Today's Message Index:
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1. 01:07 PM - Uneven Mag Drop 912 ULS (JohnF)
2. 02:26 PM - Re: Uneven Mag Drop 912 ULS (Roger Lee)
3. 03:22 PM - Re: Uneven Mag Drop 912 ULS (JohnF)
Message 1
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| Subject: | Uneven Mag Drop 912 ULS |
This looks like a case of "It was working until I fixed it"
Annual condition inspection; new plugs at 0.027-inches, carbmate showed exact balance,
Dyna Vibe gave engine smoothness like a turbine, cylinder differential
pressure almost perfect all cylinders, began using non-ethanol 91-octane gas,
no oil consumption, crossover fittings (hoses) all tight, cruise speed normal,
climb out at max throttle 5,000+ then over 5,100 after a few moments while still
over the runway.
Spark plug wires firmly attached
"Killing" A side ignition, mag drop averages 150 rpm
"Killing" B side ignition, mag drop averages 290 rpm, so it looks like a
problem with the A side ignition.
Next try will be new plugs (again) on top of cyl #1 & 2
new plugs (again) on bottom of cyl #4 & 3 to eliminate a
bad new plug.
Anything else to check?
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http://forums.matronics.com/viewtopic.php?p=423608#423608
Message 2
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| Subject: | Re: Uneven Mag Drop 912 ULS |
What rpm are you doing the mag drop at?
Plugs are worth checking / replacing and gaps. Since you pulled the plug boots
off you may have inadvertently pulled the plug wire a little too much where it
goes into the boot. It wouldn't hurt to unscrew each one and trim the wire back
1/4" and then thread the boot back on.
I even think 150 is a little high if the rpm is 3500 and under. Average is 50-100.
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Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
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Message 3
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| Subject: | Re: Uneven Mag Drop 912 ULS |
Roger,
I run up to 4,000 rpm and then 'kill' each circuit in turn.
I have never 'unscrewed' a plug boot...I assume I can hold the main wire and twist
on the 'plug' end that would connect to the top of the spark plug. I am picking
up 4 new plugs tomorrow and will gap and install...will try that plug wire
trimming and reattaching.
Thanks for the input Roger...I wish you were a bit closer, I would just fly down
to Tuscon and put the whole thing into your hands !
John
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