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Thread: Help, engine running rough, weird noise

  1. #1
    Junior Member
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    Apr 2007
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    Exclamation Help, engine running rough, weird noise

    Well first the good news, it actually started!
    Prelude: Bike (2000 CBR 600 F4) was totalled by previous owner, bought it to rebuild. First time attempting to start it coolant and oil mixed, turned out heads were split open. Put in replacement head from a 2001 F4i after adapting it for the F4. New headgasket, checked valve clearances, checked cam timing, reinstalled everything. Fresh oil, fresh coolant, fresh gas.

    Here's what happened. I hooked up the gas tank today, triple checked fluids, and decided to give it a chance at starting. Took forever to start, I assume due to the fuel pump filling the carbs or something. Leading up to that it was making some weird plopping noises, almost like when a hose is under vacuum and you pop it off real quick, like a suction cup or something. It seems directly connected to the ignition because I unplugged the coil wires and the sound completely went away. Once it started it ran really rough making that same plopping noise, just much faster, it idled for a second at 1000rpm, then slowly dropped off until it died. By then my battery was dead from cranking over so much, so I pulled it and plugged it into the charger. I pulled the spark plugs real quick and they've got a lot of gas on them. No gas or oil or anything was coming out the exhaust ports (headers not on the engine) though. So right now I'm tired and stumped.

    Why did it take so long to start?
    What is that noise and should I be worried?
    What's with all the gas on the spark plugs?

    Thanks in advance if anyone can shed some light on this!

  2. #2
    Member txrc51fatboy's Avatar
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    Re: Help, engine running rough, weird noise

    Why did it take so long to start?
    takes awhile for carbs to prime with fuel, make sure fuel pump is working properly and no fuel lines are pinched


    What is that noise and should I be worried?
    popping noise could be emissions system introducing to much oxy into exhaust


    What's with all the gas on the spark plugs?
    flooded or running fuel rich, make sure carbs are propperly jetted and working good.

    do you have power commander or any other A/F adjuster installed on bike?
    stock ECU maybe bad
    04 RC51

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