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97 Gsx 787 crankcase full of oil

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Well I'm glad I decided to pull the engine. The rear piston and cylinder are toast. I can see through the piston next to the exhaust port! I wish I could figure out how to upload pictures
 
Well I'm glad I decided to pull the engine. The rear piston and cylinder are toast. I can see through the piston next to the exhaust port! I wish I could figure out how to upload pictures

If you use TapATalk it is very easy to upload pictures...
 
It was only hydrolocked with oil. It was free once I pulled the plugs. most of the oil squirted out the front cylinder, I guess it's because the oil just went through the other piston haha. I got your message so I'll try again to get pics up when I get in the house
 
Possibly the ring caught the exhaust port and tore it up. From the picture it does not look like a burn hole, but more from mechanical damage.
 
My guess is it started burning up and the pin fell out letting the ring spin and catch on the port. It looks like a little bit o f both happened
 
And that's why you always check compression before you biy


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I checked it on the machine he advertised as running. The one I'm working on was advertised as a parts machine so I wasn't too worried. It wasn't till I got it home that I thought of getting it running
 
This certainly didn't happen b/c there was too much oil. It does sorta look like maybe the ring snagged in the exhaust port judging by what looks like a broken ring land, especially if the ring is bent. The end of the ring shouldn't be exposed to the port where it can snag in the opening, the ring may have rotated if the locating pin failed.

Other things that can overheat the piston and cause it to melt is low octane from crummy or stale fuel or a lean air/fuel mixture (piston burning detonation occurs when combustion stops too early).

If the piston overheats(too much heat causes piston to expand), the oil film is in jeopardy of failing as the flash point is exceeded. Once the oil film fails, it's all over with.

Pre-ignition can break a piston or ring land as well, it's the most destructive force that can occur in a cylinder. This occurs if the fuel mixture is ignited before it's compressed, a spark plug of too hot of range can cause this or even an overheated piston.

edit: To add a little more, low compression means there will be too much blow-by. The clearance between the piston and cylinder wall plays an important part in transferring heat out of the piston crown through the rings and oil film into the cylinder wall. If there's too much clearance or the rings have collapsed, the piston temp can exceed "safe" levels and cause the oil film to fail. This is why every 2-stoke motor will eventually seize if at some point it's not rebuilt first, to compensate for normal wear, so monitor your compression often enough to catch a worn cylinder before the piston overheats.
 
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Thanks for all the good info there

My project is stalled for a few days while a wait on a flywheel puller. Once I check the crank out I'll decide which way to go with this. If the crank is bad I'll probably buy a complete rebuilt engine, it doesn't seem to cost too much more and I'll have a warranty. If the crank is good I'll head to the machine shop and see what they can do with my cylinders
 
Well the other day I got impatient waiting for the tool and I bought a rebuilt engine from a guy locally. I figured I'll take my time and build the blown one up for the other machine.
I got the tool yesterday and was able to check out the bottom end and everything looks good and spins nice and free. The inner seals are tight and don't look bad so I am thinking I'll be good to seal it up good and put it back together. My question is if there is anything that would be safe to spray all the bearings down to clean out any junk that might have gotten in there?
 
Here's what I'd do....
If you're contemplating flushing the bearings in the lunched motor my bet would be they were spinning while aluminum shards were bouncing around in there so doubt you can flush that contamination damage out.

For non-sealed rollers I use a very clean parts washer tub with filtered electric pump to flush dust and dirt out of bearings if present, diesel fuel should work as a fluid or the correct (expensive) parts washer fluid. Don't spin them while totally dry of lube else the polished surfaces become scratched, once clean then lube with light oil for checking and fill with camshaft grease (assembly lube) before assy. I guess a new crankshaft should have instructions enclosed?
 
Filing a crankcase with diesel fuel can work well for pickling a water-flooded motor too, to try keeping it from rusting up until you can get to it.
 
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Just an update. Im waiting on the alignment tool, pto tool, and pump tool. The motor is ready to drop in once I get the pto coupler thing off the old crank.

With the amount of specialty tools you need for these things I wish there was a place on the forum to list tools you have and where you live so people can share with each other. He'll I'd have been willing to pay someone locall to borrow them. I'd be willing to help people out too
 
Its been a while, but I got a lot done today. I got the motor in and aligned, rebuilt the pump, and put a new wear ring in. The other day I cleaned the carbs, cleaned the fuel tank out , and replaced all the fuel lines.
I did manage to fire it up and run it for a second but I wanted to check with you guys before I run it. Is there anything special I need to do for a new motor? I really don't want to blow it up
 
Its been a while, but I got a lot done today. I got the motor in and aligned, rebuilt the pump, and put a new wear ring in. The other day I cleaned the carbs, cleaned the fuel tank out , and replaced all the fuel lines.
I did manage to fire it up and run it for a second but I wanted to check with you guys before I run it. Is there anything special I need to do for a new motor? I really don't want to blow it up

I am sure others with more experience will chime in but I know the original Seadoo Manual for my 657X engine stated to put 30oz of the oil in the first tank of gas and to follow a break in schedule for the first 10 hours of not excessive WOT and also to vary the speeds.
 
I am sure others with more experience will chime in but I know the original Seadoo Manual for my 657X engine stated to put 30oz of the oil in the first tank of gas and to follow a break in schedule for the first 10 hours of not excessive WOT and also to vary the speeds.

Ok thanks, thats kinda what I was thinking, it's similar to what I've done with my snowmobiles
 
I am sure others with more experience will chime in but I know the original Seadoo Manual for my 657X engine stated to put 30oz of the oil in the first tank of gas and to follow a break in schedule for the first 10 hours of not excessive WOT and also to vary the speeds.

A++++ On the premix insurance policy.
 
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