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  1. #1

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    780 psi tiple pipes

    O.k guys trying to get my new project up and going so i thought i would fill ul in a little. Its going to start with 92 sl650 hull then to the the engine. a new lowerend with new seals and trued welded crank with hotrod rods (thanks to beerdart). the topend is going be freshly bored 72mm with new wiseco pistons. going to be using a single layer head gasket to bump up the compression a little. the electrical is going to be 785 coils/cdi/electrical (all from beerdarts project) and also upgrading the 92 650 hull with a mfd. and for the exhaust il be going with some psi triple pipes. going with some 44mm 785 carbs on the fuel side which i think iam going to attempt to run my new triple outlet fuel pump with the 38mm backs/crossovers and for the pump iam going to be running a stock 785 impleller 12/17 and spacer (with short driveshaft) with a slx ride plate.


  2. #2

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    ill fill in anything that i left off later and keep ul upadated. any thoughts and or suggestions will be greatly appreciated. especially on the fuel side. LOL. Iam sure ill have some questions il need answered in several areas of this project so keep ur eye out for me. LOL

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    What heads are you going to be using? Stock bore 780 heads on a 72mm (.75mm OS) will cause problems.

    You may have contact issues, and your compression will be higher because of the oversized pistons.

    Why are you trying to run a triple outlet fuel pump? (I hope it's the H.O. pentagon pump at least)

    I'll tell you right now, that 12/17 impeller is going to be too small for thet set up. Those pipes like to be run around 6900 RPM.

    I was turning about 7100 with a 15/20 and that same set up. Even Keddano's triple pipes 750 had a 14/19 on it....

  4. #4

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    well ive decided agianst using the triple fuel pump. iam just going to drill the reed spacer and add a pulse line.

  5. #5

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    o.k so what would be a good impeller to use? i was going with the 785 12/17 cause they run what is it around 140hp with triples so i fiugerd it should work out pretty good.

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by 450warrior View Post
    well ive decided agianst using the triple fuel pump. iam just going to drill the reed spacer and add a pulse line.
    I'll trade you my reed spacer that's tapped already for one that isn't....

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by 450warrior View Post
    o.k so what would be a good impeller to use? i was going with the 785 12/17 cause they run what is it around 140hp with triples so i fiugerd it should work out pretty good.
    785 turn almost 8000 RPM, you're looking to turn 6900-7000.

    That's where the PSI pipes make the most power.

  8. #8

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    sounds like a deal on the spacer pm sent.

    ul think i should try the stock 4 blade impeller or the 12/17 before getting something diff? or just ditch them both and try to get another? i dont mind buying the right one if someone can get me close on which one i need. i just aint got the cash to be buying several diff impellers.

  9. #9

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    and does anyone got any suggestions on were to start with jets? i think i got 97 44mm carbs.

  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    PM sent about the reed spacer.

    I'd start with the 15/20 first. If my tachometer was right, I was turning nearly 7300 RPM with that set up. You can always have the impeller rebent 1* up or down if need be.

    How good is that 12/17? You may be able to sell it to pay for the new one you need.

    As for jetting, look and see what Starflight was using on his project. Sounds like he was pretty close to being dialed in. (good starting point I suppose)

    And how about the heads? What are you doing with those?

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