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<DIV>NOPE, you're not gonna get me!! I don't do longwinded stuff, not even my
own. This might be first chapter of your Thesis tho. (BG)</DIV>
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<DIV>Matt</DIV>
<DIV> </DIV>
<DIV>In a message dated 3/1/2006 7:39:43 PM Eastern Standard Time,
dflynt@verizon.net writes:</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 size=2>Today
was one of those beautiful California days, in between the rain, and I<BR>have
the week off, so I finally got my ZNline Supreme in the air for
several<BR>trim flights. Also, I switched from the Webra 160 with M/C to
the OS 140RX.<BR>Below are my initial impression of OS, along with comparison
to YS 140DZ:<BR><BR>I was particularly careful while breaking in the OS.
I wanted to ensure no<BR>problems, and the engine was ready for fly
time. I broke in on the bench<BR>with one gallon of fuel. I saw
7800 rpm with a 16.5x12w prop mounted in the<BR>plane today, fairly
rich. I'm hoping I have it set way too rich, and that<BR>it will gain
more power as I get more fuel through it. My setup is a Karl<BR>Mueller
header at 9 3/8 inches from from exhaust flange to the entrance of<BR>the
pipe, and an ES 2C140M80 muffler. Cool Power 15%. The Mueller
header<BR>has a sharper rise over the OS or Hatori header, and I needed that
to clear<BR>my firewall. Total length due to the sharper rise is near
the same as the<BR>stock OS header. What a nice header BTW. It has
the right thrust built in<BR>so it is straight down the middle of the pipe
tunnel. It came with a short<BR>extension so that there is stress relief
on the header to prevent it from<BR>breaking.<BR><BR>Big two strokes are new
to me. Before this engine, I was running a YS<BR>140DZ, and before that,
YS 120 - 140. Here are my initial observations and<BR>comparison between
the 140DZ and 140RX:<BR><BR>Ease of use: Probably a toss up. The
OS is very user friendly, and is<BR>simple, and runs on sport fuel. It
is not as easy as the YS in that you<BR>need to tune header length and select
optimal prop and muffler/pipe, however<BR>for the OS you can stand on somebody
else's shoulders, and that is what I<BR>did for the most part. I don't
know if I am done tuning it however. Both<BR>engines are pretty much
hands off once broken in and set (at least what I<BR>hear for the OS). I
flew 300 times with the DZ, and never touched the<BR>settings after break
in.<BR><BR>Ease of start: Hands down, OS. This engine starts with
ease. The DZ, once<BR>you learn it, will start easy so long as you have
a strong starter and<BR>strong glow source. But it can lock up on you if
you allow it to flood.<BR><BR>Idle: Definately the OS. I had a
good idle after one gallon, and I still<BR>have not touched the low end from
factory setting. The YS will idle ok for<BR>a while once warmed up, but
it won't idle forever. It does not really<BR>matter so long as you do
not let it idle for long periods.<BR><BR>Reliability: No way to know
since I don't have time on the OS, but one<BR>strike against it today.
It flamed out at the bottom of the reverse<BR>avalanche. I just made it
back, heart pounding all the way. This is<BR>probably an anomaly, and I
only have 1 1/2 gallons through it (I should not<BR>have been practicing the
reverse av with such little time on the engine, but<BR>oh well). Idle
speed was 2000 on the ground. On the first flight however,<BR>I overshot
the runway twice, and I had to go around. So, it stayed lit when<BR>it
counted. The DZ never flamed out during flight. I speculate that
the DZ<BR>is more reliable, but I am splitting hairs.<BR><BR>Quietness in the
air: OS is quieter, like a whisper compared to the DZ. DZ<BR>has a
lower pitched noise.<BR><BR>Vibration: OS is much less vibration and
very smooth at idle through full<BR>thottle. There is an area about 1/4
throttle where it shakes a little, but<BR>not bad compared to the DZ.
The 160DZ I hear is a lot smooother than the<BR>140DZ, which would be
nice.<BR><BR>Torque: Hands down, the DZ. The DZ has a smooth,
linear throttle curve and<BR>usable torque at any throttle setting. This
is what is so great about the<BR>DZ. The OS is fairly limp and useless
until you get past 1/3 throttle. At<BR>half throttle it comes alive, and
at 5/8 throttle to full throttle, there is<BR>little difference in
output. I think this is one of the major differences<BR>between two
cycle and four.<BR><BR>Power: The OS does ok, but the DZ is far more
powerful. Maybe I need more<BR>time on the OS before a fair
comparison. I have a gut feeling however, from<BR>running this and
watching other OS owners over the years, that the DZ<BR>dominates in
power.<BR><BR>Weight: OS with ES muffler is probably 3-4 ounces lighter
than a DZ with<BR>similar muffler. But I think the DZ might be
equivalent weight with a<BR>Hatori short pipe. Not sure.<BR><BR>Fuel
requirements: DZ runs best on one type and brand of fuel: Cool
power<BR>30% heli. This is expensive stuff, and is my major gripe with
the DZ. The<BR>OS ran outstanding with 15% sport fuel. For
economy, you cannot beat this.<BR><BR>Smoke trail: DZ has a thick smoke
trail with CP 30%. This OS had fair<BR>amount of smoke, but I expect it
to decrease as I lean in. None of OS' that<BR>I see at contests have a
heavy smoke trail.<BR><BR>Overall preference: This is a little tough
because the DZ performs better<BR>for pattern, but the OS is probably good
enough. Greg Frohreich flies very<BR>well with his OS, and until I can
fly better, I wonder if I need a better<BR>engine. Still, the DZ is a
pleasure to run, with exception of the expensive<BR>fuel. I choose the
DZ as my preference, but I like the OS for the positive<BR>characteristics I
mentioned.<BR><BR><BR>David<BR><BR></FONT></BLOCKQUOTE></DIV>
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