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Discussion Starter · #1 ·
Hi, guys:

My Yamaha SS 440 engine is stuck. Since the sled is nearly 30 years old, this wouldn't usually surprise me.

But I had it running this spring. The engine pulled over a little tight, so I wanted to be sure it would run. The carb was off and I put a bit of 40:1 premix in the plug holes just to hear it run. It started after a couple pulls, no problem. It would continue to run if I sprayed a little into the manifold. It wasn't run long as the fan was off and I didn't want to get it too hot. There were no sounds of mechanical distress that usually go with bad engine bearings. It turned over freely after being run.

The only thing I've done to it since then is change out the crank seals and put Marvel Mystery Oil down the plug holes. I was planning a gasket replacement and inspection for this weekend.

Since then, it has been stored indoors and hasn't been run any more. The entire PTO side seems stuck. I was able to remove the mag side head, cylinder, piston, and wrist pin easily, but the PTO side is barely moveable. I was able to slide the cylinder up to about 1" above the crankcase deck surface. The wrist pin moves freely but the piston is super-tight in the cylinder and the crank bearings won't move at all, not even with a breaker bar.

I've resigned myself to the idea that the crank and maybe PTO cylinder and piston need replaced.

But what the h*ll could have happened to it? It seems I did something to screw it up, but I'm completely mystified as to what it was.

Any input would be appreciated; I don't want this to ever happen again!

-Strato-
 

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Discussion Starter · #4 ·
JD, she was pretty smoky when she was running. I believe the premix was enough for it; I've heard of people disabling the oil pump and running them with only a 50:1 ratio, and no trouble.

RJ, it doesn't budge in either direction- no free play at all. It acts like I just pulled it up from the bottom of the Atlantic.

You guys think it was from lack of oil?
 

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From the bottom of the atlantic.. :laugh:

I don't know, I was just throwing it out there, but lack of oil would be my uneducated guess.
 

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Hard to say without pics, but it could be almost anything from frozen to the wall rings to bearing pieces jammed into the base to seized bearings. No real way to tell for sure until you take it apart.
 

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Discussion Starter · #7 ·
JD and RJ,

I just looked it over, and you may both be right. I had to twist the cylinder to get it off, it looks like the rings stuck. They are corroded, although they still move in the piston grooves. The bore still looks okay, although it's going to need honed before it's clear what shape the chrome is in.

Wrist pin and bearing look okay, but the big end bearing is seized solid. The inner main bearing is rusty. I suspect all the bearings on that side sat in water for an indefinite time. When I (unfortunately) ran the engine, it was just enough to distribute the water and finish wrecking my bottom end. The aluminum on the bottom crankcase half is dark gray on the lowest part, which the mag side doesn't have.

My guess is water got in at some point and didn't evaporate off, or if it did the damage was done before I ran my engine.

Arrrgh! :mad:
 

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Discussion Starter · #10 ·
You guys are right, it would cost more to overhaul the crankshaft then my entire sled is worth.

Assuming I can get away with replacing only the PTO side crank pin, the PTO con rod, PTO big end bearing, all mains, rings, wrist pins, circlips, and wrist pin bearings; plus two hours of press work, it's looking like about $550-$700. Not going to go there. And of course, that's assuming the jug hones out okay. If not, it'll probably be ANOTHER fifty bucks to get a decent (bare) jug. Argh.

I have a buddy who will sell me a fresh, complete, good-running SS 440 engine, w/Comet clutch, for $150. The catch is, a pal of his attempted to extract the clutch with a homebrew mess that left a socket rattling around INSIDE the clutch, between the crank stub and the extractor thread.

I'm thinking I'll go ahead and get it, then pop off the clutch using the grease gun trick. Once it's off and the grease is cleaned away, the socket ought to fall right out the taper side.
Just got to find out what the extractor thread is on a Comet 102-c.

Wish me luck, please!

-Strato-
 
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