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    Re: GT 550 Race Bike update. A cry for help

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    Posted by H2RICK on 3/17/2001, 9:25 am , in reply to "GT 550 Race Bike update. A cry for help"


    Is the engine thoroughly warmed up when you're trying your "alley test" ??
    Air cleaner(s)/air box on or off ?? Sounds like weak spark on LH cylinder at idle so no combustion thus wet plug. Check all electrical connections for that cylinder through entire circuit and clean all places where wires are joined i.e. bullet connectors, ring terminals, etc. Maybe bad plug cap ?? Try a new one. You can get NGK replacements from your dealer usually. Do you have a Champion firing indicator to check if you're actually getting spark on that cylinder at idle ?? If not, warm bike up, shut off, pull plug cap on LH cyl, put NEW CORRECTLY GAPPED IDENTICAL "test" plug in cap and ground plug somewhere. Start bike, watch "test" plug for spark. This will tell the tale. Rev up a little. Spark now ?? If no spark at idle but spark at higher revs, start looking for that bad electrical connection or corrosion somewhere in the circuit for that cylinder.
    If you DO have spark in "test" plug at idle, then install test plug in cylinder instead of what you currently have in there. Start up and see if cylinder now is firing. If so, problem was plug. If not, then problem is mixture OR compression JUST in that cylinder.
    Re: tach. I don't believe that 12,000 RPM reading either....maybe 8,500 or 9,000 max for your engine but YOU SHOULDN'T RUN IT AT HIGH SPEED UNTIL IT'S BROKEN IN, ANYWAY....but you already knew that, right ??
    Re: jetting. Sounds OK for "mild" porting but you have many happy hours of testing ahead of you with lots of plug checks too. Carry spare plugs and plug wrench in pocket at ALL times. You will need them.
    Depending on design of pipes, they may be built so that the bike "comes on the pipe" at about 5,000 which is VERY different from stock setup, which starts to pull at about 3,000 - 3,200. The pipes you have may be designed to run most efficiently in a fairly narrow band which is common for "race" chambers, as opposed to "street" chambers. "Race" pipes typically have a range of about
    1,000 to 1,500 RPM and God help you if you let the engine out of that range.
    Engine will "fall flat on its face" if you do. Start getting used to "rowing" on shifter lever while riding to keep engine in power band IF you have "race" chambers.
    Get some kind of accurate tach setup quickly so you can be sure of engine speed. Keep riding bike around to get rings seated nicely. Back off on premix as rings seat. Buy plugs by the box as you will need them.
    You MAY want to go back to 7 range plugs UNTIL engine is broken in BUT NO high speed stuff with 7 range plugs...slow/medium engine speeds only.
    Let us know what happens.


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