merc guys

Need help with this problem.
Changed spark plug, gap was preset at 35 and merc requires 40 gap would this make a difference on reading the spark plug color?

Ran motor set at 22 degree 62 jets w/ 3 gallons gas spark plug almost all white with 1 side light tan, would this mean too lean or did not run enough gas to get color on plug? rpm 7000 mph 58.3

Changed jets to 64 made a couple of passes motor ran good until 6500 rpms then stalled a little then came up to 7000 rpms, could this mean too rich speed was 55.5 mph . Spark plug turning a little tanner.

Are you running 10 % ethanol gas? The plugs in my inboard (granted it's a 4 stroke) run shockingly white all the time since I was forced to run that stuff.

Jeff

PS: My late and sorely missed buddy ran methanol in his race car (S B Chevy). Plugs were always pure white, and it was jetted perfectly.

yes with 10 o/o ethanol

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Originally Posted by Fastjeff57

Are you running 10 % ethanol gas? The plugs in my inboard (granted it's a 4 stroke) run shockingly white all the time since I was forced to run that stuff.

Jeff

PS: My late and sorely missed buddy ran methanol in his race car (S B Chevy). Plugs were always pure white, and it was jetted perfectly.

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Originally Posted by Nason

Need help with this problem.
Changed spark plug, gap was preset at 35 and merc requires 40 gap would this make a difference on reading the spark plug color?

Ran motor set at 22 degree 62 jets w/ 3 gallons gas spark plug almost all white with 1 side light tan, would this mean too lean or did not run enough gas to get color on plug? rpm 7000 mph 58.3

Changed jets to 64 made a couple of passes motor ran good until 6500 rpms then stalled a little then came up to 7000 rpms, could this mean too rich speed was 55.5 mph . Spark plug turning a little tanner.

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Tried & true way of jetting a 2 stroke. Set timing at stock timing. Set stock plugs at stock gap. Warm up engine. Take boat off trailer. Put in brand new plugs. Start engine & go to full throttle. Run about 20 to 30 seconds shut off engine while at full throttle. Check plugs. Tan is best at temperature & humidity. ( I like brown ). Make jet adjustment, put in new plugs and do again. Then play with your timing if you want. Quality of fuel will make a difference here so be carful & read piston.

Is it that necessary to use NEW plugs each time?

Mr. Cheapskate

With our racing program in NBRA where we run 30, 40 and 44 Merc's we found that with 10% ethanol you have to go richer. When we run pure fuel we are at .076" in the KC-6's carbs and with 10% were at .781" for jet sizes. Hope this helps. From the little I know about your setup I assume the plug read shows your lean. You really like to see a dark tan.

Alan

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Originally Posted by Fastjeff57

Is it that necessary to use NEW plugs each time?

Mr. Cheapskate

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Yes every run.

jet it until it fourstrokes and go back down 2-4 sizes.