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  1. #1

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    Tear down: '94 SL750

    I decided to get started tearing down the other SL I got a few weeks ago. It's the one that cranks over, and ran very briefly on ether. Today's task was to remove the fuel tank and begin sorting out the fuel system. I figured out how to remove the oil tank, then pulled all the bolts/fittings for the fuel tank. As expected, the fuel hose inside the tank was mostly disintegrated. The bonus though was that there was enough water in the tank to grow some sort of green algae. I'm sure glad I got the tank out! I tried pressure washing it out, but just couldn't get a good angle to hit the gunk. So, I went manual: dumped a bunch of gravel in the tank, then a couple gallons of soapy water and sloshed it around until everything was clean again. Rinsed it out a coupe times and it looks MUCH better in there. I took some pics of the gunk, I'll post a link below.

    The two fittings I found inside: I assume the long skinny one is the fuel pickup, but I'm not sure what the fatter white plastic one is. I'm guessing it's something to do with the vent system, but not sure. Can anyone help me out on that?
    Thanks!
    https://photos.app.goo.gl/QJ7MkfG4J3bm8sBx7

  2. #2
    johnsonmtz's Avatar
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    Long skinny one is the main fuel pickup. Not sure what the white plastic one is but might be some other kind of pickup. Usually the main pickup sets about 1" or so off the bottom of the tank and the other one is the reserve which is pretty much on the bottom of the tank.

    There is one vent on the tank and that is external. It's a plastic disc about 3/4" diameter and is a one way check valve designed to only let air in as fuel is drawn out.


  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Spot on ^^^^^^^

    Should have 2 brass fittings with screens on them. One that runs to the bottom and the second one that sits a little above the bottom as mentioned above.

    Shouldn't be any plastic in there.

    Please post a pic of the part for us to see.

    Make sure to replace the whole fuel system if you plan on getting any reliability from that machine. New fuel lines, consider a new shut off valve, rebuild the carbs with genuine Mikuni carb rebuild kits. Install the restrictor in the return fuel hose, etc.....

    NOTE: Before buying/doing any of that ^^^^, I would first do a compression test and leak down test to see if the engine will be up to the task first.

  4. #4

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    The plastic part is in the pics I linked above. I'm pretty confident no one has been inside the tank since new, so I'm fairly certain it belongs in there.
    As for the rest, compression is good (118-118-115), and the entire fuel system will be replaced or rebuilt as appropriate. The problem seems to be in finding fuel lines with the USCG rating, at something approaching reasonable prices. Click image for larger version. 

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  5. #5
    Click avatar for tech links/info K447's Avatar
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    For fuel hose installed inside the fuel tank, the fuel hose should be rated for immersion in gasoline. Immersion rated fuel hose can be harder to source than ‘regular’ fuel hose.

    Regular fuel hose that is not rated for immersion may react poorly to having liquid gasoline in continuous contact with the outer layers of the hose material, which normally would be exposed to air and ventilation.

  6. #6

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    Yup. SAE 30R10 rating. So far, I'm looking at $35/ft....
    I've been talking with Saint-Gobain (the makers of "Tygon" branded tubing. So far their F-404-A or LP-1200 are good for immersion, but not rated for marine use. I'm certain the F-404a is the OEM tubing in the tank. LP-1600 is rated B-1, but trying to find a supplier is difficult.

  7. #7
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by skills4lou View Post
    Yup. SAE 30R10 rating. So far, I'm looking at $35/ft....

    I've been talking with Saint-Gobain (the makers of "Tygon" branded tubing. So far their F-404-A or LP-1200 are good for immersion, but not rated for marine use. I'm certain the F-404a is the OEM tubing in the tank.

    LP-1600 is rated B-1, but trying to find a supplier is difficult.
    I think the marine rating would be for fuel hose that is installed outside the fuel tank.

    I do not know if there is such a thing as immersion rated marine grade fuel hose

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    I have never seen one of those plastic pick ups.

    That blackish looking one is what I've always seen. It's really brass once cleaned up.

    I wonder if you can or would want to swap over to the newer style fuel pick up. It eliminates the plastic retaining ring on top of the fuel tank, eliminates those fuel lines immersed in fuel, and also eliminates the old style fuel float.

    You'd need the new style fuel pick up tube and fuel tank. Then just wire in the fuel sender wires.

  9. #9

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    Well, I took some more time today to tinker with the machine. I looked through the wire diagram and figured out that the fried wire (and I mean melted off insulation the entire length of the loom) at one point had black insulation, meaning it's a ground. The conductors are still there, just no insulation. I was going to pull the stator cover off and see about replacing the wire, but I think I may have a better solution to just get it running. Looking at the diagram it's just grounded to the stator housing, and then back to a ground in the waterproof box. So, I added another ground wire between the two points. We'll see how that goes, but the Ohm meter shows a good connection between those two nodes.
    Next up was to re-install the fuel and oil tanks. That went together pretty well, just had to remember how to fish the fuel tank sending unit back in place. Then I pulled the carbs (OK, it was an hour process getting those nuts off working blind). Anyway, carbs are off and I disassembled one just to see. Thankfully this one is quite clean inside, no gummed up junk or corrosion. SO, I'll need to get some carb kits. Does anyone have a source for kits that are less than $45/ea? MIKUNI kits, not the cheap chinese garbage ones. I learned that lesson many moons ago with a V4 Honda that made these SBN carbs look like childs play.

    Regarding the fuel hose, I found a part number for 10' of it at Napa that is immersion rated and was $16. They had to order it in, but it should be here sometime this next week. Does anyone have the measurements for the hoses so I get the pickup the right distance off the bottom?
    I've also found that the plastic part is apparently part of the vent system, and Polaris had an update kit to eliminate that. And, it turns out the part # was still available via fleabay for the updates, so that's now on order.

  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Nope, no other places I know of for the kits to be cheaper.

    What I would recommend is John Zigler at Rock County or Watcon (he bought Watcon a few years ago) for the rebuild kits. He has a kit that includes just the parts you need and it includes the needles and seats with his. Otherwise you need 3 Mikuni rebuild kits plus 3 needles and seats as well

    Can't help you on the hose length. What i would do is keep the main pick up about 1 1/2" from the bottom of the tank. That should leave you a decent amount of fuel as a reserve.

    So the plastic part was a spring loaded check valve for the vent system? Makes sense

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