Re: reading plugs and tuuning motor
As Don says, the only way to tune by reading plugs is to do a sustained power run to bring the plugs up to typical operating conditions, then chop the ignition. On a car or motorcycle you do this by turning off the ignition as you push in the clutch or knock it into nuetral. ANY idling will distort the results on a carbureted engine (fuel injection is different, the high pressure and small orfices of a fuel injector vaporize the fuel as well at idle as at speed). NOTHING wrong with black plugs at idle conditions on a carbed engine. Air mass flow is too low, fuel isn't atomizing very well at idle conditions in a carbed engine. You can diddle the idle ajustment screws all you want to, but as long as the engine will idle the plugs are going to be dark at idle. No way to vaporize sufficient fuel at low air flows without having excess fuel to begin with.
If you want to read your boat plugs, run it where you're interested (cruise, full speed, etc) for several minutes then turn off the ignition just before you pull the throttle back to nuetral. DON"T BE SURPRISED IF YOU SUCK SOME WATER INTO THE MOTOR AND DESTROY IT!!!! This is probably why this technique is not typically used on boats ......
Starts good, idles good, and runs good at any speed.
I just say lean it up little over all,
Are you crazy? Too much time on your hands? Just want to mess with something? Go ahead and lean it out if you like, maybe it will go .00003 MPH faster, or use 1/100 gallon less gas every year. Maybe give the distributor a good random twist and adjust the timing some at the same time. Sounds like a good trade to me to risk burning up your engine when you lean it out too far .....
