Discussion in 'Motorbike Technical Discussion' started by Lukeb1961, Apr 14, 2012.

  1. Lukeb1961

    Lukeb1961 Guest

    http://cid-407d7ef0965d3991.skydrive.live.com/browse.aspx/JR50 Suzuki

    Frequently Asked Questions

    The Suzuki JR50 was manufactured from 1978 through to 2007.
    The Kawasaki KDX50 of 2002-2006 was the same machine, with green plastics.

    The 1978-1982 bike was effectively identical apart from stickers.
    The 1983-1996 bike was effectively identical apart from stickers.
    The 1997-2007 bike was effectively identical apart from stickers.

    There were minor variations such as front number plate, stickers,
    or plastic tank, seat cover, fork springs or swing-arm, but each
    cluster was pretty much identical for at least 5-7 years. The vast
    majority of parts were unchanged for the entire range and are
    interchangeable. The basic engine was also used in the ALT50 and LT50.

    Your engine number is on the engine case, at the base of the barrel, front

    24 degrees BTDC @ 3000rpm. NGK BPR4HS - gap 0.6mm (0.025 in)

    Points gap should be set to 0.3mm (0.012 in) (if an early model with points,
    of course!)
    if hard to start but will start and run HARD if clutched, you have the
    timing wrong!
    i.e. reset the points gap - closer. You are opening too early and the
    maximum is 0.4mm (0.16 in)

    If possible, get a dial gauge and meter and ensure it opens exactly when the
    mark aligns with the notch on the cover.
    Timing light shining on the mark will show if you are out.
    If always hard to start and everything else is spot on, replace points. If
    still no good, replace condenser.

    If all is correct, you should be able to walk up to a cold machine, flip the
    choke on, touch NOTHING and kick it.
    It will start first or second kick. YES, really.

    CLUTCH adjustment
    Take the clutch cover off - note engine oil dripping onto your feet.
    Loosen locknut. Run the centre screw in until it just pushes the plate (you
    will feel it)
    You should see the mechanism try to move. Tighten locknut.
    Too loose and it will not turn the engine over.
    Too tight and the kick-starter will not return.

    HINT, when you push the kick-start lever, you will see an arm rotate the
    clutch mechanism and push the clutch inward a few mm.
    This is engaging the clutch to kick it over. If you do NOT see this
    occurring, you may have inadvertently put the outer release plate on the
    wrong way.
    The nipples on the plate should fit into the areas on the inner plate, ie
    point INTO the engine, not out.

    Idle @ 1400rpm, engages @ 2500rpm, fully locked @ 3000rpm.
    Do minor adjustments to suit your little person.
    Adjustment of the clutch is recommended so that the bike rolls freely in
    Yes, in gear you can push it and not turn the engine over. That is how it is
    meant to work.
    This lets the motor gain a few revs before engagement and makes the shift
    into gear smoother.

    Add oil to engine again...
    Test by starting up, letting it idle and pushing into 2nd.
    It should NOT move off until the throttle is turned.

    Mikuni VM12SC, float height 25mm, air screw 1-1/4 turns out
    Make sure you fit a fuel filter! They did not come with one.
    if fuel is coming out of the overflow pipe too much, you have float setting
    too low, e.g. 23mm instead of 25mm.
    Yes it has two tiny little pilot jets, not one!. Blow out the tiny jets,
    blow out the main, blow out the other two holes.
    If you remove the bottom of the two tiny pilot jets, it will go rather
    Also, adjust the throttle cable up at the handlebars to remove any slack.

    Today's 10W/30 (SAE80W) motor oils are ideal.
    There is a bolt in the side of the r/h case. Remove; fill until it comes out
    of the bolt hole.

    The CCI injection container is for boring normal 2-stroke oil.
    Fuel should be plain high-octane unleaded. NOT premixed.
    DO NOT run the JR50 on premix!
    The bearings get fed directly via the CCI. It works, it's easy.

    Clean out the exhaust - it gets blocked with crud with age.
    Compression test should be circa 100PSI.
    There may be restrictor plates between carburettor and head.
    Also in head to exhaust - remove them.
    Give it a new plug and fresh fuel.
    The pilot jet is actually two. One tiny and one absolutely microscopic. One
    atop the other.
    The smaller one can safely be removed to give slightly more power.

    1st GEAR
    Yes, there are two gears in there.
    Transmission is 2nd-neutral-1st (down-is-second, middle is neutral,
    However the 1st gear selector is blanked-off normally. 1st is a very low
    Pull the right side cover off. With the cover off you can look at the shift
    The flat arm has a rectangular slot that is only half-width, rather than
    You'll see where the section has been blanked off.
    It's got an oblong cut one way. Make a second oblong space the other way and
    now you have 1st gear available.
    1st is very, very low, but will pull up mountains.
    Lukeb1961, Apr 14, 2012
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