Chainsaw Repair

How To Basics - Carb Fixes + Mods - IPL and Service Manuals => How To Basics and Fixes => Topic started by: 660magnum on December 21, 2011, 01:49:45 pm

Title: Hard To Find Or Custom Piston Rings
Post by: 660magnum on December 21, 2011, 01:49:45 pm
Frank C Bowman of Farmington, NM has been making special and custom piston rings for years. He has a great reputation in the model airplane engine arena.

Some people remove the factory rings and install his rings.

You can even send your piston and cylinder to him and he will custom fit a ring to the assembly.

Rings are $11-$12 ea plus $4 1st class or $5.65 priority postage.

email: ringmaster46@msn.com Phone # (505) 327-0696 
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Cut4fun . on December 21, 2011, 01:53:05 pm
That sounds like a good deal. My last set of 181 thin rings were $40 and 2100 thin rings were the same price a couple years ago.

Hey snoopy make sure you check this thread out.
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 21, 2011, 07:23:35 pm
That's certainly reasonable enough .I have a set partly done for a Mac 125 made of A2 steel .They just need finished with a surface grinder .Before I got them completed I found a factory set for 14 bucks though .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on December 21, 2011, 09:18:54 pm
How does A2 work for rings? Were they hardened? Compare with the original Meehanite gray iron for rings? Other variations?

From one extreme to another?

I had to repair a European engine that the guy had caught the ring gap in the exhaust port at assembly. I was able to pull the previously run ring out of the piston grove through the exhaust port and it didn't break??? I figure he had originally got it too hot? The hard cylinder wasn't scored.

The Chinese ideology of a ring is that it be very hard. Most of the Chinese engines I see, you can run them for a year and the ring is still not fully seated all the way across the exhaust port.  Of course they are running in a "as cast" cylinder.
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Snoopy on December 21, 2011, 09:40:12 pm
Thanks for the info. I need some 181 and 2100 rings ;D
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 22, 2011, 05:26:14 am
I don't know how A2 would have worked because I never finished them .I just figured it was more stable than 4140 and should get hard all my itself kind of like gear steel . It was a pain in the butt to cut without over heating it .Fact I got a few so hard that carbide wouldn't cut them any more . I think I tried to get 6 but only ended up with three good ones .

The reason I used steel instead of cast iron is because the rings are so thin . I figured if I used iron that thin there would be a good chance of breaking them when installing .

On that praticular instance it was a Mac 125 that I resleeved with an iron liner .Grade 50 cast iron I think . Nodular would have been tougher but it doesn't cut like gray iron .

FWIW if you search the net you can find a zillion places that mention several methods of making rings .Interestingly  many are RC sites .Again though reiterating ,I've found more ideas from RC sites than I ever have from chainsaw sites .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on December 22, 2011, 10:24:54 am
I'm listening to you. I wanted to hear what you had to say.

I just never thought of making rings from it. But being air hard etc, I could see where it might be a viable alternative.

I always thought D2 machined real crisp. You can spot it a mile away because of the dull gray color. I suppose it would be just too brittle?

Seems like L6 rough and then go ahead and harden then draw it back would be hard but less chance of breaking? But I guess the rough finish before HT and then a final finish grinding would present a problem?

I noticed that a lot of things have changed in steels and cast irons in the last 30 years.
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 22, 2011, 01:17:13 pm
On some of the RC sites they speak about iron that once cut to size is placed on a mandrel and heated to set it on a slight expansion then cooled and tempered .You want some expansion but not too much from what I gather .

Then you have to hand lap the rings while under tension using a honing sleeve and fine lapping compound so it's pretty involved .That's what I say if that gent can turn out good rings for that price I wouldn't even fool around with them .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 22, 2011, 01:30:24 pm
Let me toss another tid bit of info which I found out the hard way .Don't use cutting oil in place of some type of coolant when cutting hard steel .The danged oil shields the part and drives the heat in  .Tool steel will get so hard the only way to cut it is with ceramic tooling which I have but most people don't .In addition the harder it gets the less machinabilty it has .

If nothing else give it a shot of water from a mist bottle .I myself can get water soluable coolant by the bucket full if I need  to for nothing .I just get a few ounces and mix it up as I need it which isn't that often .

Now you could use something like "tap Magic " which cools by evaporation but then you are breathing the fumes which I don't think is especially healthy . On occasion I have used WD -40 but I had a fan going at the time .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on December 22, 2011, 02:31:20 pm
I'm still listening

I remember having a W&S 4B with a hydraulic leak and couldn't get any production out of it at all with the hydraulic oil getting on the work piece.
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 22, 2011, 03:09:58 pm
 I might mention some of the British motorcycle sites have all kinds of tips for getting the most out of 2 cycle engines .Those guys will spend months lapping in and tweaking  say a Yamaha 250 from the late 60's and cranking out 50 percent more power than it had new .Strangley though they seem to have a time doing the same with a saw engine .

Then again if you think about it they have to adhere to a lot more regulations laws and edicts than we do so probabley that prevents them from much saw souping up . I'd bet though that if they could they'd turn out some dandys .Probabley a few do they just don't blab much on the internet about it . ;)
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on December 22, 2011, 04:10:58 pm
Most of the model airplane guys in Europe/Great Britain have noise limitations that many in the USA do not have to contend with.

Some in Western Europe seem to be able to do pretty good with the tuned pipes though




Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 27, 2011, 04:53:35 am
The tuned pipe thing is another one .Between the Brit MC sites and RC sites I've gotten more info than any and all locations dealing with saw  engines combined  ."top secret" I  guess .No big deal where  there's a will there's a way  .  ;)
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on December 27, 2011, 07:53:03 am
All the mods done to a chain saw like turning the edge (squish region) of the piston down to a minimum thickness above the ring and then taking the base of the cylinder or top of the crankcase down to make the squish be .020" were all things done to the Homelite 25 (weed whacker) R/C boat engines more than 20 years ago.

They were turning the fins off the cylinders and slipping a water jacket down over the cylinder.

These engines had cantilever cranks so the the rear of the crankcase was cut to place the plain back plate as close to the crank pin as possible, etc.

Some would change the cylinders by cutting off the original head and replacing with a new head to gain compression without moving the ports to far out of position.

The boat engines would be changed to run 15,000 instead of the 7000 they were designed for.
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 27, 2011, 06:55:05 pm
 ;D The thing about a small bore engine is the fact you don't have to be very far off with a die grinder to really screw it up . I little miscalculation can really  spell disaster .

I've never done any soup up work on a true RC sized engine .I can say though something tiny like a Stihl 200 or a Mini Mac is real tough to see what you're doing in a tiny blind hole .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on December 27, 2011, 07:24:27 pm
I never noticed any closed port cylinders under 45cc?

The Zenoah/Redmax 45, 62, and 80 twin are all open port.

The Chinese DLE 20 & 30cc cylinders have very generous open ports but the 50 & 55cc are closed port reed valve engines
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Troutfisher on December 27, 2011, 08:18:16 pm

real tough to see what you're doing in a tiny blind hole .

I haven't had that problem since college, but I don't think she was blind......just cross-eyed ;D
Title: Re: Hard To Find Or Custom Piston Rings
Post by: man of stihl on December 27, 2011, 08:38:37 pm

real tough to see what you're doing in a tiny blind hole .

I haven't had that problem since college, but I don't think she was blind......just cross-eyed ;D
That made me chuckle! ;D
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 28, 2011, 05:11:42 am
 :D Blind hole ,aye .

About the only closed port itty little engine I can think of is a Mini Mac .What like 2.1 cubic inch .There are made just about like the reed engines with welch plugs over the outside of the tunneled transfers except they only use 2 tunnels where a reeder uses 3 .

The engine wasn't a bad design it's just the rest of the saw is a POS .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on December 28, 2011, 07:43:19 am
I've got a Mini Mac that will run for a couple minutes. Someone gave it too me some 10 years ago.
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on December 28, 2011, 08:23:57 pm
Most times  it's the carb but you can't even find the rebuild kits for them any more .

With a mini there's only two kinds .Those that run  fairly well or those that don't run at all .More of the later than the former .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on January 01, 2012, 01:18:55 am
Dave Reed
OTTO GAS ENGINE WORKS 2167 Blue Ball Rd Elkton Maryland 21921-3330

phone: 410-398-7340
http://www.ringspacers.com/
http://www.ringspacers.com/ringcost.htm
http://www.ringspacers.com/piston.htm
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Cut4fun on February 15, 2015, 10:53:19 am
@man of stihl  maybe something in here.
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on February 15, 2015, 01:51:25 pm
If I need a ring and can not find a Cabor ring, I get them from this guy. If he doesn't already have them, you can send your cylinder and piston to him and he will make one to fit.

They are usually $15/set + the shipping back and forth

Frank Bowman 1211 N Allen Ave. Farmington, N.M. ... For Paypal payments use my email address,ringmaster46@msn.com or I can invoice you thru Paypal
Title: Re: Hard To Find Or Custom Piston Rings
Post by: man of stihl on February 15, 2015, 04:25:06 pm
Nice, thanks Jim
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Eccentric on February 15, 2015, 11:19:33 pm
Sweet.  Thanks Jim.  Do you know if he does the really thin rings (such as .062")?
Title: Re: Hard To Find Or Custom Piston Rings
Post by: 660magnum on February 15, 2015, 11:32:32 pm
He makes rings for model airplane engines and some of these are thin like you mention

This link brings up images but you can select the web at the top. Not all the images have to do with him. He doesn't wear a bikini. In the web mode there is his phone number? Might be old #? 505-327-0696

https://www.google.com/search?q=frank+bowman+rings&biw=1708&bih=764&source=lnms&tbm=isch&sa=X&ei=gXHhVM7ZF6rnsAST74CgAg&ved=0CAkQ_AUoBA&dpr=0.8
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Eccentric on February 15, 2015, 11:37:52 pm
So he doesn't play for the 49'ers either? 8)

(http://www.csnbayarea.com/sportsnetBayArea/thumbnails/Comcast_Sportsnet_Pacific_Associates/15/659/boldinMPX.jpg)

Thanks for the info Jim.  Hoping he goes above 2" for thin rings, as that'll make things much cheaper for the Homelite 750 guys.  NOS rings have been listed on feebay for $99/pair.  Crazy.  I'll call him about some rings for my Poulan 4000 too.  Those are thin rings that are getting scarce.  The 82cc McCulloch rings and thin SXL-925 rings are still plentiful for now.
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on February 17, 2015, 08:31:00 pm
Speaking of 82 cc Macs it seems at least on flea bay you can find a lot of
"b" pistons but"a"s are rare .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Al Smith on February 18, 2015, 05:03:41 pm
Something dawned on me at work today .On these bastard type rings it should be possible to use a sutface grinder with a magnetic table to shave a ring to thickness providing the rest of the ring fits .

Years a go ,fact close to 50 now I had an Indian Warrior motorcycle with bad rings .It was the same bore as I think an Indian 741.Rings for the 30.50 cubic vert. twins were almost non existant even back then but the V twin 741's were plentiful .Bought a set for 4-5  bucks and had a buddy grind them to thickess ,worked great .Possibley another way to skin a cat .
Title: Re: Hard To Find Or Custom Piston Rings
Post by: Cut4fun . on October 09, 2015, 06:45:45 pm
custom ring making bump here