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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › Blown a hole in my piston
11-13-2005 03:55 PM  12 years agoPost 1
F1 Carbon

rrApprentice

Perth, Scotland

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Just come home from blowing a hole in my OS 50 SXH piston after a year of flying and running it on Wildcat 5% with the MP11. Engine was in my Raptor 50.

As the temp dropped today to around 0-3 degrees I think the mixture ran a bit lean and before you know it bang a bit hole the size of a plug smack in the middle of the piston.

What doe you guys suggest ....repair or buy a new engine.

Or will Os consider compensation

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11-13-2005 04:05 PM  12 years agoPost 2
nivlek

rrProfessor

Norfolk England

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I had one go , got a new piston delivered in 5 days from CyberH for under £15 including delivery . The ring was OK , so I decided to re-use it , but a new ring isn't much dosh either .

At the end of the day , it gets dark .

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11-13-2005 04:07 PM  12 years agoPost 3
BarracudaHockey

rrMaster

Jacksonville FL

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What did you use to jam thie piston and install the fan. If the answer is a piston lock you probably dented it and weakened it.

If not then probably just an over lean run. I'd use it as an excuse to get a hyper.

Andy
AMA 77227
http://www.jaxrc.com

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11-13-2005 05:01 PM  12 years agoPost 4
nivlek

rrProfessor

Norfolk England

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Mine had actually failed on the side of the piston from half way down to the skirt . Either something got into the engine or there was a manufacturing fault . I only noticed when I had the engine out of the heli and was looking into the exhaust port , the engine had been running fine right up until it was removed to try a different engine .

At the end of the day , it gets dark .

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11-14-2005 08:13 PM  12 years agoPost 5
Penheliman

rrNovice

Leicestershire, UK

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Blown a hole in my piston
There was an instance of this exact same failure in a Richard Morris article RCHW about 12 months back. He blamed it on a lean run but I have had the same happen to one of my OS 50SXH's. It took 2 years flying to happen and has nothing to do with lean runs or fuel type or weather. The problem is that OS overthinned the piston crowns to lighten them and over-cooked the job. If you look at the milling inside the piston you will see it has drifted all over the place. I checked the thickness on mine (where it had not distorted) and it was thinner than 1mm in places. The repair was done FOC by Ripmax UK (for which I thank them) and the engine now runs fine.

I only wish I could get another of my OS 50SXH's to run the same. The carburettor is simply hopeless to get an even mixture throughout the operating range. I know several who have dumped the OS carb for a ST 60 aero and now get excellent running.

Penheliman

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11-14-2005 08:51 PM  12 years agoPost 6
BarracudaHockey

rrMaster

Jacksonville FL

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Have you tried the cats eye mod?

Andy
AMA 77227
http://www.jaxrc.com

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11-14-2005 10:21 PM  12 years agoPost 7
F1 Carbon

rrApprentice

Perth, Scotland

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I removed the piston tonight and have found no damage to the liner so the bits from the hole must have been ejected after failure. The top of the piston is what I can only describe as rusted with the hole the exact size of the plug.

I've sent off for a new piston and ring which I believe will be a lot less hassle than sending it back to Irvine.

As well as my raptor 50 packing in I had to auto in my Fury on Sunday as well which just had to land on a thick clump of reeds. It tipped the heli over resulting in the blades cutting the tail clean off. No other damage so I was sort of lucky as it could have been a lot worse.

Have to fly the mustang this weekend unless the parts come before Sunday.


BTW: whats the cats eye mod

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