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  1. #1
    NIXON'S BACK!! cincygpr's Avatar
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    New Problem -- GP1200R Poor Acceleration/Speed

    Okay, after putting the GPR back on the lake this morning, I did a few speed runs... 64.1MPH (GPS), 63.5MPH, 64.1MPH. The problem is... is that on the last speed run, it hit 64.1, but then the engine immediately bogged down and would not run any faster than 30MPH. I managed to make it back to the launch point, and when I turned it off and fired it again, it would fire and idle fine... but again, on takeoff, it would bog down and not run more than 10MPH, sporadically speeding up to 30, but then back down to 20 or 10.

    I recently installed a d-plate and 1000 Ohm resistor, which cleared up the idle problems and *I think* gained a bit of speed.

    Any suggestions? I was thinking it was the carbs, or something associated with them. I don't think it is a powervalve issue due to the WaveEaters.

    Help!!


  2. #2

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    Start by....

    Checking your reeds, PV's(I know that you have waveeaters by make sure they didn't break),compression test, your fuel slector on/off/res. Start with those. If your fuel pick up still has the flap door your going to want to take it out too.
    Good Luck, TCR

  3. #3
    NIXON'S BACK!! cincygpr's Avatar
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    Gas Valves?

    Thanks TCR! Shortly after posting the thread, I took the ski up to a reputatable dealer (on sy34010's recommendation), who was very helpful with at the very least diagnosing the problem...

    Compression across the cylinders was 110psi in #1 and 120psi in #'s 2 and 3. He said that 120psi is normal for an engine with a little bit of wear and tear, but #1 is a little bit of concern... the engine bogs down and cuts out as soon as you start to accelerate from idle, so he believes it to be a busted PV in #1. The only odd bit about it is that there's no metallic pinging from the engine when the throttle is blipped, so maybe the PV is just not opening fully, rather than completely dropped into the cylinder.

    I'm going to take the valves apart when I get a chance. I have no idea what i'm going to find, but i'll probably take the head off as well to get a peek of the cylinder and see if there's damage.

    I've been thinking about switching to the RIVA gas-operated valves rather than going with the billet RIVA valves that supposedly don't fail. Any input there?

  4. #4
    WE DONT DIAL 911 RDH's Avatar
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    if your willing to spend the money get the gas valves..

    take the head off and check everything, only takes a little while..

    mine bogs sometimes also but i ride for a second and it gets barked out,, it happens after speed runs where im loading the motor with fuel then off throttle....

    im suprised #3 isnt a little lower than #2... #3 dome on stock head is .5cc smaller

  5. #5
    Quote Originally Posted by cincygpr View Post

    Any suggestions? I was thinking it was the carbs, or something associated with them. I don't think it is a powervalve issue due to the WaveEaters.

    Help!!
    Mine behaved very similar to this when the PV servo motor went out... So perhaps your pvs are in fact fine with the clips in place, but the motor that controls them is the issue. Goodluck, let us know what you find out.

  6. #6
    mrbtd's Avatar
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    You can open your valves all the way and disconnect the PV motor. It will run like crap on the bottom but you will see if the top end is there.

    You can check the reeds by feathering the throttle - if you can build power by feathering it its a good indication you have a problem with the reeds. It will never be 100% but it wont fall on its face.

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