merc guys

[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.

[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.

[Nason]

yes with 10 o/o ethanol




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.

[dave hensel]

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.

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.

[Fastjeff57]

Is it that necessary to use NEW plugs each time?

Mr. Cheapskate

[Aeroliner]

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

[dave hensel]

Is it that necessary to use NEW plugs each time?

Mr. Cheapskate

Yes every run.

[89HST]

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