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  1. #1

    SL750 Project - Could Use Some Help!

    Kinda new here, been reading everyone's posts for about a year now but haven't done much posting myself.

    I just picked up a 1993 SL 750 from a guy who was giving it away in Columbus, OH...he said he just never had the time to work on the project and he said he needed to get it out of his garage. He told me the 2 main things that he knew were wrong with it were that it had low compression in all 3 cylinders and didn't have a spark. Cosmetically, though, this thing looks amazing. I'll try and post pics when I can.

    Soooo, to start, I bought 3 piston rebuild kits (just to be safe), I got 2 cylinders in good shape, and I got a new stator (all of this because I couldn't pass up the deals I got!). In addition, I got 3 new diaphragms for the carbs. I'm also going to be moving to the triple outlet fuel pump which I also just received in the mail.

    After getting about 2 feet of snow about a week and a half ago, I finally got a chance to get outside and open up the cylinders and see what was going on. I first ran a compression test and found that the rear cylinder gave me a reading of 122, the middle was 85, and the front was 90.

    Upon opening the cylinders, I first noticed that the rear cylinder looked pretty normal (compared to some of the pics I've seen on here). The first 2 pics show the rear cylinder and are labeled Rear 1 and Rear 2 respectively.

    The middle cylinder was a different story. When I opened this one up, I noticed that the piston was bone dry, in the up position, and looked completely seized. the next two pics show the middle cylinder and are labeled Middle 1 and Middle 2 respectively.

    I opened the front cylinder and didn't really know what to think of this one. It fired at only 90 PSI but didn't look TOO bad. The last pic shows the front cylinder and is labeled Front 1.

    Can anyone offer up any insight on what they may think of the cylinders/pistons and/or the project in general?

    Thanks in advance!
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  2. #2
    Moderator beerdart's Avatar
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    They don't look to bad. It looks like some water intrusion. Pull the cylinders and have a look at the crank and check crank index.

  3. #3
    gorilla03's Avatar
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    Quote Originally Posted by beerdart View Post
    They don't look to bad. It looks like some water intrusion. Pull the cylinders and have a look at the crank and check crank index.
    +1

    122 for compression is normal...like beerdart said might as well inspect the crank for damage...The last time i checked my compression was 125psi on all cylinders....if you do pull the cylinders, could you get some pictures of the sides of the pistons?

    how do the cylinder heads look???

  4. #4
    Oops, took some pics of the cylinder heads but forgot to post them!

    Here they are and I labeled them in the pics so they'd be easier for me when I was looking back through my camera.

    So how would I go about checking the crank index and what is the easiest to pull the cylinders out for future reference/
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  5. #5
    gorilla03's Avatar
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    ther is a article on checking crank index in the tech section

  6. #6
    What do you think of the heads based on what you see in the pics?

  7. #7
    Wankel till I die!! jonjonwells's Avatar
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    Congrats on the ski, it was extremely clean when I looked at it a while back.

    All in all, the pistons/heads look great. You could probably get away with re-ringing them. I would definately go ahead and check the crank as Beerdart stated. It is well worth the gasket kit to know that it is fine. While the jugs are off, go ahead and inspect the piston heads as well. Look for any damage and out of spec bearings.

    Check out the post by Beerdart for Crank Index...
    http://greenhulk.net/forums/showthre...t=51271&page=3

  8. #8
    Moderator beerdart's Avatar
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    A quick way to check index is with one piston at TDC the other two should measure the same from the top of the cylinder down.

  9. #9
    If it looks like I have water intrusion, is there a chance that the crank could be rusted as well? I really need to get down to that and check it out huh?

  10. #10
    seaobin's Avatar
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    Check the index first, before you tear it apart. Once you know either way, pull the jugs and visually check the bearings. Spin the crank. If you feel, see or hear anything other than a clean, smooth witha slight liquid moving sound, get the crank rebuilt

    $350 beat the crap out of hand paddling back a mile to the dock.

    Good luck

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