Recently Frozen Ringed Motors!

OK,engine experts,I have purchased my OS Max H 40 R/C off e**y,it is
new and un-run,and appeared at first glance to be frozen solid,but
when I bolted on a prop.and squirted in some oil,it turned over fairly easy. After more shots of oil and much flicking,it is still
not as free as it should be. It has 2 piston rings,and I am guessing
that although the motor is turning over,the rings are still stuck in
their grooves. Should I free the rings before starting(and if so,how)
or will they loosen up once it is running? Also,I need some advice on
what size venturi to fit,and also the best NVA for a Max 40 H. Mine
has the thin un-grooved prop.drive,and appears to have a front race.
In answer to Bill Sawyer on my last post,I am having all sorts of
problems registering,so please be patient.

The rings probably aren't as much a concern as the bearings are. If it was gooed up, they may be stuck and not roll freely as they should. I'd squirt some Marvel Air Tool Oil in it and see if it gets any looser. You can try a few SHORT runs and see if you still have compression and all, and how it "feels". Make haste slowly.

Take off the backplate and drop that sucker in an antifreeze bath. Tomorrow, take it out, rinse it and lube it up and if the bearings aren't rusted mess, all will be well.

If of course the bearings are toast, you'll feel it after all the other gunk is cleaned out of it. Then you'll just need to order some new bearings.

If the ring is gummed up, you may need to pull the piston and let it soak by itself in the hot antifreeze, that will clear up the groove. Meanwhile, you can spin the crank in the bearings and see how they feel.

Right and what ever you do, DO NOT remove the rings unless you have a new set on hand. Usually running with some Klotz and castor mix in the fuel will clean up the goop and free up the rings. Two minute rich runs should do the trick.. Like it has been said, make haste slowly.

How about the wrist pin? Although I have not yet experienced the problem, I've read about guys having a stuck wrist pin. Is this a common or rare thing on a gummed-up engine?
If I remember correctly, this occurrs more in an engine that has been run hot, not a NIB situation.

> How about the wrist pin? Although I have not yet
>experienced the problem, I've read about guys having a stuck
>wrist pin. Is this a common or rare thing on a gummed-up
>engine?
> If I remember correctly, this occurrs more in an engine
>that has been run hot, not a NIB situation.
>
> George

On the wrist pin issue, this will be a result (usually) of castor oil carboning up. It will usually take a lot of running for the problem to occur. Sometimes the rod will freeze on the wrist pin and then the wrist pin must turn (not good) in the piston. Otherwise the rod turns on the wrist pin. The problem with the wrist pin freezing is improper expansion. It keeps the piston from expanding uniformly.

But if the rings are frozen (quite possible) if you run the engine in this state you can very quickly ruin the rings. Remember, the piston is going to expand, and if the rings cannot float in their grooves, what happens to them? (Well, as you can guess, it is not going to be good). Disassembling the engines is not good, but it is still probably better than running with stuck rings.

The original needle for these engines was a long .135 diameter. With it a .261 to .272 ID venturi was in order. Since you won't (probably) be able to find the original needle any more (the new ones for the OS are too short) you will probably have to substitute an ST type or similar. That will mean drilling the cross hole larger to accomodate the .155 diameter of the new needle. With the ST needle a venturi of .281 to .290 ID would be good (measured in inches. We in the US have never figured out how to do metric.)

>In answer to Bill Sawyer on my last post,I am having all
>sorts of
>problems registering,so please be patient.

7477? Just send me an e-mail if you are having troubles setting up an account and I will do it for you (if I can sort out yours from all the viruses). Some people have experienced troubles due to firewalls or popup blockers. (If you have a pop up blocker, hold down the shift key when clicking on the register link.)

Stinkin viruses, getting returned emails from folks that I'd never email in a lifetime. But somebody that has my email address does, so I get returns, lots of em.