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Author Topic: rings ??  (Read 1225 times)

Offline Alan Buck

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rings ??
« on: July 18, 2010, 03:00:24 PM »
How do you tell if the ring is bad. I have little power,poor starting, needle setting does not help motor acts like it is rich when needled in. The motor is a Super tigre 51 made in china. NO I will not stop using them. Thanks, ALAN
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Offline Robert Zambelli

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Re: rings ??
« Reply #1 on: July 18, 2010, 03:12:33 PM »
Alan - disassemble the engine and examine the ring. It should protrude slightly from the groove. That is, it will pop out of the groove when it clears the sleeve.
Carefully remove the ring from the piston and intall it back into the cylinder, using the piston to push it in and keep it perpendicular to the bore.
Measure the end gap at various locations along the bore. It is usually tightest at TDC - around .001".
If you have any doubts as to the procedure and measurements, send the piston and sleeve to Frank Bowman. He will make a new ring and custom fit it to the cylinder.
His work is the best I've seen.

Bob Z.
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Online Brett Buck

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Re: rings ??
« Reply #2 on: July 18, 2010, 03:14:22 PM »
Quote from: Alan Buck on July 18, 2010, 03:00:24 PM
How do you tell if the ring is bad. I have little power,poor starting, needle setting does not help motor acts like it is rich when needled in. The motor is a Super tigre 51 made in china. NO I will not stop using them. Thanks, ALAN

    I don't know for sure for the 51, but for the 46, if you have much more compression in one direction than other, thats a good sign. Reduced power and increased fuel consumption also used to be good indicators - along with a lot of the things you mention (most of which could have other causes, too). Hence the endless fiddling we used to do with ST46s and the like.

      Brett

  
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Offline Robert Zambelli

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Re: rings ??
« Reply #3 on: July 18, 2010, 05:06:03 PM »
Alan - look in the vendors corner of Stunthanger - you'll find Frank Bowman's info.

Bob Z.
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Offline Alan Buck

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Re: rings ??
« Reply #4 on: July 18, 2010, 06:13:13 PM »
Bob and Brett, Thanks for your answers. It does have more compression one way over the other. fuel consumption about the same. No scores in clynder or other marks. will get new ring from Frank thanks
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Offline Steve Fitton

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Re: rings ??
« Reply #5 on: July 21, 2010, 01:19:05 PM »
Hey Alan, did you get a chance to test the plane on the other known to be good motor yet?
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Offline Bill Little

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Re: rings ??
« Reply #6 on: July 21, 2010, 06:53:04 PM »
HI Alan,

I would definitely suggest the Bowman ring.  Seems the Chinese built G-51 are all over the place with quality control, unlike the Italian made ones.  And the factory ring is no where near Frank's quality, either.  His are much more durable, and better machined.  Tom Lay uses Frank's rings in everything he does.

Bill
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Offline Gene O'Keefe

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Re: rings ??
« Reply #7 on: July 22, 2010, 07:54:17 AM »
I thought Frank wasn't working on engines anymore - if he is, his work impeccable. If you want more grunt out of your .51, send it to Tom Lay to rework. He will hardened insides & use a Bowman ring & you will have a more powerful .51 than before ( I have two .51's from him and they are much much much better then stock.

 Geno
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Offline dennis lipsett

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Re: rings ??
« Reply #8 on: July 22, 2010, 10:51:28 AM »
Quote from: Bill Little on July 21, 2010, 06:53:04 PM
HI Alan,

I would definitely suggest the Bowman ring.  Seems the Chinese built G-51 are all over the place with quality control, unlike the Italian made ones.  And the factory ring is no where near Frank's quality, either.  His are much more durable, and better machined.  Tom Lay uses Frank's rings in everything he does.

Bill

Bill,
since I have quite a few Italian and Chinese Supertigres I'll throw this out. The italians didn't have any better rings then are on the Chinese versions. I'm easily amused by people wanting to buy only an Italiin version or the seller proudly claiming the same. Run them both and I doubt that you will see any difference.
But by all means I like modified engines too and Frank Bowmans ring is probably the most sensible upgrade you can do.
Dennis
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Online Brett Buck

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Re: rings ??
« Reply #9 on: July 22, 2010, 01:22:55 PM »
Quote from: dennis lipsett on July 22, 2010, 10:51:28 AM
since I have quite a few Italian and Chinese Supertigres I'll throw this out. The italians didn't have any better rings then are on the Chinese versions. I'm easily amused by people wanting to buy only an Italiin version or the seller proudly claiming the same. Run them both and I doubt that you will see any difference.
But by all means I like modified engines too and Frank Bowmans ring is probably the most sensible upgrade you can do.

  I agree.  I don't have any ST51s,  and I don't have any information about Chinese VS Italian but to say that the Italian QC is any sort of reference standard to aspire to is pushing it. I never had two identical ST46s in either design or assembly, and towards the end (80's) the rings were widely variable in a range from "very poor" to " unusable". The quality control was light-years ahead of Fox, but compare it to another contemporary engine, the OS40VF, all of which were essentially identical and you can come up with a completely repeatable setup that you can get working over the internet.

    Brett
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Offline RandySmith

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Re: rings ??
« Reply #10 on: July 22, 2010, 02:46:38 PM »
I have actually setup over a 100  ST 51s many of the Chinese versions, There has nothing O have seen that makes me think one is superoir to the other, The stock rings I have seen from China are as good as any I have seen from Italy. I have had to replace a few in both but not many. I have also had a very few that where broke/chipped in new engines. Rings have to be set properly and ran in properly no matter who makes them or where they come from.
You CAN DESTROY any new ring with one lean run when they are new very easy.

Randy
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Offline Martin Quartim

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Re: rings ??
« Reply #11 on: July 22, 2010, 04:24:34 PM »

Randy your know how about engines surpass any one I know and you have many years experience. But what you are saying is not what I have found rebuilding a few ST G51s. The Chinese ones I worked on had poor quality pistons with many casting flaws, the Italians ones had very smooth and solid look, like I see from Enya and OS.

Probably the Chinese factory have much superior CNC machinery then when it was made in Italy, however I question if the metalurgy of the Chinese ST G51 are as solid as the Italian ones.

Lately I have seen many people having trouble with ST G51, so I must believe their quality control is not that great. Many times replacing the ring fixes the problem, but in some cases even with a good ring it does not work well. That makes me wonder if these mysterious problems are not related to the metalurgy of the engine, specially the piston,  as far as expanding and retracting due to heat cycle during flight.

Martin
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Offline RandySmith

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Re: rings ??
« Reply #12 on: July 22, 2010, 07:56:02 PM »
Quote from: Martin Quartim on July 22, 2010, 04:24:34 PM
Randy your know how about engines surpass any one I know and you have many years experience. But what you are saying is not what I have found rebuilding a few ST G51s. The Chinese ones I worked on had poor quality pistons with many casting flaws, the Italians ones had very smooth and solid look, like I see from Enya and OS.

Probably the Chinese factory have much superior CNC machinery then when it was made in Italy, however I question if the metalurgy of the Chinese ST G51 are as solid as the Italian ones.

Lately I have seen many people having trouble with ST G51, so I must believe their quality control is not that great. Many times replacing the ring fixes the problem, but in some cases even with a good ring it does not work well. That makes me wonder if these mysterious problems are not related to the metalurgy of the engine, specially the piston,  as far as expanding and retracting due to heat cycle during flight.

Martin



Hi Martin

I have seen both versions with casting flaws in the case and in the piston, however that has not been normal, The Italian and China version flaws are about equal,I have only seen that in about 6 motors. and I have had not problems with the parts I get from them for rebuild. I do not though use the bearings for rebuild. I have very good bearings here. The Sleeves in both versions need to be honed or chromed before use in rebuilding ..if.. they have had a lot of runs on them, or just replce with a new sleeve. The rings MUST  be carefully gapped also

Randy
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