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Ring installation
Guys, need some help. I did a search but could not find a post for this question probably because everyone already knows the answer.
I'm replacing a ring in a G75, I got the old ring off, but broke it. So now I'm concerned that I'll break the new ring when trying to get it on the piston. Can someone tell me the best method for actually putting the ring on the piston? Do you "spiral" it on or do you open it enough to slip it over all at once? or use some other method? Thanks for the help; this is a new experience for me. |
RE: Ring installation
Spiral it on
Lay ring on top of piston bring one side at gap down the side of piston towards groove With that one end of gap in groove rub the rest of the ring in a circle around the piston and the whole ring will jump in the groove |
RE: Ring installation
W8YE gave you, in my opinion, the best system.
I would only add to clean the grove of your piston using one of the old ring broken pieces. By scraping the piston grove from oil and other residues, you will guarrantee that the new ring will seat properly on its grove. Good luck! |
RE: Ring installation
Thanks for the instructions, I'm sure with your help everything will go smoothly
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RE: Ring installation
The G75 has a pinned ring. The pin is inside the ring groove. Find it.
That's where the ring gap goes |
RE: Ring installation
the pin fits inside the groove (or little cutout) in the ring right? not the gap between the ring ends?
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RE: Ring installation
Correct
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RE: Ring installation
So I got the ring in no problem, put the eninge back together and STILL had very poor compression. At least it only cost me 10 bucks for the ring. I dropped some motor oil in the cyclinder and then it had descent compression.
With just some fuel in it, I could turn the shaft by hand and have some resistance but it would all bleed off at the TDC in about 3 seconds, new ring didn't seem to help even through it is contacting the cyclinder wall adequately (at least I think so), So now I'm guessing either the cyclinder is warped, or its normal. I'm not spending any more money on this engines so I sure hope its normal because if its performance doesn't get better, I'm going to be buying a different brand, maybe a thunder tiger 90 or something. |
RE: Ring installation
That is perfectly normal...
the ring must be seated in the cylinder, it muss take the perfect shape of the cylinder...in other words, you have to break in the engine again! Just put some fuel on it and let it run Saludos, Jorge |
RE: Ring installation
Usually when people put a new ring, also do a Honing of the cylinder walls...
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RE: Ring installation
estradajae gives good advice to hone the cylinder wall. You can 'hone' it with sandpaper on your finger. Unless the finger is too fat.
Also a drop or two of oil on the ring through the exhaust port to help make a seal and the felt compression will be more. Terry in LP |
RE: Ring installation
ORIGINAL: flhyr So I got the ring in no problem, put the eninge back together and STILL had very poor compression. At least it only cost me 10 bucks for the ring. I dropped some motor oil in the cyclinder and then it had descent compression. With just some fuel in it, I could turn the shaft by hand and have some resistance but it would all bleed off at the TDC in about 3 seconds, new ring didn't seem to help even through it is contacting the cyclinder wall adequately (at least I think so), So now I'm guessing either the cyclinder is warped, or its normal. I'm not spending any more money on this engines so I sure hope its normal because if its performance doesn't get better, I'm going to be buying a different brand, maybe a thunder tiger 90 or something. Run that puppy some and the compression will come up. A guy gave me an Kraft 61 engine once because it had almost no compression. Apparently he had disassembled the engine and disturbed the ring. I ran the engine about a half hour and compression was normal. |
RE: Ring installation
ORIGINAL: masama1107 W8YE gave you, in my opinion, the best system. I would only add to clean the grove of your piston using one of the old ring broken pieces. By scraping the piston grove from oil and other residues, you will guarrantee that the new ring will seat properly on its grove. Good luck! |
RE: Ring installation
Thanks guys, I'll re-break it in and I'm sure that will bring the compression to where it ought to be.
Thanks! |
RE: Ring installation
Thw way I install a piston ring is to hold it right over the top of piston. I catch both end-gaps with my thumb-nails and spread the gap just big enough for ring to slip onto piston. I have not broke one yet!!! Capt,n
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RE: Ring installation
Ok, so I got the ring in, and put 40 oz through the engine, and the thing is still a dog with very little copression. so little still in fact that sometimes when you start it by hand it won't even pop through all the way around, but stop at TDC.
The engine had a lean run in the air where the eninge shut off, and I'm guessing that did more damange than just to the ring. Right now it will spin a 12-6 K-series MAS at only 11700, My buddies 55 ax spins that, so I'm guessing this thing is toast. |
RE: Ring installation
ORIGINAL: flhyr the pin fits inside the groove (or little cutout) in the ring right? not the gap between the ring ends? If the pin is positioned underneath any part of the ring, the ring will be pushed up and held out-of-round, and will not form a proper compression seal. Does the SuperTigre have a different arrangement? |
RE: Ring installation
*
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RE: Ring installation
ORIGINAL: flhyr Ok, so I got the ring in, and put 40 oz through the engine, and the thing is still a dog with very little copression. so little still in fact that sometimes when you start it by hand it won't even pop through all the way around, but stop at TDC. The engine had a lean run in the air where the eninge shut off, and I'm guessing that did more damange than just to the ring. Right now it will spin a 12-6 K-series MAS at only 11700, My buddies 55 ax spins that, so I'm guessing this thing is toast. |
RE: Ring installation
ORIGINAL: gyrocptr ORIGINAL: flhyr the pin fits inside the groove (or little cutout) in the ring right? not the gap between the ring ends? If the pin is positioned underneath any part of the ring, the ring will be pushed up and held out-of-round, and will not form a proper compression seal. Does the SuperTigre have a different arrangement? |
RE: Ring installation
1 Attachment(s)
I believe these photos can clear up the issue...
The one with the separate notch for the pin and 'square-cut' ends, is a Super Tigre piston ring. The other, with the notch within the ring-gap, is from an OS. |
RE: Ring installation
ORIGINAL: flhyr Ok, so I got the ring in, and put 40 oz through the engine, and the thing is still a dog with very little copression. so little still in fact that sometimes when you start it by hand it won't even pop through all the way around, but stop at TDC. The engine had a lean run in the air where the eninge shut off, and I'm guessing that did more damange than just to the ring. Right now it will spin a 12-6 K-series MAS at only 11700, My buddies 55 ax spins that, so I'm guessing this thing is toast. |
RE: Ring installation
1 Attachment(s)
ORIGINAL: captinjohn The piston ring may have lost its tension from lean run. Put in a new ring from Frank Bowman and it will sing again! This may be true, but the ring's tension ('springing' out against the cylinder) is a very small contributor to sealing and thus to engine power. The 'large' force that contributes to the ring seal, is high-pressure gas from compression/combustion, getting into the ring's groove and pushing the ring 'from behind', against the cylinder wall. See the drawing. It is for a Dykes ring, but a normal ring seals similarly. Low ring tension will, however, reduce sealing during cranking, making starting a more tedious endeavor... |
RE: Ring installation
W8ye, Can you tell me what I should expect from this engine on a 12-6 or even a 13-5?
I flew the plane yesterday with a 13-5 and it had descent power, but not enough to really have fun with. Its in a 3d plane and had enough power to hover, but only with 3 clicks to spare. I also had 3 or 4 flame outs at low throttle, but towards the end of the day it seemed to be okay, but still not right. Should I be expecting 12K on the 13-5? |
RE: Ring installation
It should be more in the high elevens with a 13 X 5
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