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Posted by: jeffdon Aug 9 2010, 03:58 PM

Getting some snuffling through the carbs, still feels sluggish. I think i am pretty close on mixture. Got a feeling there is some movement back and forth on my bellcrank which may be making the two halves of the engine "fight" each other. How she look?






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Posted by: tornik550 Aug 9 2010, 04:20 PM

Looks lean to me.

Posted by: tornik550 Aug 9 2010, 04:24 PM

Heres a thread that I started recently. Some of the responses were very helpful to me. (I am obviously no expert so my "it looks lean to me" comment should be taken with a grain of salt).

http://www.914world.com/bbs2/index.php?act=ST&f=2&t=109442

Posted by: jeffdon Aug 9 2010, 04:30 PM

Thanks man. Some good info in there.

Posted by: '73-914kid Aug 9 2010, 05:47 PM

If the engine seems to chirp or cough, chances are that it's lean.. hence a "lean pop-back". As far as the ceramic insulator, it looks lean to me. lean enough to burn off any residual carbon left by un-leaded fuel as well..

What's your ignition system and plug gap?

Posted by: jeffdon Aug 9 2010, 08:19 PM

Pertronix on the igy. Gap is 28 thou. I think

Posted by: rickthejetman Aug 9 2010, 08:25 PM

white ash indicates lean but its not heavy so i'd say slightly lean. how long has this plug been in use? since your aircooled you want slightly rich. i'm an airplane mechanic an i can tell when an owner has been trying to get "better fuel economy" lol. aircraft owners are the cheapest people on the planet.

Posted by: Project 6 Aug 9 2010, 08:28 PM

slightly lean is like being slightly pregnant....

Posted by: rickthejetman Aug 9 2010, 08:57 PM

hahaha very true. detonation kills engines.

Posted by: SLITS Aug 9 2010, 08:58 PM

To get an accurate plug reading, you have to do a few hot laps (preferably on a track)or a run down the freeway. When you decide you've had enough, 3 laps, you kill the engine entering the pits. Before the engine cools down, you pull the plugs, carefully.

That said, a light brown to medium coloration to the center electrode is desirable.

White deposits are the burned additives in street gas.

A bright white center electode is lean; Black is rich.

That's what I know ....

Posted by: charliew Aug 9 2010, 10:18 PM

The only way I ever got a reliable plug reading was to kill the motor at wot and immediately push the clutch in and coast to a stop and pull the plugs, all of them. It didn't need to still be hot just no running after wot to get a real under load reading. It looks like it was just put in and run about two miles to me and deffinately not as rich as a aircooled motor should be. It looks like it got pretty hot. You also didn't say what fuel it is burning.

Posted by: ME733 Aug 10 2010, 07:44 AM

.................Looks slightly lean...plug gap appears ok....And it appears that the greyish coloration on the spark plug threads is ..anti-sieze...and the plug has not run very long. Anti-sieze SHOULD be used on the spark plug threads., Especially if you know that you will be removing and installing plugs from a HOT engine. Removing plugs from a HOT engine is when the heads aluminum spark plug threads are prone to damage...cracking, breaking off, stripping etc...I hope you used, or will use, anti-sieze, as well as everyone else.