How to free a seized motor

[tobydmv]

Whats your favorite method? I have a nice 250 to liberate. Piston is about half way down the bore. Cylinder was seized so the rust shouldnt be too bad.

1. Fill cylinder w 50/50 ATF and Gas or Charcoal starter fluid(burns slower and safer). Pop w drift and mallet.
2. Degrease and fill cylinder with vinegar. Vinegar eats rust. Wait 48 hours, empty it, and fill with boiling water. Pop w drift and mallet.
3. Grease gun spark plug tool. Use grease pressure to drive piston loose.
4. Metal plate mounted on cylinder studs. Metal plate gets tightened down on a drift which drives piston down.
5. Your favorite choice here

What to use for a drift? Round wooden fence pole? Might chisel a notch in the end to fit the piston arch.

[Nick]

Whatever you do, don't rush it. After soaking with your favorite penetrant oil, heat the piston/cylinder and let it cool, then repeat the process again a few days later. Some people have had success using a jack between the top frame rail and the piston.

[motoital]

This is what has worked for me. First I fill the cylinder with a product called evapo-rust. I keep a close eye on it and it usually only needs about 24hrs. After that I fill with a mix of acetone and auto trans fluid and finally use the grease and modified spark plug method. But some notes. You can use any anti rust product that's not a jell as you want to be able to drain it. I am looking into a product that they use on dairy tanks as it is cheap and non toxic. I'm not familiar with the atf mix you mentioned and I'm sure it work great but google acetone+atf. the grease method only works if the piston isn't at the bottom of the cylinder. Also it works best if it's packed into the bore as to avoid air bubbles.


Good luck!

[motoital]

On a side note. If you haven't pulled the side cover already you might want to check and make sure the primary gears aren't rusted together if the bike has been sitting outside. Your post was timely as I needed to free a stuck two stroke I have. Here is a pic of the rusted cylinder and with it full of rust remover. Lets see how long it takes.

[tobydmv]

Motoital, I have pulled the R side cover and man what a chore that was! The clutch side wont come off yet but half the bevel side is off. I tried putting a breaker bar on the crank and turn ccw. It didnt budge and I dont want to damage the crank. So last night I filled it with light oil and charcoal starter 50/50 or so. Lit it on fire and it burned for about 20 minutes nice and slow. Gave it a few taps with a small sledge. Cleaned it out and filled it with Kroil. Repeated the process. Its still stuck so I will keep on it for the next week or so.

ATF / Acetone is home made Kroil. Somewhere on the inets is an article by Popular Mechanics or like minded types. They reported that the home made mix was better at loosening parts then any store bought item. Acetone is $10 a pint I think.

[motoital]

If you remove the small clutch adjustment cover and use the claw end of a hammer it should come off. They also make some really nice hard plastic wedge tools to adjust panel gap for cars that can be used but be gentle. The timing side can be tricky. A rubber mallet used at the right angle can be used to get it started. Then those plastic wedges help a lot.

[tobydmv]

Yay, my motor is finally free. I went to Northern Tool and bought a 50mm socket that was on sale for $5 and a 3/4" extension. The OD of the socket was about 71mm I think which was really close to the outside bore. Then used lots of map gas and pounding and it moved 2" down. I then used the crank nut to raise the piston and cylinder up off the case. I put 2 sockets in for spacers and drove it down a bit more. Then I had a friend suspend the cylinder off the table and drove it out finally. Now i'm on to find a replacement. The Omegas sure are lovely to look at but i'm hoping to find some OS NOS. Anyone have an extra?

[double diamond]

Your clutch cover may be difficult to remove because the end of the crank could be mushroomed (from a heavy handed previous disassembly) and then forced onto the bearing in the clutch cover that supports the end of the crank. There is a tool that screws into the round threaded inspection plug hole that is concentric with the crank. The tool is basically a plug with the same thread as the inspection plug, with a 10mm bolt in the center. Screw the puller into the clutch cover and screw the 10mm bolt in to force the crank off the bearing (or push the bearing out of the clutch cover). Helps to heat the cover a little around the bearing. If the end of the crank is mushroomed like this and the crank was forced into the bearing, using the claw hammer technique or wedging/prying can potentially crack the clutch cover.

[tobydmv]

Your clutch cover may be difficult to remove because the end of the crank could be mushroomed (from a heavy handed previous disassembly) and then forced onto the bearing in the clutch cover that supports the end of the crank. There is a tool that screws into the round threaded inspection plug hole that is concentric with the crank. The tool is basically a plug with the same thread as the inspection plug, with a 10mm bolt in the center. Screw the puller into the clutch cover and screw the 10mm bolt in to force the crank off the bearing (or push the bearing out of the clutch cover). Helps to heat the cover a little around the bearing. If the end of the crank is mushroomed like this and the crank was forced into the bearing, using the claw hammer technique or wedging/prying can potentially crack the clutch cover.

I have a set of flywheel pullers in the shop. I remember thinking it was too much money to buy the set and i'll never use them. I think i've used almost every puller in there over the last 3 years. One of them fit into the clutch cover plug and helped remove the cover. There is a lot of evidence of "screwdriver entry" around the cases though. The bike has been sitting outside in South Carolina for a "good long while" as they say.

[DewCatTea-Bob]

Yay, my motor is finally free.
Now i'm on to find a replacement. The Omegas sure are lovely to look at but i'm hoping to find some OS NOS. Anyone have an extra?

____ Here's a couple links to past related thread-posts which may be of interest to read-through.
viewtopic.php?f=3&t=413&p=2863&#p2863
viewtopic.php?f=3&t=1561


Hopeful-Cheers,
-Bob