Rich Posted November 17, 2015 Report Posted November 17, 2015 Attached is a pic of the plugs removed after 80 hrs. using mogas 93 octane w/E-10. Only mixed avgas when traveling with Decalin. At least two of the plugs look like their running on the lean side. Over all, they're very clean with some of them having that sought after light brown tint. Comments?
FlyingMonkey Posted November 17, 2015 Report Posted November 17, 2015 Those look pretty good to me. The second from the right at the bottom looks leanest, but hard to tell without better light. I would not lose sleep over those plugs.
Rich Posted November 17, 2015 Author Report Posted November 17, 2015 030-035 when removed. Installed at 025 Plugs were removed after a 2:10 x/c with approx. 2 minutes to shut down.
Anticept Posted November 18, 2015 Report Posted November 18, 2015 Close the gap on those plugs. The wider the gap, the hotter the spark. In turn, it increases plug wear and shifts the timing slightly (this is more of a problem for magneto driven systems). Also, when taking photos, use the camera flash or put it under a "natural white" (5000k) or "daylight" (6500k) lamp. It will make it easier to see colors.
Rich Posted November 18, 2015 Author Report Posted November 18, 2015 The plugs have 80 hrs. on them and were changed last week. Previous change was 10/15/2014, a little over a year ago. Next time, after 50 hrs. I'll remove, clean, re-gap, and re-install until 100hrs.
FlyingMonkey Posted November 18, 2015 Report Posted November 18, 2015 I think I gapped mine to .028 per instructions from Lockwood...is that too wide?
Anticept Posted November 18, 2015 Report Posted November 18, 2015 Rich: maybe your gap gauge is bad. Don't use the round disc ones, those are terrible, truely terrible. Innaccurate and can crack the center electrode. You should be using feeler gauges, and a tool that lets you hook onto the ground electrode and bend it. MrMorden: this is why you should always consult the mx manual no matter how trivial the task. Spark plug gap specs changed and were made smaller.
FlyingMonkey Posted November 18, 2015 Report Posted November 18, 2015 Is .028 enough of an issue to pull them and re-gap, or just fix them next time?
Ed Cesnalis Posted November 18, 2015 Report Posted November 18, 2015 Is .028 enough of an issue to pull them and re-gap, or just fix them next time? Do they have crush washers? Can you re-use?
Anticept Posted November 18, 2015 Report Posted November 18, 2015 MrMorden: that's up to you. The book prescribes a wear limit of .35
Rich Posted November 18, 2015 Author Report Posted November 18, 2015 Rich: maybe your gap gauge is bad. Don't use the round disc ones, those are terrible, truely terrible. Innaccurate and can crack the center electrode. You should be using feeler gauges, and a tool that lets you hook onto the ground electrode and bend it. MrMorden: this is why you should always consult the mx manual no matter how trivial the task. Spark plug gap specs changed and were made smaller. Anti, I used the feeler gauge, not the disc. Correction: I rechecked the time in the logbook and it was 88 hrs., not the 80 as originally posted. I usually don't make mistakes when gapping plugs but anything is possible. I won't rule it out here. The gap is a little wide, as Roger mentioned. Going from 025 to 030/035 in 88 hrs. is quite a jump.
FlyingMonkey Posted November 19, 2015 Report Posted November 19, 2015 .028 is too wide for this time of year. The limits are .023 to .027. The hot weather climate is for a wide gap. the colder i8t is the narrower the gap. In the mild winter climate areas .025 is just fine. If you live in cold country then .023 and an engine heater would be your best investment. Rotax will even recommend .020 if you live and fly in those areas that are below zero on a regular basis. We usually recommend plugs at 75 hrs. regardless of fuel trype. I know what the book says, but it is rarely followed. For plugs costing $2 each why would someone penny pinch. Andy, I would close them down to .025. .028 will only get wider. Roger, Roger!
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