Today's Message Index:
----------------------
1. 11:21 AM - Jetting puzzler (Richard Pike)
2. 02:18 PM - Re: Jetting puzzler ()
3. 03:42 PM - Re: Jetting puzzler (John Hauck)
Message 1
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Finally got the 3.47:1 E gearbox, the 72" three blade Warp Drive prop and the 582
to be happy with each other. And working around our trashy thrashy spring winds,
it only took six weeks...
The problem was that every time I throttled back to cruise, the 582 "fell off the
pipe." Ran great on takeoff and climbout, made no difference if I pitched
the prop for a 6,000 rpm climb, a 6,250 rpm climb, or a 6,450 rpm climb, when
I pulled the throttle back to anything less than 5,000, the engine would sag off
to around 4,600 and misfire, and the egt's would go from around 1100 - 1150
to around 1000. A bit low, but not horrible.
Jetting was exactly as specified, new plugs, new plug caps, cleaned and reoiled
the air filter, new choke valves, as close to the book as I could get it, no
joy.
Yesterday I pulled the #55 idler jets and replaced them with a set of #50's I had.
Bingo! Not great, but way better. Then I dropped the jet needles one notch
and I've got my airplane back. Ran perfect.
This morning I added some pitch to the prop and tried it again, still perfect.
So here's the question: why would going from a 2.58:1 B box and a two blade 68"
Ivo to a 3.47:1 E box and a three blade 72" Warp require leaner jetting? There
is probably a good reason, and one of you probably knows what it is.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=501440#501440
Message 2
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Subject: | Re: Jetting puzzler |
Richard..
Granted this is a educated guess.. and even the "educated" part could be
in question. But knowing how 2 strokes run.. and how you have made your
changes in gear box and prop? As a computer tech, we used to align floppy
drives, and a part of that was observing the "instantaneous" speed of the
disk. How does that relate? You have a difference in the gear box type,
the gear ratio, the prop inertia )due to diameter change), and likely it's
actual mass too. And being a 2 stroke, most of the function of the engine
depends on the flow thru the engine, and even the "super-charging effects"
of a tuned pipe. If you had measured the exact speed of each part of the
rotation, and how that affects fuel flow, loading, flame progression, and
general timing.. all of the new toys may have simply changed how the engine
responds.. and while I don't know the exact amount of difference in fuel
flow from a idle jet change, or one click of the needle going leaner.. but
clearly those carbs are designed as super versatile, in their range of
available adjustments. I wouldn't question the slight changes making what
appears as big differences. Just pat yourself on the back for tweaking it
correctly! Sounds like you have it dialed in, perfectly!! And there are
other folks (reminded of the HKS and all those mods) that never got that
plane to fly right!
As other have said here, worth everything you didn't pay for the possible
reasons above. Best Wishes! Enjoy! Jerry
On Mon, 19 Apr 2021 11:21:23 -0700, "Richard Pike"
<thegreybaron@charter.net> wrote:
<thegreybaron@charter.net>
>
> Finally got the 3.47:1 E gearbox, the 72" three blade Warp Drive prop
and
> the 582 to be happy with each other. And working around our trashy
thrashy
> spring winds, it only took six weeks...
>
> The problem was that every time I throttled back to cruise, the 582
"fell
> off the pipe." Ran great on takeoff and climbout, made no difference if
I
> pitched the prop for a 6,000 rpm climb, a 6,250 rpm climb, or a 6,450
rpm
> climb, when I pulled the throttle back to anything less than 5,000, the
> engine would sag off to around 4,600 and misfire, and the egt's would go
> from around 1100 - 1150 to around 1000. A bit low, but not horrible.
>
> Jetting was exactly as specified, new plugs, new plug caps, cleaned and
> reoiled the air filter, new choke valves, as close to the book as I
could
> get it, no joy.
>
> Yesterday I pulled the #55 idler jets and replaced them with a set of
> #50's I had. Bingo! Not great, but way better. Then I dropped the jet
> needles one notch and I've got my airplane back. Ran perfect.
>
> This morning I added some pitch to the prop and tried it again, still
> perfect.
>
> So here's the question: why would going from a 2.58:1 B box and a two
> blade 68" Ivo to a 3.47:1 E box and a three blade 72" Warp require
leaner
> jetting? There is probably a good reason, and one of you probably knows
> what it is.
>
> --------
> Richard Pike
> Kolb MKIII N420P (420ldPoops)
> Kingsport, TN 3TN0
>
> Forgiving is tough, being forgiven is wonderful, and God's grace really
is
> amazing.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=501440#501440
>
>
>
>
>
>
Message 3
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New system is not loaded as much as your old system at mid and low range. Two
strokes are very sensitive to loading and unloading, mixture, and EGT. I did
lot of experimenting way back in my two stroke days. Never had a problem I couldn't
solve. Then my first flight to Alaska with the new 80 hp 912 and I developed
mixture problem I couldn't solve until well after I got back home in Alabama.
And I discovered the solution to that one by accident and experimenting
with the enricher in midrange. That was 1994.
You are working with a system that is far from standard, especially on a Kolb.
John Hauck
On the Great Loop in Astor, Florida
-----Original Message-----
From: owner-kolb-list-server@matronics.com [mailto:owner-kolb-list-server@matronics.com] On Behalf Of Richard Pike
Sent: Monday, April 19, 2021 2:21 PM
Subject: Kolb-List: Jetting puzzler
--> <thegreybaron@charter.net>
Finally got the 3.47:1 E gearbox, the 72" three blade Warp Drive prop and the 582
to be happy with each other. And working around our trashy thrashy spring winds,
it only took six weeks...
The problem was that every time I throttled back to cruise, the 582 "fell off the
pipe." Ran great on takeoff and climbout, made no difference if I pitched
the prop for a 6,000 rpm climb, a 6,250 rpm climb, or a 6,450 rpm climb, when
I pulled the throttle back to anything less than 5,000, the engine would sag off
to around 4,600 and misfire, and the egt's would go from around 1100 - 1150
to around 1000. A bit low, but not horrible.
Jetting was exactly as specified, new plugs, new plug caps, cleaned and reoiled
the air filter, new choke valves, as close to the book as I could get it, no
joy.
Yesterday I pulled the #55 idler jets and replaced them with a set of #50's I had.
Bingo! Not great, but way better. Then I dropped the jet needles one notch
and I've got my airplane back. Ran perfect.
This morning I added some pitch to the prop and tried it again, still perfect.
So here's the question: why would going from a 2.58:1 B box and a two blade 68"
Ivo to a 3.47:1 E box and a three blade 72" Warp require leaner jetting? There
is probably a good reason, and one of you probably knows what it is.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=501440#501440
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