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  1. #1

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    Modded 1992 SL650 Questions

    I picked this ski up a couple of years ago with a melted mag end piston (no surprise) from a guy I used to work with for $250 including a Bandit 1 place galvanized trailer. I really knew nothing about these machines but I figured that the trailer alone was worth it so I went ahead and bought it. Anyway, I replaced the pistons with a set of .020" Wisecos, replaced the stock fuel pump with a 3 output Mikuni, and put in a new set of Boyesen reeds. It initially ran quite well but despite my removing and thoroughly cleaning the crud out of the tank it began to clog the fuel filter every hour or so. I found a very nice (i.e. clean) tank on ebay so that problem has been laid to rest. Apparently it has had some mods done as my good friend who is a machinist with a lot of 2 stroke experience made it known to me that the jugs were already ported and the pistons that came out were also Wisecos. It also has a set of Ocean Pro SA's on it, the chokes removed, the oil injection removed and a primer kit installed as well what appears to me to be an aftermarket ride plate and intake grate. I also noticed it appears to have a 1993 type cooling hose set up. It might have an aftermarket impeller, if anyone can tell me what to look for I'll see if we can figure that out. It had been laid up for two years since then (new baby so no time for the machine) and we are hoping to take it on vacation with us at the end of this month so I've been working hard at getting it all straightened out. I removed the tank, emptied out the old fuel and replaced it with a fresh tank of 93 octane mixed at 40:1 with Polaris oil and the appropriate amount of Sta-Bil just for good measure. After pumping a bunch of old, nasty fuel out of the primer and into a can I got some fresh gas out of the hose, hooked the primer back up, and it fired right up. It seemed to run OK but when I'd rev it a little on the trailer, the RPMs wouldn't come down very quickly. I have about 15 years of experience with single cylinder dirt bike/ATV 2 strokes and to me it sounded like it was a touch lean. Once I put it in the water, I fired it up, let it warm up a bit and tried to take a nice easy cruise around to feel it out for any problems. When I'd roll into the gas to get it up on plane it would just be flat but not die, almost like it wasn't getting enough fuel so I gave the primer a half a pump to see if it would "pick up" at all but it just about stalled so I'm guessing it wasn't lean. I loaded it up, brought it home, and checked the "usual suspects" that I've found to be common problems from searching on this board. Here is what I've done so far:

    - Checked the fuel filter (new) - OK

    - Fuel filler cap/seal seem to be in good shape so hopefully no water got in the fuel

    - Checked all the fuel hoses - OK

    - Checked the fuel return for the restrictor - OK

    - Disassembled the fuel selector to check for debris/cracked O-rings - OK

    - Checked my fuel line routing from the 3 outlet pump to the carbs against the picture/diagram I found on this board - OK

    - Re-checked fuel pickup lines/strainers in tank - OK

    - Trimmed back plug wires 1/4" and reattached boots - OK

    - Checked compression [email protected] [email protected] [email protected] - OK

    - Checked spark plugs, they looked a little dark and will be replaced

    - Set all low and high speed adjustments on carbs to specs found in Clymer manual as well as on this site - they were all too far out by at least 1/2 turn

    None of the other stuff I did seemed to turn up anything or make any difference in the way the engine would free rev a bit on the trailer after I cracked the throttle until I adjusted the carbs. Now it seems to rev up and come right back down, but if all of the screws were too far out it should have been rich and not lean, right? If anyone has any input on this I'd really appreciate it. If the adjustments I made get the ski to run well enough for us to cruise around on it a little on vacation I'd be fine with that, then I can pull the carbs and rebuild them when we get back since they probably need it anyway. I've got a few more questions about some of the stuff that is on the ski and I took some pics so those of you who really know these machines can tell me just what I might have here:

    Quick pic of the whole ski:



    Does this look like a 1993 type cooling set up to everyone else?
    Is the flush fitting on the lower hose in the right place (I don't think it is so I haven't used it yet)?
    Should the temp sensor be where that 90* fitting is in the water outlet manifold and if so what how should I re-plumb that?



    Aftermarket intake grate? Any clue on brand?



    Aftermarket ride plate? Brand?



    This plug should go to the temp sensor, right?



    I'm going to put it back in the lake on Friday evening or Saturday morning to see if its running any better and if it is I'll spend a few hours trying to tune the carbs as per the great how-to I found on here. Sorry for such a big post but I figured I'd get it all out of the way in one shot. Thanks in advance for any help.

    John


  2. #2
    Moderator beerdart's Avatar
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    Welcome to the Hulk.

    I think you need to go thru the carbs and clean them. It looks like you have a 750 electrical box as the plug in the pic is for the MFD display. The cooling routing looks strange can you get more pics or a diagram?

  3. #3

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    Thanks beerdart, I'll snap some better pics of the cooling hose routing and the electrical box when I get home this evening. According to my service manual the colors of the wires going to that plug match the colors that go to the temp sensor. Also, if it makes any difference, there is the wiring going up under the handlebar pad for the buzzer so I assume that the buzzer is still under there. If that plug turns out to be for the temp sensor can I just short those two wires together to see if the buzzer goes off? When removing the carbs what are the chances of getting the carb gaskets off intact and re-usable? Should I just order a set of gaskets before I even bother taking them off? I've torn down plenty of dirtbike and ATV carbs but these are nothing like those are. Can these be disassembled without needing to replace all the gaskets on the carbs? Thanks and I'll get some pics with the real digital camera tonight, not just the cell phone pics.

    John

  4. #4

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    I wanted to get some pics with the real camera tonight but my wife had it and she wasn't getting home until after dark so I took some more with the cell phone:











    Hopefully these will help shed some more light on what I've got going on here. I was working on getting the trailer adjusted to fit the skis tonight since they were each on their own separate one before I bought the two place and when I was done I figured I'd hit the start button on the SL650. It fired immediately, no primer, no cranking, it just started right up. That alone is a big improvement over how it was before I adjusted the carbs and trimmed the plug wires. If there is any other pics anyone needs in order to help me figure out just what is going on here I'd be happy to snap some.

    Thanks Again!

    John

  5. #5
    Moderator beerdart's Avatar
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    The pics help your water routing looks good and the wire plug is most likely the temp sensor. Keep an eye on the cylinder temps and piston wash.

  6. #6

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    Thanks so much for the input beerdart. Does it also look like the flush kit is located in the right place? I'm going to keep an eye out for a temp sensor since it appears to be no longer available from Polaris. I'm optimistic that I'll have some positive results when I drop it in the lake Saturday morning.

    John

  7. #7
    Moderator beerdart's Avatar
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    You can flush it where in inlet line is coupled in the pic. For the first run leave the seat off and feel the cylinder temps with you hand. Good luck and take your time to make sure it is healthy.

  8. #8

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    OK, I've got a little insight into the problem now. I brought it down to the lake and ran it on the trailer in the water to see if it'd rev up at all. As soon as it starts to rev it bogs down. I watched the fuel filter while I was doing this and it is not only pretty much empty, the fuel is just barely trickling into it. I put the Mikuni 3 outlet pump on it about 4 or 5 years ago (when I first built it). Could that pump have gone bad already? I'm going to pull the fuel pick up out and have a look at it but all the hoses looked perfect when I put the new tank in. If there's a chance of it being the pump I'll order one today, we're leaving for vacation a week from today, I thought I had one more weekend to get it sorted but I don't.

    John
    Last edited by atc250r; 08-16-2008 at 03:23 PM.

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by atc250r View Post
    ...fuel filter while I was doing this and it is not only pretty much empty, the fuel is just barely trickling into it. I put the Mikuni 3 outlet pump on it about 4 or 5 years ago (when I first built it). Could that pump have gone bad already? ...
    Just to be sure, check compression for the PTO cylinder, and check that the pulse line to the fuel pump is good. Make sure it doesn't have a sag where fluids could accumulate inside the pulse line.

    Also check all the fuel lines leading to the fuel pump for air leaks, and check the fuel selector valve for air leaks.
    Last edited by K447; 08-17-2008 at 12:11 AM.

  10. #10
    la90043's Avatar
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    the fuel flows pretty much by gravity from the tank down to the fuel pump.

    the fuel pump pushes fuel up to the carbs from the fuel pump.

    pull out that fuel filter. check the fuel valve (petcock) for proper operation. though it can be in the "on" position it can be internally in the off position or just slightly. you can have a kinked or bent fuel line somewhere too between the pump and the fuel tank especially where they come out of the fuel tank. you can have an air leak somewhere that your system is sucking in air instead of fuel. make sure all hose clamps are tight and not eating through the hose.

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