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GrandRC . CanoMod . Futaba-RC

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Engines Plugs Mufflers Fuel > Problem going from 15% to 30%CP
 
 
webman
Heliman
Location: Metamora, MI

Why is this such a headache?

Have an OS61SXH which was broken in with and running great with 15%CP. Now that I'm starting some 3D stuff with my Freya, the extra power from 30% is something I'd like to have. So I richened up the needles a little and put in the 30%. What the engine does is make this intermitent metalic sound in sync with a little tail wag to the left (RPM must drop). I can stop it by leaning the engine out, but must lean it to the point of losing most of my smoke trail - engine also loses much of it's upward acceleration after a minute or so (sure sign of too lean?).

Any ideas? Will it settle down (5 tanks of 30% are through it) or will I have to give up and stick with the 15%????

Needles settings are at: H 1 1/4, M 1/2, L 1 1/2
07-25-2002 Over year old.
HOMEPAGE  
 
 
NEM3
Veteran
Location: New Lenox, Il

Mind you I have never had a 60 size heli but it sounds like your engine is preigniting. That is were the pinging is coming from.

Most of the time the preingition can be stopped by adding a head shim. I don't know if you can do that with the O.S. 61 as my O.S. 50 already had a head shim installed.
07-25-2002 Over year old.
 
 
Roamer
Veteran
Location: Albuquerque, NM

Nem3 hit it right on the head. It really sounds like your engine needs an extra head shim to get the compression right for the higher nitro fuel. I would guess that you fly at lower altitudes?
07-27-2002 Over year old.
 
 
Conrod
Veteran
Location: Melbourne, Florida

I agree with David H.

I couldn't get mine to run on 15% until I pulled the headshim.
Richen that baby up and make sure you have a shim.
conrod
07-28-2002 Over year old.
 
 
davehour
Key Veteran
Location: Guayama, Puerto Rico

I'm having the same problem as you. I have richened and leaned it (midrange and high) and the interference is never gone. I'm using the Muscle pipe.

My settins are H= 1.4, M= .4 and L=1.5 turns.
07-28-2002 Over year old.
 
 
charly
Heliman
Location: xenia, ohio

Sorry to barge in, but my os50 run like crap on 15%...can I take out the shim without messing anything up?

charly
07-28-2002 Over year old.
 
 
webman
Heliman
Location: Metamora, MI

Gave up on the 30% (for now). Have experimented with a half and half mixture of 15% and 30% (funky color). Much better but the engine still sound a little tinny - will do for now. Had the LHS order some of the new CP20% to see how that might work out.

Low end needle is open 2 turns - pinch test after landing is about 2 seconds for a rev up and another 5 seconds for it to die. High end needle was adjusted (with the mid closed) to 1 1/4 turn out - just the point that the heli rises with some authority - bottom of cooling fin can be touched firmly for a second (no more!) after landing. Mid needle is out 3/4 turn - the point that gives a smooth hover.

Would still like to pursue the 30% - is it possible that an OS61 purchased new last year would be missing that shim? Where on the engine would it be?
07-28-2002 Over year old.
HOMEPAGE  
 
 
webman
Heliman
Location: Metamora, MI

It's an Enya #3 with a Zimmerman muffler. Thought of trying an OS #8 (isn't it a cooler plug?) . Then again, must be more than a couple pilots out there flying a OS61/Zimmerman/Enya #3 combination and loving it - so I'm pretty much at a loss here.
07-28-2002 Over year old.
HOMEPAGE  
 
 
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Engines Plugs Mufflers Fuel > Problem going from 15% to 30%CP
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