Have a stuck ring on a 77 R100. Its the top one. There is so little of a gap I can barely get my smallest screwdriver in the gap. Its a very small one that I am sure the end will snap off with much pressure. So I sprayed with Liquid Wrench and let sit overnight. Still no budging. I tried to catch the end edge with a screw driver but dont want to booger up any edges on the piston. I am going to try dropping it in some boiling water next. Anyone have any other tricks that dont involve me whacking the crap out of it. I could use some heat but hate the chance that I might put too much to it and warp the piston. Thanks in advance for any tricks.
Before going nuts with boiling water; The first thing i try is a mixture of half acetone and hal ATF. re-apply avery 20 minutes/half hour. Then use an industrial heater. In lieu of that, try a good hand-held hair dryer around the cylinder (not the piston). Keep it moving. When the aluminium is HOT, give the piston a jolt with a rubber hammer. This is assuming the engine is out?
Sooooo sorry to mention. The piston is out of the cylinder. Its frozen in the piston gap, compressed all the way around in the seat of the piston. Sorry.
It's corrosion or carbon sticking it. For sure, don't lever it out. Patience is important if you're going to save the thing. After it's all cleaned up, use some good aluminum cleaner to eat away the corrosion. Or let it soak in some pinesol or carb cleaner to remove the carbon. Heat it up, apply the aluminum cleaner, let sit. Over and over. It may take a while, but patience will eventually win the day.
don't pry on it, it will break. i've used heat/cool cycle to unstick them. you may be able to use a ultrasonic or other chemical methods (atf/acetone works well). heat is the fastest way. otherwise time and patience.
Something that works for me. In an old 2 quart pot, pour 1 quart of ATF. Place piston in the pot, supported slightly off the bottom. Place pot on hotplate and bring to a warm temperature. DO NOT BOIL!!!! Let sit in the warm ATF for an hour or so. Take out and rinse with a good clean solvent. This procedure usually gets the ring loose enough to remove.
I never applied heat, and it always worked. But, waiting time did vary; sometimes over-night.. sometimes a month. Additionally, I always used 100% ATF, but I need to remember the 50/50 ATF/acetone tip for the next attempt. Now that I think about it, I'd be interested in applying even heat if I had access to a spare oven.
Would a piston warp with heat? I thought they're made for dealing with heat? Or is it the cylinder & rings that stops it warping?
i would think it would melt before it would warp. i heat 'em with mapp gas (not too much - mapp will melt aluminum...) then quench 'em in oil. work everytime. or you could do the slow and cautious way. your pick! either way, they're stuck and probably need replaced. i'd be more worried about damaging the lands then the rings....
If you use heat, do it sparingly. I only bring mine up to a max of about 150F for about 30 minutes. Then let it cool overnight. Come morning, everything moves and comes apart nicely. One of these days I am going to buy one of those nice ultrasonic cleaners.
I use an old screwdriver specially modified for this purpose. I grind the end of the blade in such a way that the blade has parallel sides instead of a wedge, and then grind an angle on the tip. As long as the screwdriver blade is thin enough to fit the ring groove easily, it'll do the job fine and without damaging the piston. A few gentle taps on the screwdriver with a hammer are usually all that's required to get the ring moving. You'll be able to use a pair of pliers to remove it once it's "unstuck". A squirt of penetrating oil may help, heat may help too, but I've never required either. However, you'll need to use your own judgement to determine how stubborn the ring actually is and how best to attack it. Here's a really rough sketch to show you what I'm talking about:
Just saw you're replacing the rings, heck use the tool Max described and pop it loose. I had the same issue on a DRZ, let should have just re-ringed it, but in a weak moment we chose to punch it out to from 400 to 434. Stuck ring was caused by a gummed up ring grove, either gas or carbon. I'm not sure which. Check out the DRZ thread below.