, on digital vernier the length appears to show
    20mm ( .785 inch)
    or 10mm
    10mm works ok to.

    Outer Diameter shows 12.10mm (.477 )

    Inside Diameter shows 10mm ( .395 )

    The bush ought to be slitted.

    Make a jig so the cover's 3 bolts square up, so it sits in the drill press vice straight.

    Drill in 10mm first, press in the bush then try out the lever.

    Next is the bucking bar and ball bearing replacement.

    I use 2 ball bearings, therefore the bucking bar needs to be shortened.
    To do this so it's not too short, grind one end a little bit at a time.
    Test the length of the bucking bar by inserting the 2 new quality ball bearings in place, and try on the cover.

    Once the cover sits flush with the engine casing, it's the right length.
    Make sure it's not too long, because it can release the clutch as you tighten up the 3 bolts/screws.
    If it's too short, then the cam on the lever may not reach enough to release the clutch. Zero tolerance seems to work ok, it does wear in after some use.
    Use a fine file to smooth both ends of bucking bar, then polish as best as with wet &d ry.

    Case harden both ends of the bucking bar using the heat and fossil based oil method.
    Similar trick ya do after ya sharpened a cold chisel, same principle.

    Do the same on the cam end of the clutch lever, case harden that to.

    Assemble using plenty of hi temp. grease

    This takes care of the sloppiness of the clutch lever, bucking bar and ball bearing issues.

    Why 2 ball bearings?
    Because it works better and longer lasting.

    When I find the camera, I'll post some pictures when using the drill press and the specialy made jig.

    There is not much else that has not been posted.
    I guess matching exhaust gaskets, inlet/carby gaskets.

    I use lots of leather stips where ever possible when mounting the engine.
    Between C-Clamop and engine block. Wrap leather around bike frame.
    This is to dampen the engine vibration and reduce fatigue on the bikes's frame. The ideal is, that no metal ever touches the frame from the engine.
    Some use rubber, old bike tubes. I have found leather has a "feel" about it, lasts longer to.

    Replace as many china bolts as possible and seal up the magento cover so it's water proof.

    Remove burrs from sprockets.
    I don't use kill switch, wires are soldered together and insulated.
    Kit clutch cable is replaced with good quality stainless steel HD brake cable, it only stetches once, initially.

    Inline filter and fuel tap is thrown out, replaced with brass, it is either On or it is Off. All brass. Costs a bit, but so what, it works and lasts longer.

    Throw away plug lead, cos the coper wire is like fairy floss.
    Replace with a real copper plug lead. If it makes the tips of ya fingers bleed, then ya know it's the right copper wire plug lead!
    And lots more mods, already mentioned in many many posts.