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  1. #1
    bowsniper's Avatar
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    Crankshaft sizes

    Could someone explain the differences between the 650,750,780,1010 1050 785 700.900,1200 cranks.

    650- basic fugi crank for 3 cylinder
    750-same as above-same rods different bore
    780-same as above- different bore and porting?
    785? (domestic-red ? or is it a fugi crank in a domestic case?)
    700-twin crank?
    900-twin?
    1050-?
    1010-?
    1200? (SLX and PRO-) The same crank?
    It's a little confusing. Thx

    Can any of these be Modded? like lightening the rotating mass on the counterweights? or shaving the weights into knives? and of course wearing ceramic bearings!


  2. #2
    thester71's Avatar
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    Quote Originally Posted by bowsniper View Post
    Could someone explain the differences between the 650,750,780,1010 1050 785 700.900,1200 cranks.

    650- basic fugi crank for 3 cylinder
    750-same as above-same rods different bore
    780-same as above- different bore and porting?
    785? (domestic-red ? or is it a fugi crank in a domestic case?)
    700-twin crank?
    900-twin?
    1050-?
    1010-?
    1200? (SLX and PRO-) The same crank?
    It's a little confusing. Thx

    Can any of these be Modded? like lightening the rotating mass on the counterweights? or shaving the weights into knives? and of course wearing ceramic bearings!
    The 785 is a fuji motor, crank and cases.

  3. #3
    Canadian Beaver Inspector jkindt's Avatar
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    Quote Originally Posted by thester71 View Post
    The 785 is a fuji motor, crank and cases.
    785 is a Fuji motor but has a longer stroke and longer rods. The cylinders are taller and have exhaust valves.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Arrow Polaris PWC engine sizes, engine families, bore and stroke

    Quote Originally Posted by bowsniper View Post
    Could someone explain the differences between the 650,750,780,1010 1050 785 700, 900,1200 cranks...
    All this info is in the service manuals, parts manuals, Polaris cross reference, Polaris PWC model chart, and elsewhere

    Note that in many cases the actual engine displacement is not exactly the same as the model code
    (Bore x Stroke)

    Fuji engines (painted blue, except Pro 785)
    650 (647cc) 3 cylinder (65mm x 65mm) SL650

    750 (744cc) same rods different bore (69.72mm x 65mm) SL750, SLT750

    780 (779cc) same rods different bore (71.3mm x 65mm) SL780, SLT780, SLX780 different exhaust manifold bolt pattern

    785 (779cc?) Fuji crank in a Fuji case (69.705mm x 68mm ) (750 size pistons, longer throw and rods, exhaust valves) Nikasil cylinder plating

    1010 (or any Fuji engine larger than above) - Heavily worked Fuji engine (bored, stroked, ported, massaged)


    Domestic engines (painted red, except MSX 140)
    700 (700cc, 701cc) twin cylinder crank (81mm x 68mm) - Hurricane, SL700, SLT700, carb'ed Virage (two-thirds of a 1050 engine)

    777 (aka 800) twin cylinder crank (84mm x 70mm) - carb'ed Octane & Virage i (fuel injected Virage twin) two thirds of a 1200 (1165cc) engine

    900 (889cc) three cylinder domestic SL900 (74.5mm x 68mm)

    1050 (1050cc) three cylinder domestic (81mm x 68mm) SL1050, SLX, SLTX, SLXH

    1200 (1165cc) - three cylinder domestic (84mm x 70mm)
    (Genesis and Genesis i/FFI, Virage TX and TXi, X-45, SLX and PRO 1200)

    1200 (1192cc) MSX 140 only (85mm x 70mm ) Nikasil cylinder plating

    1450 (or anything else above 1165/1192cc) bored, stroked, ported, massaged


    Weber 4-stroke two cylinder turbocharged, inter-cooled engine

    750cc MSX 110 and MSX 150

  5. #5
    Hayabusa's Avatar
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    Quote Originally Posted by bowsniper View Post
    Could someone explain the differences between the 650,750,780,1010 1050 785 700.900,1200 cranks.

    650- basic fugi crank for 3 cylinder
    750-same as above-same rods different bore
    780-same as above- different bore and porting?
    785? (domestic-red ? or is it a fugi crank in a domestic case?)
    700-twin crank?
    900-twin?
    1050-?
    1010-?
    1200? (SLX and PRO-) The same crank?
    It's a little confusing. Thx

    Can any of these be Modded? like lightening the rotating mass on the counterweights? or shaving the weights into knives? and of course wearing ceramic bearings!
    The 1050 crank has full circle webs (counterweights) which can reduce engine vibration. Some people use this crank instead of the stock one when building a modified 1200 engine.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Hayabusa View Post
    The 1050 crank has full circle webs (counterweights) which can reduce engine vibration.

    Some people use this crank instead of the stock one when building a modified 1200 engine.
    The full circle 700/1050 cranks need to be modified to create the 70mm stroke of the 1165cc engine - correct?

  7. #7
    bowsniper's Avatar
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    K-447 you amaze me! U can find everything and anything on these skis! Wow. All in order too. I see theres a few I didn't list.

    I thought the 785 pro cases were a little different inside, someone said they had work done(ported cases possibly) to them in some way. So that means you can put a 785 crank in a 750 case or a 650 or a 780? If there the same cases.


    Then why did jkindt use the bottom of a 785 case on his sleeper then? if it's no different than a 750 bottom case.?

    Well does a 750 case have 2 pulse line outlets on it? Like the pro has? No, I don't think so. Maybe thats the only difference? But thats done easy enough.

    So that also means you could build a 785 motor with 750 cases then, and just use the jugs from a 785 then and the longer stroke crank. correct?

  8. #8
    thester71's Avatar
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    785 cases have different porting than the 750, the 785 crank has a larger stroke, so I dont think it would rotate inside a 750 case, that is just a guess though,I should have tried my rebuilt 785 crank in my 750 cases before i installed it.

  9. #9
    bowsniper's Avatar
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    That would be interesting to find out if that can be done. Maybe someone has already.

    Well after sanding the ruts out of the rods path in these cases, I could go with even longer rods now, The center rod took out a few thous at least where the rods spun n hit. . Lots of clearence now!

    Come to think of it, that wouldnt work, it would throw the port timing off.

  10. #10
    Hayabusa's Avatar
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    Quote Originally Posted by K447 View Post
    The full circle 700/1050 cranks need to be modified to create the 70mm stroke of the 1165cc engine - correct?
    You are correct, it's not a "drop in" type of mod. The stroke does have to be changed. Another advantage to using a 1050 full circle crank is that it stuffs the cases so static compression is raised.

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