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  1. #1

    My 1995 SL750 project

    Hey all! Been trolling around here for a couple days trying to get smart(er) on my latest project. Picked up a 1995 SL750 with about 50 hours on it for $250, knowing that they have knocked a cylinder out.

    Took a chance, figured for $250 it would be a good project anyway. This project is intended to be something to screw around with this summer. I'd like to build something reliable, but I don't see myself keeping the machine for more than a couple years. So I'm looking for advice somewhere above "just duct tape it and ride till she blows" but below "only a goober would re-install a used exhaust manifold." As far as my skill level, I'm brave (dumb) enough to do just about any job, and have most of the basics for tools. (No machining-type work/tools)

    So, as advertised, the PTO piston has a hole in it. Other cylinders appear to have no "wash" on them to speak of. So pretty obvious this was starving for fuel. (See pics, the PTO pic looks lighter than it actually is. Center is wet because of oil being dribbled in there during pulling the motor). Obviously I'm not JB welding the piston crown, so that's getting replaced. Planning to de-glaze/hone all 3 cylinders, and new rings all around. Is the scoring I'm seeing on this piston acceptable? It's light enough that I can feel it, but not deep enough to catch a finger nail. Do I need to address that? Anything I can do about it, or is it to the point of requiring replacement?

    As far as reeds, PTO and Mag were OK-ish, some chipping but still looked like they had some life in them. The center, one of the petals was pretty beat up, about a pencil sized hole in it. I have a couple sets of used reed blocks on the way, hoping I can make one good set. The question I have here (and probably should have asked before ordering used) is are used reeds a bad idea? Like on a scale of "You're good, don't worry about it" to "You're an idiot for even considering. And you should feel bad."

    Lastly, fueling. All three carbs are getting re-built with whatever parts come in the Watcon kit. I have a new triple output fuel pump en-route. I checked the "stuff" in the fuel tank, all appears to be clean and in order. Autocock is nowhere to be found, so it was either never there or removed. What do you guys think of the existing fuel line? It appears to be marine grade, but I have no idea if this is the stock stuff that should be replaced or if it appears to have been replaced already. I haven't checked to see a restrictor plug is in the return or not, but I couldn't find a solid answer on if this machine is supposed to have one, or if they are built into the carbs.

    I've read through the "Everything you need to know about the Fuji engine" and the "780 complete rebuild" posts (thank you guys, excellent posts). Anything else that's a must read?
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  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Welcome to the Hulk.

    Interesting first post.

    If you can catch a finger nail on damage to cyl, I would suggest having cyl bored and going oversize. If not, might be able to get away with just a hone job.

    I would not use "used" reeds. If you bought stock used petals and install them up-side down. there's a good chance they may break.

    Watcon is a good kit. Pretty sure John gives you the needle and seats too.

    If the fuel lines are hard and brittle or appear to be deteriorating replace them. You don't want an air leak.

    After you do the piston swap, do a leak down test to see if it's a crank seal gone bad that caused the PTO to burn down. Shouldn't matter because you'll need a new top end gasket set to do the piston replacement.

  3. #3
    Thanks for the reply.

    I forgot to mention, I planned on doing crank seals as well. With as long as this thing sat (I forgot to mention that too, this thing has been sitting since 2009) I figured the seals would be dead too. But still plan on doing a leakdown just to make sure I didn't flub anything.

    Got my first job on the ski done last night though, while I'm waiting for parts: The MFD is alive again, and shockingly everything seems to work!

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Crank seals is a good thing. You will become familiar with the engine then.

    TIP: make sure to periodically roll the crank over by hand as you tighten the engine case bolts in sequence. if you sense any binding of the crank at all, something is wrong and needs to be addressed. Don't just torque it and call it good. It should roll over really easily. Don't forget to pack marine grease between the 2 PTO crank seals.

  5. #5
    Well, I'm gonna burn in hell now: I put the base gaskets on upside down. The "built in" silicone on the gasket facing down with a skim coat of RTV on the top. According to the clymer manual that's backwards. Argh. Worth ripping the top-end off again to flip them around?

    The other thing that's a little off, the piston skirt clearance is within the "maximum wear" specs in all three holes, but the ring-gap at the top is about .002" beyond the max according to the chart that came with the WSM kit. (Measured .022") Is this a "throw it away and start again" issue? I assume the biggest issue would potentially be slightly lower compression?

    Other than that, things seem to be going back together reasonably well. Case seals are replaced and the bottom end is sealed back up. Carbs are cleaned and synced. (Thanks to John/Watcon for the kits)

    Got a start on the fuel pump/plumbing. I ended up purchasing some Tygon tubing from McMaster (MCM part 5552K25), but I don't like the way the stock worm clamps were biting into it. A #4 clamp would just deform before it got down to the 3/8" OD of the tube. I came across another post suggesting these vibration resistant clamps, so going to give them a whirl: https://www.mcmaster.com/catalog/126/339 Part number 52545K27. I went with the 11/32-13/32 size. I still need to make/get the proper tool, but I like them better already.

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  6. #6
    ripcuda's Avatar
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    Don't worry about the cylinder base gaskets. They will be fine.

    Did you replace all 3 pistons or just the bad one?

    How are you measuring piston to cylinder clearances? It can be a nit-picky process. I won't admit to just pushing the piston up and down in the cylinder and making sure it's not too loose and not too tight... and just sending it.

    Tygon is not a recommended fuel line choice. Like you've discovered, it compresses a lot and can make good clamping tricky. I would use regular automotive fuel hose over Tygon... and Marine grade proper fuel hoses (like the stock fuel lines) over automotive fuel hose.

    You running the oil pump? Might want to check your fuel selector valve too. I've replaced one this season already. They leak air into the fuel lines that feed the fuel pump. Needs to be air-tight from tank to pump (and to carbs).

    Cheers!

  7. #7
    Hey Rip, thanks for the input.

    I only replaced the bad one. I used the old piston to check all 3 holes, pushed it all the way to the bottom, so the skirt lines up with the bottom of the sleeve. Then started cramming feeler gauges in, parallel with the bore, center of the skirt, until I found one that I couldn't fit. I also checked by pushing the gauges in perpendicular to the bore, between the skirt and sleeve. I don't remember the measurement, but I couldn't get the "max wear" one in anywhere. I also checked the clearance for the new piston in the hole it was going in to, with the same result.

    As far as the tygon, I would tend to agree. It seems to soft for the task at hand. It seems like fuel line is like arguing religion, found plenty of posts saying that the "clear" tube like Tygon is fine, and plenty saying that the only real hose to use is marine. I can certainly understand the arguments for using marine grade. Since I already spent the $$ on the tube and clamps that I have, I ended up running with them. I look forward to all the "I told you so's" next year when I'm ripping it all out again.

    I took a look at the fuel selector. Tore it apart, cleaned, replaced the o-ring. At least with my clear tube I'll be able to see if there's air bubbles.

    As for the oil pump. As of now I plan on keeping it. I'm going to do the initial break in with 32:1 premix, figure that will give me a chance to make sure the oil pump is doing its job.

    Again, appreciate the input. My first PWC re-build, been fun so far.

    Engine's back in, so time to move on to the test fire!

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    You may get lucky, but I did not when i used Tygon for the fuel hoses. It's very soft and good for fuel pressure. It doesn't do well when under vacuum. Like pulling fuel from the fuel tank.

    If you find changing jets to larger ones doesn't seem to make a difference, swap over to reinforced fuel hose.

  9. #9

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    I thought RTV in a two stroke engine was a no no. I was always told to use a special sealant such as 3 Bond.

  10. #10
    Yeah, xlint, I don't put myself in the "lucky" category. So I assume I'll be replacing it eventually. Again, great advice, I'll keep an eye out for collapsing fuel lines. I was smart enough to use marine hose for the pulse line, does that count? =)

    Mocking, technically 3bond 1211 is an RTV as well. (http://www.suimportracing.com/images...-Tech-Data.pdf) The blue stuff from various vendors is not good, not fuel resistant. Various sources seemed to indicate that Permatex Ultra Grey is similar to 1211. I ended up using a fuel/oil resistant DAP product. (https://www.dap.com/products-project...ket-in-a-tube/) I'm no expert in the matter, obviously, but I was going under the assumption that as long as it was fuel resistant it will be fine. (I think I got too much of my step-dads "farm boy" training.)

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