Topic: Stuck Piston Rings.......how to release 'em ?

[Spanner 1]

So this 750K8 motor is now apart, in the process of dealing with surface rust issues, mostly clutch basket and conrods have oxidation.
Took #1 and 2 pistons and rods off, but both have stuck rings ( 3+4 are  O.K. )
Any ideas how to ease the rings out of the grooves, want to re-use them, only 16K miles on motor...... I can't wait to measure ring gap in the bores to see how much wear in 16K...

[bistromath]

Penetrating fluid. Everyone has their own recipe for a magic formula to release stuck pistons. Mine came from someone on this board and is 50/50 acetone and ATF. Let it sit for a week or two, and get a breaker bar on the crankshaft. Rock it back and forth every day until it breaks free.

[sloppydawg123]

Am I reading this wrong, seems like all pistol are already removed, but the rings are stuck correct?

[bistromath]

Oh, right. Poor reading comprehension. In that case, soak with ATF+acetone, wait a while, beat with wooden dowel and rubber mallet until convinced.

[NitroHunter]

"The April/May 2007 edition of Machinist's Workshop did a test of penetrating oils where they measured the force required to loosen rusty test devices. Buy the issue if you want to see how they did the test. The results reported were interesting. The lower the number of pounds the better. Mighty interesting results for simple acetone and tranny fluid!

Penetrating oil . Average load .. Price per fluid ounce
None ............ ..... 516 pounds .
WD-40 ............ .. 238 pounds .. $0.25
PB Blaster ......... 214 pounds .. $0.35
Liquid Wrench ... 127 pounds .. $0.21
Kano Kroil ........ 106 pounds .. $0.75
ATF-Acetone mix.. 53 pounds .. $0.10

The ATF-Acetone mix was a 50/50 mix (1 to 1 ratio)."

FWI - ATF makes good assembly lube on the piston skirts and in ring grooves. We do this on the dragster when we shove pistons between rounds.  Also it keeps unpainted tubing from rusting.

[Spanner 1]

Thanks, guys...just to be sure were all on the same page, let me clarify the two pistons are ' on the bench' with stuck rings. Any point in heating them, propane torch or oven ?

[tlbranth]

My 750 sat for many years and the engine wouldn't turn. I got the cylinder block off by using ironwood wedges. The rings were seized into the pistons but I managed to coax (beat) them out of 3 pistons but not the 4th. I had to buy a new piston. The old one, with rings still welded in place, is now a pencil-holder in my cabinet shop. I think the steel rings and the aluminum piston reacted and chemically bonded. Use penetrating oil to free up the rings you can but figure on, at least, buying new rings. Good luck

[BVCB650]

Yea, 2 or more different types on metals have been known to do that.

[Whaleman]

Spanner, This is a somewhat controversial subject. Here is my opinion which I have expressed many times. Take the pistons and the cylinders to a shop. Have the rings removed and the pistons cleaned by media blasting. Have the cylinders honed. Buy a new set of rings. Lap in the valves and replace the valve guide seals. Reassembly and have a,"as new" engine. With all the labor, gasket sets and other( oil, filters, exhaust gaskets, Just plain work). Life is short, and you might as well have a new running engine that you trust. Thanks,Dan

[Spanner 1]

O.K., Whaleman, but that just takes care of the top-end....my thought was to replace the main bearings and the big-end bearings, free up the rings and give the bores a light hone.
I would think 16K on the motor and the top-end would be O.K. It was on my K1, 24K and 10 year sit also my A, 32K and 7 year sit outside before I got them  and fired them up.......no smoke from either, or was I just lucky twice !!

[Spanner 1]

Shameless bump for any more ideas?

[bucky katt]

go get an old crockpot at a pawn shop or goodwill store, put the pistons in it and pour enough cheap motor oil in to cover them, set it on low overnight.

[Spanner 1]

Piston Ring Stew !,,,,should of thought of that !,,thanks. Bucky.

[JohnG]

I have a large can of Gunk carb cleaner  (gallon or so).  Lethal stuff... horrible.  I have an old -300- piston with stuck rings.  I will stick it in there for a couple of days just to see what happens.  If I can't find it at that point... well....  But it might work.

[Alan F.]

I just freed up a CB400T which had sat for a year indoors without plugs by just pouring a few (dozen) drops of Marvel Mystery Oil into the plug holes.
I let it sit 5 days at room temp then turned the stator rotor by hand with a 17mm wrench, it freed right up.

I'm told that with heat added it's great stuff.
-Alan

[JohnG]

Marvel Mystery Oil!!! YES!! Great idea!!   

[bucky katt]

the crockpot trick is also good to prep a new drive chain or shell bearings before you put your bottom end back together. one of the neat tricks i learned from Bob Donaldson, my BMW instructor at AMI.

[Spanner 1]

I'll try the crockpot fix over the weekend and post the results a.s.a.p.

[JohnG]

Obviously you crockpot guys are not married or those are the discarded crockpots or ...

I baked a head in the oven in 1984 that I had done with Kal Gard Gun Kote and still haven't heard the end of it.  Every time she looks in the oven she wonders what's been in there when she wasn't around...

[bucky katt]

i found a crockpot big enough to fit a human head in it at a pawn shop for 5 dollars, it lives out in my shop.

[Kframe]

I have a large can of Gunk carb cleaner  (gallon or so).  Lethal stuff... horrible.  I have an old -300- piston with stuck rings.  I will stick it in there for a couple of days just to see what happens.  If I can't find it at that point... well....  But it might work.

Man you said it, that Gunk carb dip is truly awful and amazing!  Eats through all sorts of crud.
Just try not to breathe the fumes, it really rips up the throat and is no good for the gray matter either! 
My carbs are sparkling clean now but I think I lost a couple brain cells in the process.   
-K