Hone This

John Mulvihill · Posted: Mon Jun 28, 2004 6:35 pm Post subject: Ring tension redux

Thanks Pete!

Life is too short to do one's own testing<LOL>

Truthfully thank you for the direction. Now I (think I )understand what I'm looking for. From what I have found, initial ring tension allows you to start the engine. Pressure derived from the running combustion will allow for dynamic ring tension and actual compression. Now I have to find my middle ground.

Thank you.

John

Pete Muller · Posted: Mon Jun 28, 2004 9:48 pm Post subject:

Bill W Johnson · Posted: Thu Mar 30, 2006 10:27 am Post subject:

How do you adjust the tension on the Ring????

ted tucholski · Posted: Thu Mar 30, 2006 8:15 pm Post subject: Make em tight

I like to set my piston to cylinder clearence at .0015 to .002, I have also set them as tight as.001. You do need to break them in properly and take the time to do it right. This means track time. Many builders set them up looser so the customer can just go run them. The thing I like to stress on a rebuild is a light check of the ring against the cylinder wall. Place the ring about .015 below the top of the cylinder and hold it up to a light and see if the surface fit blocks the light out.
I am curious to here from other builders on ring size selection. I have begun to place the same ring size as is on the piston size and only go up a half size with piston at 05. 15. 25. etc.

Howard O'Chocke · Posted: Tue Apr 04, 2006 1:43 pm Post subject: Hone This

I know this post is directed towards the KT100, but am wondering what to do to the cylinder when replacing a ring in a CR125 Nickasil cylinder.

Tim Lewis · Posted: Wed Apr 05, 2006 8:22 am Post subject:

Pete Muller · Posted: Wed Apr 05, 2006 8:19 pm Post subject:

I've honed cylinders that were hot to the point of needing a couple layers of rubber gloves to hold onto them.

Didn't see any difference.

I have a sketch somewhere in a notebook of my "next gen" system for honing -- it would've pumped heated oil into the exhaust port, and cold oil into the intake port. I never built it, but thought about it quite a bit.

Steve O'Hara and I discussed this a lot back in the 70's.

It really makes no sense to hone a cylinder (like a Yamaha) "hot". If you think about it... there is 1100° gas going out the exhaust port, and ambient air coming in the intake port, and probably somewhere around ambient air in the crankcase and going up the transfers. The temperature gradients around the cylinder are VERY difficult to simulate, or even predict.

Bottom line: I personally believe there's more to understanding how the cylinder gets distorted when the engine is assembled than there is in trying to simulate running temperatures during honing.

I was able to run a direct drive Yamaha at .0005 clearance with no trouble... which to me would indicate that there wasn't a whole lot of distortion happening that I wasn't able to simulate during honing.
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Steve O'Hara · Posted: Thu Apr 06, 2006 12:58 am Post subject:

And just to add to Pete's thoughts on the subject.... the greatest source of distortion in the whole assembly comes from the dynamic loads the engines generate within themselves during the combustion process and there is no way to measure that distortion but you can sure see evidence of it in some motors more than others. The issue is most pronounced in the engines that have cast in lron liners like the KT100s and more so in the old Macs.... much less of a problem in the higher quality european motors. I have always liked Pete's approach which I would characterize as making the motor as perfect as possible in a static condition at room temp with everything bolted on and left on if possible or simulated if not.
One more thought on the subject of cross hatch and oil retention.... I got the best results in the Macs with an ultra fine honing approach that was almost cross hatch free and looked like the cylinder was almost polished. We used thin tool steel rings that had no chrome and a lot of care was taken to select rings that fit perfectly so there was no break in time at all. I usually ran a motor for just one or two laps very rich before going to full speed. I never saw any evidence that the lack of cross hatch had any effect on cylinder wall lubrication but it should be noted that we would run around 4.5 gallons of alky through the motor in an hour and the oil content was high so there was a lot of oil going through the motors compared to the modern gas burning setups.
Steve O'Hara

Tim Lewis · Posted: Thu Apr 06, 2006 8:25 am Post subject:

For whatever reason, in a V8, hot honing the block seems to make a noticeable difference in ring seal, especially after the engine gets a couple hours under their belts. The difference may simply be an issue of real estate. If you have a long bore, it's hard to keep the cylindricity. On a smaller stroke engine, it's just less cylinder to deal with.

I see what you mean about the exhaust on one side and the intake on the other. It seems like that would be a huge player in terms of cylinder distortion.

From what I've heard from an engine guy in a race shop, Honda has the best cylinder bore machining control. He said that some of their production stuff is better than they can produce on a race engine. They hone a 4 cylinder engine in something like 15 seconds. It's just amazing at the precision that some companies can produce. When was the last time someone had trouble with a Honda block? I've never heard of one. I've seen blocks out of an old CVCC with 200,000 miles on them that still had crosshatch.

Larry Andrews · Posted: Thu Apr 06, 2006 9:33 am Post subject:

Bill W Johnson · Posted: Fri Apr 07, 2006 1:14 pm Post subject:

Who can hard chrome a Mac Cylinder correctly to build it back up???

Tim Lewis · Posted: Sun Apr 09, 2006 8:51 am Post subject:

Ron LaFollette · Posted: Sat Feb 02, 2008 2:01 pm Post subject:

KURT RODGERS · Posted: Sat Feb 02, 2008 7:59 pm Post subject:

Couple of things to consider:
"torque plates" do not instantly distort the cylinder. Bolt the plates on in the morning and do not hone until after lunch or set it up at the end of the day and then hone the next morning. don't forget plates over the exhaust and intake mounts.
Hot hone - go to Salvation Army or Good Will and buy a electric skillet. Band saw off the sides and keep the flat bottom and the control. There is usually enough room inside the heating element loop to drill the head bolt pattern. Bolt it on with the torque plate (see above) . Before you go to hone plug it in and set to a temp (I did mine at 350º). When the light goes off start honing and let the control the on/off while you hone. You might want one top and bottom and try different temp splits. Plus they make your shop smell like pancakes.
Best honing oil - half kerosene half transmission fluid. Pumped liberally while honing. I have used a big plastic storage container and a "Little Giant" fountain pump. Bolt the cylinder/torque plate set up to a heavy chunk of steel and set it in the storage tank, turn on the pump and aim at the cylinder and hone away.
PS on hot hone - test measure the cylinder and piston cold and then at hone temp to determine growth. You will need to use a slightly different number when checking hot. Example the cylinder may grow .003 and the piston may only grow .002.