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  1. #11
    steve45's Avatar
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    I can guarantee that there is trash in the bottom. At the very least, turn it upside down and flush it out very thoroughly with a pneumatic solvent sprayer.

    If it hasn't been apart in a while, best to tear it down and replace the crank seals.


  2. #12
    Happily Self-Employed WFO's Avatar
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    Quote Originally Posted by Shadyraro View Post
    Iím not sure if itís sleeved or not, how can you tell?
    Also do you think the head is repairable? It has quite a bit of pitting on it.
    Now Iím wondering if I need to pull the motor to check the crank, it seemed to turn freely by hand.
    like Steve says, best to freshen up the bottom with at least seals and clean bearings. Personally with that much debris running thru that crank bearing id get it rebuilt, but I run a shop so it has to be done correctly.

    sleeves will be pressed into the bore, so you should see or feel in the transfer port or exh port for an extra step then you have sleeves. normal i can tell by the top of the cyl but yours are so filthy it hard to say by your pics... its an extra 1/4" or so "ring" around the bore that's different material and color from the rest of the top of the cyl.
    (I hope that makes since... that was harder to type out and explain that i thought it would be LOL)


  3. #13

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    GP1300 stuffed piston

    Thanks WFO, looks like an engine removal is on the cards. I took a couple more pics of the cylinders that might help to view the sleeve.
    I got quoted 5k for a full engine rebuild in Australia which is a lot more than I paid for the ski. I donít know if thatís a good price but Iím not willing to spend that much on it.
    I was going to do the top end myself as the rods and crank looked good, but now Iím second guessing myself about the bottom end.
    If the cylinder and head are unrepairable then that makes things more difficult, as a 3 piston and top end gasket kit are quite reasonably priced here.
    Click image for larger version. 

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  4. #14

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    Click image for larger version. 

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  5. #15
    steve45's Avatar
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    I don't know what the conversion factor from US dollars to OZ dollars is, but $5K is awfully high. Many shops here won't even work on 2-strokes anymore, so you have to do your own.

    I say do it yourself, if you can. Get a service manual first and see what's involved. That first picture you posted didn't show that gouge from the piston ring, or at least I couldn't see it. Yes, you'll need to replace it. Don't know what the used parts market is like down under. You can probably find a cylinder and head on US Ebay.

    As for the crank, I'd try cleaning it with solvent. Flush it out thoroughly, then do it some more. If you hear or feel any roughness in the bearings at all, send it in for a rebuild. Make certain that the crankcase is absolutely clean, as well.

    WFO is right in suggesting a crank rebuild, but he is doing it for a customer and he has to guarantee it. Getting a crank rebuilt really isn't that expensive, either.

    I use YamaBond when putting the crankcase halves and cylinders together, then pressure test to about 8 PSI.
    Last edited by steve45; 10-27-2021 at 07:36 AM. Reason: Cylinder replacement

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  7. #16
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    Those are definitely nikasil cylinders. Also...1 and 3 look very lean, I would check and clean the fuel injectors also. Cylinder 2 could also possibly be a lean failure, its hard to tell. Ive seen several pistons that were busted and looked like the ring spun, but ended up being run very lean and cooking the exhaust side off the piston. Like I said though...hard to tell from a pic. As others have said, tear down the bottom end also to freshen up the seals if nothing else, but that crank will have lots of debris in it for sure.

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  9. #17
    butterbean_29512's Avatar
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    Looked back and saw your spark plug thread, and now the failure makes a little more sense. The #2 piston almost certainly failed due to water ingress. I've got a 1200r I'm working on now, and the rear cylinder failed due to water ingress. It also hydrolocked the cylinder and knocked the crank out of phase. The cause of ingress on the one I'm working on was excessive corrosion that completely ate the anodes out of it. Corrosion punched through the cylinder wall and bam! Took it out. Yours looks to be running a good while with a small leak. Check the head gasket for a leak....if no apparent leak then examine the cylinder(s) closely for corrosion. Your anodes are a good indicator of corrosion. If they're ate up it's a good bet you'll have cylinder damage. I didn't see any anodes. Are they under the cylinder head cover?

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  11. #18

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    Quote Originally Posted by steve45 View Post
    I don't know what the conversion factor from US dollars to OZ dollars is, but $5K is awfully high. Many shops here won't even work on 2-strokes anymore, so you have to do your own.

    I say do it yourself, if you can. Get a service manual first and see what's involved. That first picture you posted didn't show that gouge from the piston ring, or at least I couldn't see it. Yes, you'll need to replace it. Don't know what the used parts market is like down under. You can probably find a cylinder and head on US Ebay.

    As for the crank, I'd try cleaning it with solvent. Flush it out thoroughly, then do it some more. If you hear or feel any roughness in the bearings at all, send it in for a rebuild. Make certain that the crankcase is absolutely clean, as well.

    WFO is right in suggesting a crank rebuild, but he is doing it for a customer and he has to guarantee it. Getting a crank rebuilt really isn't that expensive, either.

    I use YamaBond when putting the crankcase halves and cylinders together, then pressure test to about 8 PSI.
    I'm happy to do it myself, I have a printed copy of the manual at home so should be ok.
    I'm really trying to avoid pulling the bottom end out, I haven't looked into it thoroughly yet as I've been working, but tomorrow I'll remove the pistons and go deeper.
    How do you pressure test a crankcase?

  12. #19

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    Quote Originally Posted by butterbean_29512 View Post
    Looked back and saw your spark plug thread, and now the failure makes a little more sense. The #2 piston almost certainly failed due to water ingress. I've got a 1200r I'm working on now, and the rear cylinder failed due to water ingress. It also hydrolocked the cylinder and knocked the crank out of phase. The cause of ingress on the one I'm working on was excessive corrosion that completely ate the anodes out of it. Corrosion punched through the cylinder wall and bam! Took it out. Yours looks to be running a good while with a small leak. Check the head gasket for a leak....if no apparent leak then examine the cylinder(s) closely for corrosion. Your anodes are a good indicator of corrosion. If they're ate up it's a good bet you'll have cylinder damage. I didn't see any anodes. Are they under the cylinder head cover?
    I'll check for corrosion and have a look at the anodes tomorrow, should they be clearly visible?
    The middle cylinder did have water in the crank, the base and head gaskets didn't look that bad so i'm not sure where the waters got in.
    A couple months ago I took it to a dealership and got a new throttle cable installed, they also replaced the oil pump as it was badly corroded and cleaned up the throttle bodies. Since then I've taken it out twice, first time it ran fine for around 20mins then it just stopped mid cruise, restarted for 20 seconds and stopped again, i repeated this a few times to get it back to the ramp.
    I thought it was a flat battery as it showed 10v on the ski so I charged it up and then it ran perfectly on the trailer.
    Took it out again and got about 30 seconds of ride time before it did the same thing, it sounded different and I knew it was running on 2 cylinders. Again it ran fine on the trailer but that was when i decided to do the compression test.

  13. #20
    steve45's Avatar
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    Pull the engine.

    To pressure test the crankcase, you have to build a fixture with a low pressure gauge some hoses and fittings. I use a needle valve on mine and I run my compressor, then turn it off so the only pressurized air I have is in the line itself. You don't want much because you can ruin the brand new seals if you overpressure it. Apply pressure very slowly with the needle valve, then close it and watch it for about 10 minutes to make sure it doesn't bleed off. You'll have to figure out ways to block off the intake & exhaust, pulse line, etc. There are lots of videos online to walk you through it.

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