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  1. #1
    BBCaprice's Avatar
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    Hey Fuji guys- need advice

    My 780 finally gave it up. Cen piston was running to lean and burnt some of the edge off it. Middle of the piston was starting to dimple too. Anyway, I want to put a fresh top end on it (all 3). Might not need bored but was thinking .020 over to get to 795 cc. My questions are;
    Wiseco or WSM?
    Is it worth it to mill the heads? and by how much?
    What should final hone finish be?
    Dump oil inj or keep it. Randy once recommended not to get rid of it on the Fuji's.
    Thanks for any thoughts/info.


  2. #2
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    If you don't need to bore, is getting 16 more ccs worth the expense? All new pistons, machine work? I'd leave it standard myself.
    Beerdart can hook you up with some thinner than stock base gaskets, and if you split the 2 piece head gasket and use only one piece, that'll get ya between 150-160 psi compression that you can still run on pump gas. Those items will get you a little more punch.


    Oh yeah I almost forgot.... I honed with 320 grit, and used wsm pistons and all is well.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    If you don't have to bore, then don't. It leaves more room for future oversize pistons VS having to buy new cyls next time.

    Also, the heads should be opened up the size of the pistons. So, if you go 20 over pistons, technically the heads should go 20 over as well. You'll start to create a "shelf" that may interfere with the piston at TDC if you don't.

    Also, when you bore your cyls, you kinda lower the intake ports height a touch. This may actually decrease top end performance. (I doubt you'd ever notice it though)

    The manual recommends a fine grit finish, that's all it says.

    I'd run WSM over Wiseco. Closer tolerances and works just fine for a slightly cheaper price.

    I say dump the injection. It will smaoke a bit more, but you'll never have to worry about lack of oil again.

    Unless you let someone else fill up the fuel tank...

  4. #4
    johnsonmtz's Avatar
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    Quote Originally Posted by starflight View Post
    ....if you split the 2 piece head gasket and use only one piece, that'll get ya between 150-160 psi compression that you can still run on pump gas. Those items will get you a little more punch.
    No kidding? Hmmm I need to pull my heads and check my piston wash. I have new head gaskets to use when I put it back together. So I can just split the two piece gaskets and have a spare set to use if I need to remove the heads later.....AND boost compression at the same time? Sounds cool to me!

    KJ

  5. #5
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    Make that bad boy a 750,Still got that motor sitting here.

    Here's a guy parting a 780,if you want to go on the cheap.
    http://www.greenhulk.net/forums/showthread.php?t=97441

  6. #6
    BBCaprice's Avatar
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    Not worried about doing as cheap as possible just thought some extra cc's-more power.

  7. #7
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Quote Originally Posted by Keddano View Post
    Go the least amount of overbore you can.It will save room for doing more later if needed. max overbore won't gain that much performance differance.
    That's what I think also.

  8. #8
    BBCaprice's Avatar
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    Well after getting apart it will def need a bore-probably 1mm. Mag and PTO also got some weird looking wear patterns like the cyls are out of round. Dont know anybody to do this around here. Who would be good to send them to?

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    1mm, why so big?

    I had Sharpes Marine do mine.

    Randy from Watcon could do them.

  10. #10
    BBCaprice's Avatar
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    Yeah, dont need to go 1. .5mm will be enough. Talked to Jay (4strokepolaristech) gonna let him do them. Decided to ditch the oil inj since I'm already premixing the other boat. Plus the oil tank seems to leak from somewhere. Found the front 2 motor mounts were broke also- got a bid on fleabay for some. Probably need to check the pump alignment. Thinking about crank seals now-what do you think?

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