Kolb-List Digest Archive

Mon 04/19/21


Total Messages Posted: 3



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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    Time: 11:21:33 AM PST US
    Subject: Jetting puzzler
    From: "Richard Pike" <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 2


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    Time: 02:18:10 PM PST US
    From: <1957grnchev@bluemarble.net>
    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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    Time: 03:42:46 PM PST US
    From: John Hauck <jhauck36@outlook.com>
    Subject: Jetting puzzler
    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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