RE: Piston Ring End Gap
 

Is there something special about Bowman's rings? Does he have a website?

RE: Piston Ring End Gap
 

Funny, I was sure your post was about Frank even before I opened it. [sm=spinnyeyes.gif] I just got done locating Frank on the internet. Here goes:

Frank Bowman
1211 North Allen
Faemington, NM 87401

1-505-327-0696

[email protected]

Are his rings special? I don't know but his name comes up here all the time so I'm going to find out.

"Along with my new ring, Mr. Bowman included a listing of engines he makes rings for. The number and variety of engines in the listing is astounding. Mr. Bowman also includes a short paragraph on the care and feeding of new piston rings. He manufactures repro and current piston rings for our modeling needs. He can make standaed standard and Dykes type rings. If he doesn't have the ring you need in stock, you send the piston and cylinder and he will make the ring. Prices are $7.50 up to $9.50. His work is of the finest quality. He can be reached 6PM to 9PM Mountain Standard Time weekdays."

This guy has my head bobbing.

I didn't spend a-lot of time here but you should check out:

http://www.rcfaq.com/ANSWERS/ENGINE/INDEX.HTM

Regards,
Bill

RE: Piston Ring End Gap
 

Hey GhostRider I just got what must be a new E-mail address for Frank Bowman.

[email protected]

I don't know which is correct. I'll let you know.

Bill

RE: Piston Ring End Gap
 

Ringmaster is the correct one

The other is his old address

RE: Piston Ring End Gap
 

Thank you w8ye. Why the heck didn't I just ask you in the first place? Too soon old, too late smart.

Bill

RE: Piston Ring End Gap
 

I just heard back from Frank Bowman. As w8ye said Ringmaster is the correct E-mail address. To quote Frank:

"Quality at a fair honest price. Making a good ring is a Skill. Making a fine ring is an Art."

I'm signed up. Thanks to everyone for the support on my ring gap issue and for the reference to Frank Bowman.

Best regards,
Bill

RE: Piston Ring End Gap
 

While we're on the topic of rings...I'm sure this is addressed somewhere else, but I couldn't find it...What is the proper cylinder treatment when replacing a ring? I've built plenty of car and bike motors but I'm not sure how that experience translates to RC motors, even if I could find a hone to fit the small bore. Also I'm not sure that an agressive honning would would be very good for an AAC cyl. I do know not to use anything more than a clean pencil eraser on the valves/seats in the Saito AAC cyls, but not anything on cyl prep/honing/deglazing.

I've got a Saito 90R3 that seems to have low comp on one cyl. should I replace just the one ring or all of them and start all over on the break-in? This is a very lightly used motor, new to me that flames out consistantly on the same cyl. New H9 super-plugs and lash adjusted all 'round. Omega 15% castor/synth.

Thanks!

RE: Piston Ring End Gap
 

Deglaze the cylinder with 400-500 wet/dry sandpaper carefully before use with the new pistonring. Break-in the engine first before you get full power out of the engine.

RE: Piston Ring End Gap
 

Hey Frets, I'll give you my two cents and yes, I've rebuilt a few engines too. My first two cycle rebuild was a West Bend engine on an old go cart. My dad was looking over my shoulder the first few times and he was BIG on new rings in a two cycle and "cross hatch" cylinder honeing with an electriic drill, a bucket of kerosene and a cylinder hone. I made sure I had no crankcase leaks and fresh piston rings. I used to race my friends who had the same engine and go carts and could always blow them away. Their dad thought that my father was performing some sort of voodo on my engine because my dad was a wrench of great renown locally. Later in life I had a Kawasaki 500 H1 triple and rebuilt it a-lot with the ol' ring and hone technique. What I didn't realize was that there were different grit stones available for cylinder hones and performed so many "ring jobs" that I prematurely wore out my cylinders. I later learned about the magic of molybednum coated rings and their rapid break in capabilities and that you NEVER HONED A CYLINDER WITH ANYTHING COARSER THAN A 600 GRIT STONE that was being prepared for moly rings. So I learned. I recently bought a used Enya .19 with the piston rusted fast to the steel liner and the liner subsequently rusted to an interference fit in the aluminum crankcase. A fair amount of propane gas heat and some judicious tapping on the piston crown with a hardwood dowel freed everything up. I cleaned up the piston and cylinder liner with a very gentle wire wheel in my Dremel rotary tool. Then I carefully "honed" the cylinder with a slotted wooden dowel and some 600 grit wet/dry paper lubricated with G96 gun oil (sort of a WD40 to the power of two). I did NOT want to see bare shiney metal in the cylinder, I wanted Smoooooth and polished. I spent very little time in that cylinder with the 600 grit paper. I have now this .19 and another that never suffered any indignities. The really sick little .19 has superior compression. I will never touch a ringless engine with anything more abrasive than a paper towel. If the piston/cylinder fit fails I will replace both at the same time. On a ringed engine I will go no further than 600 grit paper and attempt a nice "cross hatch" pattern in the bore - and hone for a VERY short period of time.

As far as your Saito goes you could have a broken ring. The circlip retainer on the wrist pin may have come out of it's seat and allowed for scoreing of the cylinder wall. If your Saito is a low hour engine I wouldn't be concerned about a taper worn in the cylinder. Possibly a brake cylinder hone would fit your cylinder but I wouldn't think of it. Hone it too much and you better have a source for oversized pistons. You can measure the cylinder with a bore gage and micrometer or a dial vernier caliper but a low hour engine shouldn't have a worn out cylinder. I would tear it down for inspection and if your wrist pin retainer failed and scored the cylinder buy a new piston and cylinder. On your tear-down put the same piston on the same rod and the assembly back into the same cylinder bore. Should you remove the circlips, wrist pin and piston reassemble with new circlips. Make sure the open end of the circlip is in either the 12 oclock or 6 oclock postition. Better yet, try to locate some teflon wrist pin retainers and lose the circlips. I would be curious if Frank Bowman could fabricate some brass or aluminum wrist pin retainers. I'm going to ask him. Heck, if he can fabricate piston rings my little ask would be a snap.

Anyway, listen to the plethora of responses I hope you get from the fine guys here who collectively present us with hundreds of years of experience. My two most memorable questions regarding control line leadouts and now ring end gaps have produced volumes of responses and books full of knowledge. I vote we change the name of this website from RC Universe to RC University.

Regards,
Bill

RE: Piston Ring End Gap
 

All current production Saito single cylinder engines have a cylinder that is chromed right onto aluminum.

If you do any honing on one of these you are asking for trouble.

The Enya four stroke has a steel liner

RE: Piston Ring End Gap
 

OK ladies and gentleman. Here's the word from Bowman Mountain:

Frank's rings

* are made from fine graned cast iron and heat treated to 1,850degrees F
* come pre gapped to his bore gage or ungapped
* end gap recommendations on engines under .70 c.i. - .001", .70 c.i. and over - .0015 to .002

I'm buying all of the information and at least two rings. I guess I'll have to tear down my new Enya SS.40BB to see if it's ringed and order one for that too.

Regards,
Bill

RE: Piston Ring End Gap
 

Thanks w8, in that case I wouldn't hone it at all except maybe with a paper towel.

Regards,
Bill

RE: Piston Ring End Gap
 

I don't know of any ringed SS40BB Enyas?

You can take the muffler off and look in the exhaust port to see if it is ringed

RE: Piston Ring End Gap
 

Thanks w8, I don't think it's ringed either in spite of what the Enya literature that came with the engine said. I don't wish to tear it down. If it ain't broke don't fix it. I have gazed into the exhaust port and could see no ring.

How in the world did you obtain such a wealth of knowledge about such a variety of model engines? Do you own one of every engine ever built? You are an encyclopedia!!!!

Regards,
Bill

RE: Piston Ring End Gap
 

I'm 64 years old and have built model airplanes since I was 6 years old.

I was a participant on RCOnline for 3 years before RCUniverse was thought of and have been on RCUniverse ever since it started.

I had 58 two stroke engines at one time but have sold most of them.

I only have around 30 engines now and most of them are four strokes. The two strokes are gas engines.

I don't know it all far from it, but the great amount that I don't know, there are several other guys on here that do know a lot more than I do.

Together we have you covered

RE: Piston Ring End Gap
 

That explains a whole lot. I'm very glad you are onboard. Thank you.

Bill

RE: Piston Ring End Gap
 

A few years ago I broke the ring in my '70s vintage Profi .61 two-stroke. My heart sank. I figured the engine would be sidelined for years until I stumbled on a replacement. I assumed when I did find one, it would be a fortune. I would have no choice but to pay the asking price or the engine would never run again.

An e-mail to Frank, $10.00, and a week later Frank sent me a new ring better than the one it came with. This engine had been out of production for 20 years! Really a fantastic ending. I still fly this engine on my LT-40. As far as I'm concerned, Frank is a gift to modelers. I haven't worried about a ring in a model engine for decades.

Please measure the gap when you get your new ring. I will be very surprised if this is the gap on an 4-stroke ring.

Bill

RE: Piston Ring End Gap
 

Yeah for what Frank charges I don't know why he bothers. Do you suppose he loves us lunkheads and the hobby? My dad had two old Dooling .61s. one in a tether hydro and one in a beautiful Dooling tether car. He alway had spare rings. I'm going to get a couple extra for both of my ringed engines. Franks don't grow on trees.. In fact, due to word of mouth I may remove the ring on a new, never run engine and break it in with a Bowman ring. I'm buying my rings ungapped and go from there. My only problem is that I have a Mitutoyo dial vernier that measures my Craftsman feeler blades as being about .001" shy of what's etched on the blades. Do I trust Mitutoyo of Craftsman? Do I really care about .001" when my present end gap is .011"?[sm=spinnyeyes.gif] I'm going with Frank's recommendation. If he can make a ring he should be a good judge of what the end gap should be.

Bill

RE: Piston Ring End Gap
 

Not deglaze the surface in chromed sleeve... The chrome are very slippery and will not wear out the piston ring as the steel liner against piston ring. The piston ring are porous to take up oil inside and it has graphite inside as a part of the lubrication.

I has Moki M5 with chromed steel liner from 1973, there are no sign of worned surface in the liner. The engine has still original piston ring.

In your Enya and other engine of difference brands with steel liner (not chromed liner) need deglazed surface with wet/dry sandpaper 400-500 before use. It will improve the lubrication of piston ring with many pockets of oil in the cylinder surface and longer life of piston ring.

See my own made sleeve and piston/pistonring: http://www.rcuniverse.com/forum/fb.asp?m=4929500 :)

The Mitutoyo measure tools are of high quality. But the dial vernier/vernier caliper are not to rely.. accuracy of measurement when using a caliper is highly dependent on the skill of the operator. Regardless of type, a caliper's jaws must be forced into contact with the part being measured. As both part and caliper are always to some extent elastic, the amount of force used affects the indication. A consistent, firm touch is correct. Too much force results in an underindication as part and tool distort; too little force gives insufficient contact and an overindication. This is a greater problem with a caliper incorporating a wheel, which lends mechanical advantage. This is especially the case with digital calipers, calipers out of adjustment, or calipers with a poor quality beam.

To check the thickness at the feelerblade: use micrometer.

Use the feelerblade to measure the ring gap. If you has not less than 0.0019 (0,05 mm) which are common use in the feelerblade set. Buy the feelerblade set from machinist shop who are selling the feelerblade who are less than 0.0019 (0,05 mm), the feelerblade set are from 0.039 (0.1 mm) to 0.0007 (0.02 mm).


0.001 (0.0254) are not far away from where the ring gap in the Magnum 52 4 stroke engine who has a ring gap 0.0011 (0.03 mm) [8D]

RE: Piston Ring End Gap
 

There is no graphite, there is carbon but it is locked up between iron, moly, and other crystals.

RE: Piston Ring End Gap
 

See the link: http://en.wikipedia.org/wiki/Cast_iron , http://www.msm.cam.ac.uk/phase-trans...cast.iron.html

Edit: More new link..

RE: Piston Ring End Gap
 

Reading the Wikipedia article, it is not very complete as far as the full cast iron picture goes (irrevelent to our discussion), and the part about graphite was apparently written by a gentleman who English was not his first language, the factor of graphite itself is not disputed in the back page discussion.

RE: Piston Ring End Gap
 

Rings are not made from grey cast iron. More like malleable but with less carbon. If you made a ring from grey cast iron it would crack and break before you could get it on the piston. However, there are nodes of carbon, but would only be released when worn through and washed away quickly, not a significant factor.

RE: Piston Ring End Gap
 

While piston rings can be made from a variety of metals including steel, bronze, and variations of cast iron, the old accepted stand-by is regular old class 30 grey iron.

A friend sent me a Webra Heli engine after he had gotten the ring gap caught in the exhaust port. I lifted the end of the ring with a scribe and pulled the ring out with a pair of needle nose pliers. It came out like it was a paper clip??? Very soft? It didn't appear to have hurt the cylinder or piston so I put a new Bowman ring in it.

RE: Piston Ring End Gap
 

I have never seen a piston ring made from grey iron. Most are not grey at all but black (as is the surface color of nodular cast iron). Or when the cast surface is ground off they are shiny steel , without the gray color of grey cast iron. I suppose you could get away with this on a full size engine, but I don't think the rings would stay intact on our models. Pretty sure our rings are made from nodular meehanite. At least that is the material I would specify if I were the designer. It can be made to be maleable or soft (thus called maleable cast iron), but I think it should be hard but obviously flexable enough to install on the ring.