Honing cylinders

[slammers]

How many people hone their cylinders when replacing the ring on ringed glow engines? What method should be used? Would a automotive brake cylinder hone work or are they too abrasive? The engine I am working on is a YS 61 helicopter engine.

Thanks
Shawn

[Frank Klenk]

Hi Shawn,
I hone a cylinder when I replace a ring. I use a brake cylinder hone, it has fine stones. I use a hand drill at low speed (a variable speed drill is good). Use oil to keep the stones lubed. About 15 seconds produces a nice finish. You want a cross hatch pattern. Actually a 30 degree hatch is desired. My engines all run good. A bit of practise and you'll be a pro. Hope this helps.
Frank
ps ... can't hone a chrome liner, chrome is too hard and it will peel

[Propworn]

For honing oil mix 1/4 to 1/3 kerosene with the oil. It stops the stones from plugging up and is thin enough for the swarf to clear. Be carefull this will cut better than straight oil. Use the brake hones that have the adjustable tension collar and set it to minimum. You do not want to remove any material you only want to deglaze the cylinder walls. One thing that is most important is to check to make sure there is some ring gap when the ring is in the top of the cylinder. To do this put the ring in the cylinder then use the top of the piston or the skirt to make sure the ring is located square in the bore. Just push the ring down with the piston till the ring contacts the piston all the way around. Next start with a .001 feeler gauge and try and slide it through the gap. Keep working your way up till the ring grabs the gauge and wants to come out. The previous feeler gauge is the ring gap. I have found in most small air cooled engine a .002 to .004 gap is about right. You need this gap to allow for expansion when the engine gets hot. If there is no gap the ring ends will force against each other and then out against the cylinder walls and the engine will over heat and even sieze up. If the gap is not sufficient a few gentle swipes with a finger nail emery board should open up the end gap. Take your time and be gentle. Put the ring back in the cylinder and check it each time till the gap is right.

Good luck
Dennis

[AJCoholic]

OR... you can make friends with the local hot rod (engine rebuilding) shop where you live and if you ask real nice they may let you in on the weekend to use their Sunnen honing machine! :D

I am lucky to have access to that equipment. But the brake hones work OK for STEEL liners like Frank said.

For chrome/nickel you have to do something different. You need to make an expandable aluminum lap, and charge it with diamond lapping paste (coarse) then you can hone anything, including chrome.

I take it if it is a newer engine, the heli engines will be chromed (or nickel plated) even if ringed.

But you should go through about 2 to 3 rings before you need to hone the liner (usually).

Andrew

[Propworn]

I hate to say this but the new nickle/chrome cylinders should not be honed the plating is very thin and honing can reduce this to the point of possible peeling. Most of these in the hobby have no rings but the pistons are lapped to the cylinder. Ringed engines with the exception of larger gas engines are mostly all Iron sleave engines. These can be honed.

Dennis

[AJCoholic]

Dennis,
That is a good point, the chrome or nickel is allready thin and unless you are taking a minute amount off it probably is time to get a new cylinder if the liner is scored.

Dont forget that there are numerous ringed engines that also have a steel liner that is flash chromed too.

Andrew