Frozen motor on an SL125

[newmaac]

Hi folks,
I have an ancient Honda SL125 that has spent the last 3 years outside in the elements.
I recently went out to work on it and found that the motor is now siezed-up. I had previously removed the carb to re-build it. When I did so, I wrapped the head with plastic, to keep water out of the combustion chamber. Well, that idea sucked, and now it is frozen.
I have removed the plug and added Marvel Mystery Oil. Actually I dumped a bunch in thru the intake and exhaust ports as well.
So far, I have not been able to break it free. (it has soaked for a week)
I assume that I have better leverage with the motor assembled and installed, so that I can just rock the bike back and forth while in gear, but I am getting tired of waiting.
I am thinking that I might just try to dis-assemble it and knock the piston out with a mallot, but there is a good chance that I won't even get the cylendar to move.

Any suggestions before I start "rippin and tearin"?

Thanks,
Mike

[TopCatGr58]

Hey Mike,

Sounds like you have a nice thick layer of RUST on the inside of the cylinder above the piston! You might end up breaking a ring trying to shove the piston up past/thru that rust!

Sounds like you'd be better off pulling the head, and then you should be able to pull the jug UP since the rust is probably above the piston, whereas the oil "MAY" have helped keep it from forming below the piston?

Then you can either get the cylinder honed, or bored depending on how THICK the rust is?

Hindsight is 20/20, a bit of oil inside the sparkplug hole and intake might have prevented this while the carb was off!?
T.C.

[ZXDavid]

You could try heating the motor up with a heat gun or a propane torch around the cylinder area. Ive actually seen that work at times.

[newmaac]

T.C. you were RIGHT ON!!
I pulled the head and jug.
There is surface rust ABOVE where the piston was. everything is clean from there on down.
Was able to disassembly the top end with no visable damage other than the cylendar wall.
Now I am trying to locate a small cyl hone.
Any ideas as to where to locate a hone for a 1.76" jug?

I have tried eBay and several m/c parts sites. Everything that I have found is too large.

Thanks in advance,
Mike

[TopCatGr58]

I don't know how well it would work, but you might be able to use an automotive BRAKE MASTER CYLINDER HONE , I've seen them and they seem to expand to a couple of inches!?
T.C.

[jetmechmarty]

If the cylinder is closed, you can break it free with a grease gun. I made a grease fitting from an old spark plug. Just break away the porcelan center and weld or bolt in a grease fitting. It the grease has no where to go, the piston WILL break free. On the four stroke engines, you just have to pick the cylinder that has the valves closed. I'm here to tell you a hand held grease gun will do the job. A buddy of mine just did the same thing on a 400 ci V8 that had been stuck for 20 years!

Maybe Fred in 'toon will chime in as I first learned of this trick from him over on the XS650 list.

[fredintoon]

Grease gun

Hi Marty,
nothing to add to your post except to say that a good side-lever grease gun can produce up to 10,000 psi. If that pressure won't move a piston I dunno what will.
Fred Hill, S'toon.

[DiverRay]

Newmaac,
I may have a hone, but I don't know if I'll have the time to get it to you. give me a call and we can talk about it.