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HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › Some engine issues(O.S. 50 Hyper)/ Updated
07-30-2007 09:35 PM  13 years ago
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ckoelliker

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Some engine issues(O.S. 50 Hyper)/ Updated
My engine seemed a bit sluggish this weekend, so I decided to take it out and have a look. I found three problems. One is that it is leaking some where. I think it is at the muffler, but I am not 100% sure. The piston ring had a small shiny spot on the exhaust port side. Under the ring the piston was also shiny with that "drip like" extension of the wear. The liner looked fine. It only seemed discolored where it matched up with the piston. Also my back plate had some scratches. I think my fan must of slightly slipped. Anyway I have some pictures, but knowing my camera they will not be that good.

I guess I am asking, if I should replace the ring, the piston, or just leave it as it is?

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07-30-2007 09:36 PM  13 years ago
ckoelliker

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Well I was right about one thing. My camera sucks. Just try to use your imagination. Thanks.

Edited: I have some more pics. Maybe these will be better

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07-31-2007 12:31 AM  13 years ago
airdodger

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You had the engine too hot the burned oil on the piston top and the quick stick on the exhaust port show that. You need to be sure no aluminum from the piston is on the liner. I would get a new piston and ring, and find out why the rod was hitting the backplate. Remember the metal rubbed off went somewhere maybe on a bearing race, so I would change the rear bearing at least and clean the engine throughly. Fix the leak that may have been the source of the problem.Chris
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07-31-2007 12:39 AM  13 years ago
ckoelliker

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I think my fan slipped. It has a tiny bit of wiggle. The liner looked fine, but how do I tell if it has aluminum on it? What is a "quick stick"?
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07-31-2007 12:49 AM  13 years ago
airdodger

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Quick stick, when the engine deposits a small trace of aluminum on the liner and does not completly seize, or in your case the exhaust bridge expanded and rubbed on the piston. The aluminum should be visible on the liner, use a bright light.Chris
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07-31-2007 01:44 AM  13 years ago
ckoelliker

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If it is there, what then?
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08-01-2007 09:58 AM  13 years ago
Barney

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Inverness Scotland

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If the muffler came loose at all it will give you a lean run..same as a leaking pressure line etc etc same result.

The scratch marks on the backplate are normally caused by the rear bearing going South...also motor will be down on power...poss a slight knock at idle depending on severity.
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08-01-2007 03:17 PM  13 years ago
ckoelliker

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The bearings are fine. I changed those about two months back. I think the lean runs were before that bearing change.At that time, I just did not notice the ring or the wear on the piston. All in all the engine ran fine. It idled smoothly, started easily, and seemed to hold a consistent temperature. Either way I checked the bearings and they are fine. These are stainless bearings that came with an engine that I had bought used a while back. On a side note I really like how the bearings are holding up. I have had a lot of problems with rusting. I have tried all sorts of ways to store my engines, but I think the south Georgia humidity is just going to win that battle. But the stainless bearings looked great.
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08-05-2007 11:59 PM  13 years ago
ckoelliker

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Well I rebuilt everything with a new piston and ring. I fixed the leak, which was the muffler, and replaced all the fuel line. It started up great and idled smoothly, but it still does not have the power. It is like it is running at 1800 when it should be 2000. I just dropped the motor again, took everything apart, and cannot find the problem. The bearings look fine. I took the carburetor apart and could not find any sort of problem. Maybe my liner is shot, but if that is the case, I cannot visually see any problems. I did notice that it was dripping a little bit of unburnt fuel out of the muffler when it was running. I always thought that that meant that it was running rich. So maybe I have not fully seated the ring, but I do not think so. Any thoughts? The ring did not have shiny spots on it, but I could see where it was lighter around the pin and the same place that lines up between the exhaust ports. Should I be able to see a difference in the color of the ring, or should it be exactly uniform all the way around?
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08-06-2007 12:52 PM  13 years ago
Barney

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Inverness Scotland

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Although the ring may look fine it may have lost it's springiness.

Unless you have a brand new ring to compare it with you will not be able to test for this.

A ring replacement usually rejuvinates a well used or cooked motor providing there is no other damage to the motor. The liners are usually very hard wearing. I have one Hyper 50 here thats had over 100 gallons on it and only requireed one new ring + conrod and a few sets of bearings. This motor still outperforms my two newer hyper 50's! I generally run it around 18000-18250 so it has not had a sissies life.

I realise you cooked your motor, but is there another problem?

While your at it change all your fuel lines etc.

A partially blocked muffler will also hold the motor back causing you to overlean it trying to get power.

Also check carefully the idle cam is seated correctly in its slot..this is easily missed and that the barrel servo arm screw is tight.

Check the throttle servo for full and smooth travel.

Try some quality fresh fuel to eliminate that & fit a new OS8/Enya no 3.

Settings around 1-1/2 turns out on the main & the idle moved from the 12.00 to 1 o'clock position to. Then check the temp on backplate with your finger after spooling down..warm is good but not hot
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08-06-2007 09:40 PM  13 years ago
airdodger

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Johnston USA

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Did you really put the same ring back?Chris
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08-06-2007 11:13 PM  13 years ago
Barney

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I bought this motor used with around 10 gallons through it and fitted new bearings as a precaution...went 300+ flights before needing bearings ( I wish the bearings all lasted like that set)

10 gallons on and I cooked it..burst pressure line in flight. I checked it out and it seemed reasonable for the running it had done so just cleaned the internals and fitted new bearings..It then ran fine but I was going through bearings every 2-3 gallons..

At about 60 gallons enough was enough so I got bought a new motor..
This newer motor has never really performed as the good as the old one . and was using bearings in a similiar fasion..first set at 2 gallons

The old motor on closer inspection had a partially seized Gudgeon pin in the conrod and the ring had visible wear (slightly oval). Anyways I cleaned it all up and went flying but still not brilliant for obvious reasons. At close on 70 gallons I planted it in concrete from 80' broke the crankcase, head, bent crank..

At this point I was still going through bearings steadily in both motors (bad batch of bearings or fuel related I think)

I robbed the newer motor for the head, crank case & crank and rebuilt it using the originial piston, liner, and carb from No 1 and also fitted a new conrod and ring as it was suffering from obvious blow back on the sides of the piston..new bearings from SMB (Not the OS items..£7 )

Well I've not looked back..it's back to being a little screamer and fast approaching the 100 gallon mark..

Phew what a screed!
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08-06-2007 11:24 PM  13 years ago
ckoelliker

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I did replace the ring. And the fuel tubing. The new ring already had a slight discoloration at the same spot between the two exhaust ports. It is not shiny, but just a little bit lighter than the rest of the ring. I do have another unused ring. I ordered two of them last week. How can I tell if it is still "springy"
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08-06-2007 11:34 PM  13 years ago
airdodger

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Johnston USA

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It should take some pressure to place ring in the liner without being on the piston, it will also have a large gap when just sitting there. You could have warped the exhaust bridge too.Chris
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08-06-2007 11:58 PM  13 years ago
ckoelliker

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It still seems to have compression. I put it back together last night(again), but I have not flown it yet. So I do not know if it was something I did while assembling. How can I tell if I have warped the liner. Is it something I would be able to see?
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08-07-2007 01:15 AM  13 years ago
airdodger

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Not warped the liner just the bridge. No I doubt you could tell without a boregage.Chris
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