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Blowing plugs after every flight 56LX engine

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Old 03-05-2011, 08:54 AM
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sudi9
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Default Blowing plugs after every flight 56LX engine

Hi !
I got a 56LX jett with about 4-5 flights on it,on a HANGAR 9 Jackal 50.

1. The first engine start was a real struggle, after i realiezed that no fuel was reaching into the engine, the original idle screw settings was almost shut al the way not enabling any fuel to th engine, after readjustments the engine came to life !!!

2. The engine is blowing plugs after every flight, i tried using several types of glow plug ,OS#10(cold), ENYA #3 hot, Rossi plugs, and the original that came with the engine(don't know the brand) all of them are blown after 5-6 minutes of flying.
I must say that the engine is running fine with no problems in the air and on the ground at full throttle, but just as you lower the throttle to idle during landing , the engine shuts off, and the plug is blown.

I am using a 5% nitro, with a non synthetic castor oil, a 9x9 prop with the original nut spinner,the fuel tank is foam isolated as well.
I tried two brands of fuels with no success.
What is the solution to this plug blowing problem ?
It's getting quite expensive ,replacing a glow plug after each flight ?
Thanks.
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Old 03-05-2011, 09:43 AM
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Default RE: Blowing plugs after every flight 56LX engine

I'll try to help.

I went through this with a SJ60LX.

1.Check ground rpm and fatten it up, drop it down about 800 rpm from peak. It is better to error on the rich side.

2. If this does not solve the problem. Remove it from the plane and set it up on a test stand. Adjust as neccessary. You could have fuel foaming in the air so dial it in on the ground and get it running right. Then if after flying if you pop plugs you are too lean (sucking air,foaming).

Jett engines turn high rpms and they need fuel to be there so leaning them out just over heats them and pops plugs. Remember when they are flying through the air the engine becomes unloaded at some point and rpm go up higher than ground rpms.

Hope this helps
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Old 03-05-2011, 10:20 PM
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sudi9
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Default RE: Blowing plugs after every flight 56LX engine

Thanks Dambo,
I will recheck for air in the fuel, although i did isolate the fuel tank, and checked it for air sucking and could't find any problems with it.
This is my first Jett engine, i am not familiar with such problems on other brands of engines that i have been using (OS, Rossi).
What about using 5% nitro fuel ?
Should i try 10 % ?
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Old 03-05-2011, 10:21 PM
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Default RE: Blowing plugs after every flight 56LX engine

Thanks Dambo,
I will recheck for air in the fuel, although i did isolate the fuel tank, and checked it for air sucking and could't find any problems with it.
This is my first Jett engine, i am not familiar with such problems on other brands of engines that i have been using (OS, Rossi).
What about using 5% nitro fuel ?
Should i try 10 % ?
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Old 03-06-2011, 06:54 AM
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Default RE: Blowing plugs after every flight 56LX engine


ORIGINAL: sudi9

Thanks Dambo,
I will recheck for air in the fuel, although i did isolate the fuel tank, and checked it for air sucking and could't find any problems with it.
This is my first Jett engine, i am not familiar with such problems on other brands of engines that i have been using (OS, Rossi).
What about using 5% nitro fuel ?
Should i try 10 % ?

Are you using the Jett stream muffler or full tuned pipe on this engine?
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Old 03-06-2011, 11:20 AM
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bob27s
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Default RE: Blowing plugs after every flight 56LX engine

Thanks for writing........

Blowing plugs is caused by a lean run 90% of the time.

MOST of the time it is because of a fuel system issue.

Make sure the fuel tank is not touching the airframe at any location (ANY location) and is padded all around. The energy the 56L puts out is far beyond any other engine. Any opportunity to creat fuel foam will cause it to form.

As was noted, you want to back off of ground peak rpm 800-1000 rpm for launch. When in flight the engine will unload, and needs the additional fuel.

Good advice provided. Put the engine back on the test stand. Observe how it runs, where that 800-1000 needles setting is. Then put it back in the plane. If it does not behave the same - goes lean - you know the problem lies within the aircraft.

Bob
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