From: earl@trsvax.tandy.com
Newsgroups: rec.models.rc
Subject: Re: Plugs
Date: 15 Dec 92 19:10:00 GMT
Nf-ID: #R:iex.uucp:11286:trsvax:1195667329:000:3867
Nf-From: trsvax.tandy.com!earl    Dec 15 13:10:00 1992



/* ---------- "Plugs" ---------- */
Well we are due for a new thread, so perhaps this will start one ;-)......
While flying my newly repaired Jensen Stick (Foam wing etc but that is another
story!) I had two episodes of the following. The first flight of the day was
quite nice. The plane has an older ST60 on it. I have been flying 5% Omega for
quite some time and Fox R/C Long plugs. First flight is in the 12 - 15 minute
range. After being down for awhile (meaning the engine was cool) I went up
again. 7 minutes into the flight and flame out. Bring her in and check the
engine. Not overly hot, doesn't seem too lean. Back to the pits. Check the
plumbing visually and everything seems ok. Try a third flight. Again a flame
out and back to the pits. Now with some help I reset the low end and top end
needle settings. They were off some. The plane had sat for awhile during it's
hospital stay so I guess with the weather being different it needed some
tweaking. So with the low end set to give a good transistion and the top end
leaving a nice vapor trail away I go again. Flame out at the 7 - 8 minute mark.
Got her in (this dead stick stuff is getting a little hard on the nerves by
now). So I pack it in and head home to replumb the tank, and clean the carb.
Next session 1st flight is fine. Second flight 7 minutes and flame out.
Multiple nasty words later I'm down and trying to figure out whats going on. A
suggestion was made to try a hotter/cooler plug. My replay is all I have are
R/C Longs. The suggestion is made to try a K&B with no idler bar. In it goes,
retweak low end and top end needle settings and now it flys like a champ! What
gives? Flew fine for over a year on R/C longs. Always on 5 or 10% fuel.
Typically Omega. Engine is probably 7 - 10 years old. I am the 4th or 5th
owner. Can anyone explain why things got better. The statement was also made
that this fellow NEVER uses plugs with idler bars in anything of a 60 size or
larger. But he left me no explanation as to why.
Thanks!
Doug
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'I am a traveler of                |    Douglas R. Jones
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**********************************************

    7-10 years old, sounds like your losing some compression, the cylinder to piston fit is probably getting loose. Sometimes, even the carburator gets worn and
starts to leak air too, plus the crankshaft is a bit looser and leaks air.
WHen the carb and crank is loose, then usually the engine starts to have trouble
drawing fuel. If the piston and ring have worn down, and the rod is getting
loose too, then you'll have less compression.
    If your engine runs better on 15% nitro based fuel then you know it's
    compression is getting weak.  If you have some 25% castor oil based fuel
    you could try it to see it it helps out on the compression too.

    Solutions?  Rebuild engine. Run higher percentages of nitro in the fuel.
	Increase the castor oil content to help boost compression. Run a
	hotter heat range glow plug. Maybe most of the above too.

***********************************************************************


<This information is provided by an individual and is not nor should be
 construed  as  being  provided  by  Radio  Shack or Tandy Corp.  Radio
 Shack/Tandy Corp has no obligation to support the information provided
 in  any way. > 
						
						Earl W. Bollinger
						@ <earl@trsvax>


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