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  1. #1

    Reviving the 1994 SL650

    edit - **Pictures in third post**

    Greets greenhulk
    I have browsed these forums for quite some time now, but only within the last week did I register . Woot!

    So, on with the tale of the sick. I purchased a 94 SL650 from a guy with no trailer for 150 bucks. It was "complete" but not running. The hull is in fantastic shape, but it is getting a paint job (pics to come ) because I like to make everything complicated -_- I am a Polaris fan and am pretty well informed on the history of their PWC. I also own a manual on the ski so I am ahead there as well Now on to the concern and questions.

    The PO took the ski and had it bored .6 over or some figure. The cylinders, when compared with one of my other stock ski jugs, are HUGE and quite obvious. The problem is that all the pistons have holes in them, or are chewed away a little bit on the sides (pics if needed?) . Not only that, I am mising the #1 cylinder jug (the one he gave me was stock...) so I have two huge jugs and one stock jug.

    I was told by the PO that his son's friend decided it wasn't running right, took a screwdriver to the carbs and 1 2 6, ended up with a ruined ski...I am thinking something else could have been out of wack as well though. So, the dilemma and questions:

    1) Due to my unique bore and lack of jug situation, would I be best just buying a different engine? I am concerned that, if something like oil pump failure occurred, my crank and GOK what else is effed.

    2) I dont trust mechanical parts. That is why I don't go on roller coasters. I would like to just bypass the oil injection and do like I do with my dirtbike chainsaw etc. Is this ever a bad idea?

    3) On the subject of what could have destroyed the engine, is a ECU problem a possibility? I took my box apart to get some wires out for removing the engine, and I noticed the ruber gasket between the two halfes was missing . How easy is it to KILL these boxes and how easy is it to FIX them ?

    4) Oh YES, what are good other choices for engine swaps into this ski? I have read about the 750 engines and their huge bonus, but is there any other popular swap? I like the 650 for its size and maneuverability (we own two) so I would love to keep it rather than buying a new ski.

    Sorry for all the text, I'd appreciate any input

  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Welcome to the Hulk

    See my signature links for lots of useful info, if you have not already.

    How long did this machine sit since it last ran?

    I suspect others will also advise you to do a proper rebuild on that engine. You need to be sure the crank is 100% good and that there is zero metal debris down there from the top end problems. Inspect intake reeds and crank seals too.

    You can run with different sized cylinders and pistons. Not a big deal, especially on the smaller HP engines. Each cylinder must be within spec for that bore size with proper clearances to the matching piston.

    Fuel system should be refreshed from end to end, with all hoses replaced including any inside the fuel tank. New fuel and oil filters too. If the inside of the fuel tank is not clean then clean it thoroughly.

    Also dis-assemble, clean and rebuild the carburetors.

    If you remove the oil pump and switch to premix you will burn oil at a higher rate. If the oil pump is a variable rate pump (with a control link between oil pump and carburetor throttle) then premixing will require rougly twice the oil consumption. Standard fuelil ratio for premix on Polaris is 40:1

    The Polaris oil pumps in general have a decent reputation for reliability and many oiling failures are caused by lack of inspection and non-maintenance of the oil uses and clamps. Install all new oil hoses with proper clamps, inspect the entire system, and your oiling system can provide reliable service. Less exhaust smoke and less oil expense too.

    The Polaris CDI ignition system for the blue Fuji engines is generally reliable and I would be surprised if a CDI failure caused engine damage. Water and corrosion inside the electrical box is not good. Clean or replace connections that show corrosion. Replace the seal. Inspect everything, make sure all the parts are in there and are properly mounted.

    Your 1994 hull has the modular 148mm jet pump, which was used from 1994 through 2004. If you upgrade to the 750 engine you will also need to install the matching 750 impeller.

  3. #3
    Thanks for the quick reply and I feel welcome Well the registration expired in 09, so I would guess the ski sat for close to three years

    Ahh I didn't realize I could get away with that much of a difference in cylinder size! But I'm sure it won't be to hard locating pistons for the jugs, I just am not sure the cost will be worth it...?

    How can I check and make sure my crank is good? The rod bearings all feel good (as in, no slop) but that's the extent of my crank checking currently.

    I am re-doing all my fuel system, new hoses, fuel filter, cleaning switch, pump etc. Carbs are getting taken apart and cleaned/replaced as necessary.

    My oil pump is not the variable one, so I think I just may go ahead and remove the injection system :/ I like the simpler setup ass well.

    When you say my jet pump is the modular one from 94-04, what do you mean? Is it bigger and better than the one in my 93? o_0 Something you didn't mention but now has me curious is, can the 750 engine run on the 650 ECU box?

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  4. #4

    Join Date
    Jun 2011
    Ypsilanti, Mi
    I would add the triple fuel pump and put some sponsons for better handling. Check the size of those larger jugs and pistons, they might be from a 750.

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