aussiexjrridersclub – Yahoo! Groups

  • idleidol

    Jan 21, 2002

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    Well there ya go then, FJ1200 manifolds etc on
    the dyno (Winpep dynojet).<br>I just fitted fj1200
    manifolds, advanced the timing and drilled a few holes in
    the airbox.<br>The exhaust is standard but has had
    the 50mm centres drilled out and the baffle tube
    removed. <br>The airbox entry hole was opened up to match
    the filter but the bike still wanted more
    air.<br>Another hole on the opposite side of 30mm diameter and
    made up a foam seal to suit on the inside of the
    airbox.<br>Started with 112.5 main jets but they were a little lean.
    Ended up with 116 mains.<br>Horsepower was 121 BHP max
    at just under 9000 rpm. Another earlier run saw 124
    hp in another configuration but the mid range was
    crap.<br>I hadnt done the cam timing as Yamaha Australia
    took all day to fax the cam specs but we measured the
    cams anyway for reference. Later we had the specs and
    found the inlet to be fine but the exhaust about 4
    degrees out. I’ll get onto this later as it might help
    fatten up a bit of a flat area between 4 and 6000
    rpm.<br>The graph looks good and when I get a 4in1 pipe, I’ll
    do it all again.<br>From 6000rpm to red line was
    over 100 BHP and the torque graph was pretty much flat
    from about 3500 to 8500 with a peak of 85 ft/lb at
    6500rpm.<br>Best power range would be from just over 5000 rpm
    where the graph gets real steep to 9000rpm.<br>Yamaha
    quote 106 hp in standard form, dunno if this is genuine
    BHP or japanese hp. Probably at the crankshaft anyway
    which would mean under 100 hp at the back wheel.<br>The
    increase to 121 BHP at the back wheel when corrected to
    crankshaft horsepower indicates an increase of about
    25-30%.<br>The torque figure was disapointing given that Yamaha
    quote 100 ft/lb standard. Somehow I doubt their
    figure.<br>Next week we will run a standard but run in bike as a
    benchmark.<br>Indicated top speed in 4th gear was 140mph.<br>(I have an
    18 tooth front sprocket).<br>Now here’s some really
    good news, this mod helps fuel economy too. I found on
    the weekend that with my wife and luggage, just
    cruising at 100-120 kph with some fun blasts occasionally,
    it was getting about 18 kilometres per litre or in
    another way, 5.55 litres per 100 kilometres.<br>For the
    Poms, that is about 51 miles per gallon fully loaded
    with a 90kg driver and 63kg passenger and maybe 20kg
    of crap.