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  1. #1
    Mongoose's Avatar
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    800 powervalve project-Some questions?

    Hi,
    I have just gone back to old school -Again!- im sticking here this time though!
    Bought a basket case waveblaster 800-don't think they were ever sold in the US, but its basically a 800 powervalve engine and 144 pump in a small hull.
    It's going to be a major project-carbon strenghtning and some panels, complete respray in and out etc, and I will take some pics of the build and post them on here.
    Anyway barrels are shot, carbs are shot and the whole engine is in about 4 boxes!
    Not going really radical with the new engine, as it's going to be used in the surf.
    Should I rebuild the carbs to oem specs and stick with the oem airbox, or is it worth rebuilding to the same specs as we used to with the 1200r, do away with the accel pump and use aftermarket flame arrestors?
    Ive got a spare 3 degree keyway-is it worth using on this engine?
    Apart from a slight decking of the oem head to tidy it up and changing to premix, that,s as far as I planning to go with the motor.
    Thanks


  2. #2
    Mongoose's Avatar
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    Anybody have any input????

  3. #3
    dghal's Avatar
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    I don't ride surf,, but it sounds like it will be a sweet project,,

    Post progress if you will

  4. #4
    cfgp927's Avatar
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    A slight bump in compression is helpful to the 66E motors. To really see any major gains you must run aftermarket exhaust or go Big Bore (or both). The 3 deg keyway will probably not gain you much. I don't recall if it advances the timing, or retards it. Stay away from it if it advances the timing (jmo). The stock CDI timing curve is fairly agressive and doesn't need any more advance on the top end. As for carbs, I have done away with the stock airbox on all my machines and gone with aftermarket f/a's. You'll definitely have to re-jet. If you have the money buy some Novi's from Tim....you won't be disappointed. Hope this helps. Any other questions....don't hesitate to drop me a line.
    Mike

  5. #5
    Mongoose's Avatar
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    Quote Originally Posted by cfgp927 View Post
    A slight bump in compression is helpful to the 66E motors. To really see any major gains you must run aftermarket exhaust or go Big Bore (or both). The 3 deg keyway will probably not gain you much. I don't recall if it advances the timing, or retards it. Stay away from it if it advances the timing (jmo). The stock CDI timing curve is fairly agressive and doesn't need any more advance on the top end. As for carbs, I have done away with the stock airbox on all my machines and gone with aftermarket f/a's. You'll definitely have to re-jet. If you have the money buy some Novi's from Tim....you won't be disappointed. Hope this helps. Any other questions....don't hesitate to drop me a line.
    Mike
    Thanks Mike,
    will drop you a line as and when!
    Thanks for the timing tip-the keyway does advance it, so I wont fit that!
    what's the 'neptune' pipe on the GroupK big bore ski?

  6. #6
    cfgp927's Avatar
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    It's a single pipe from a sea-doo xp800 with a custom manifold to fit my GKBB 927. Right now it's hanging on the wall, as I'm test fitting a new rear chamber from a gp12r and a front chamber from a gp800. I WANT TWIN PIPES, and I'm gonna find a way to have them (the key for me is I don't want to cut and weld them to get them to fit)

  7. #7
    Mongoose's Avatar
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    Quote Originally Posted by cfgp927 View Post
    It's a single pipe from a sea-doo xp800 with a custom manifold to fit my GKBB 927. Right now it's hanging on the wall, as I'm test fitting a new rear chamber from a gp12r and a front chamber from a gp800. I WANT TWIN PIPES, and I'm gonna find a way to have them (the key for me is I don't want to cut and weld them to get them to fit)
    Is there a decent power bump with the neptune system?
    Im looking for the opposite to you!
    A pipe that will give a bit more hp, but something totally reliable for the ocean-like the Pro-tec pipe for the 760 (Hence my question about going down the 760 route).
    Is the 'neptune system available to everyone, and if so where from?
    If not, and you decide to move on, can I have first refusal Mike?
    Thanks

  8. #8

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    if you have to rebuild the motor use the 1300r cylinders, r&d or riva heads. use 1300r stock gasket. cut one side. you can use all the other stock parts and you will go from a 80mm (785cc)to 84mm (850cc) with all stock parts.

    or do what Mike said Big bore 86mm with pipes.

  9. #9
    cfgp927's Avatar
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    Because of the limited space in the c/f hull, I needed to adapt a chamber from a Seadoo pipe. I wanted a FPP spec 1 or 2 chamber, but didn't want to pay the premium price tag associated with even the used ones. I found a couple of Neptunes (2nd best pipe, according to my research) quite reasonable, so that's what I bought. The pipe might be good for a few hp, but the big benefit was weight savings over the stock 66E pipe. Yamaha did a great job designing the exhaust of the 66E, you really have to go to individual chambers to get a big HP increase. The weight of the stock pipe is ridiculous. If I ever decide to sell what I've got I'll let you know. In the meantime you could do the same thing by making a manifold and adapting a chamber of your choice.
    Mike

  10. #10
    Randy11023's Avatar
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    I am doing a project for my gp800 this winter also. I had one cylinder go bad on me but I fix it to get me by still winter. I just replace the rings and put I used piston in it and buffed and sanded a little the cylinder to get me by till the season end. US chrome supposes to and a warranty one this cylinder till oct so I and going to send it in get it replated.

    Anyways I looking to get more power out of it I not too much in the high speeds with since it my spear for friends and family. I just want more arm pulling out of it like my gp1200. I’m sure it really easy since I done alot of work on dirt bikes. I fig just a compression upgrade and bigger pump would do it. But you have any other tips??

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