[NSRCA-discussion] OS 140RX rough and inconsistent idle

[Keith Hoard]

I'll second that. . . . check your bearings and put in a set of stainless. .
.

On 6/26/06, mwaustin54 at cox.net <mwaustin54 at cox.net> wrote:
>
> You might check your bearings. My OS 140 did this after 50 or so flights.
> New bearings solved the problem. I also run the Mentor head and like the
> transition.
>
> Mike A.
> ---- Ed Miller <edbon85 at charter.net> wrote:
> > Have an OS 140RX that has developed a rough and inconsistent idle.
> Engine
> > runs perfectly except for idle. It has a Mintor head with either an OS F
> or
> > K&B 1L in center plug and an OS A5 in the angled plug position, a Perf
> Spec
> > AAC piston/liner assembly and a Boca sealed SS rear bearing. I have the
> head
> > mounted with angled plug towards the front or carb side of engine. Fuel
> is
> > S&W 20 nitro, 16 synthetic and 2 castor. Engine has 7 gallons of fuel
> run
> > through it. Prop is an APC 15.75 x 11 3 blade by Dave Lockhart.  The
> lowest
> > I can get the idle before it quits is 1900 ~ 2000 rpm and it is rough,
> > sounds like it is firing every other revolution. Idle mixture screw is
> > working, I can richen idle to point where engine will barely transition
> from
> > being rich and I can lean mixture so the transition is fine but engine
> slows
> > at idle like it is too rich. While it is slowing with either the idle
> > mixture screw lean or rich, engine is rough, again like it often fires
> every
> > other revolution at times. I used to be able to reliably idle this
> engine at
> > 1300 rpm. I have a second OS 140RX set up exactly the same except it
> doesn't
> > have the AAC piston/liner and it runs/idles perfectly. Tried cleaning
> the
> > carb/spray bar with no change. I once had a Super Tiger that exhibited
> > similar characteristics due to a worn out con rod.  Is it possible the
> con
> > rod on this OS could cause this issue ?? Any suggestions will be greatly
> > appreciated.
> > Ed M.
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>
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-- 

Keith Hoard
Collierville, TN
khoard at gmail.com
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