Working on finally trying to acquire the skills to read spark plugs at the moment, never really had the patience to do this thoroughly. Currently tuning on a vintage 500cc air cooled all aluminum single cylinder motorcycle (one cylinder, should be easy right?) Bike has been parked for almost three years. Working out some issues with it from just sitting.
Running a Mikuni Carb, points ignition distributor with advance similar to our oem Mopars, timing was set (in years past) at 32° total but can’t exactly remember initial and at what rpm total came. Want to say 10° initial and 32°@2000 or so.
Anyway, I’ve got my idle mixture setting spot on, nice caramel color and now have moved on to 1/2 throttle “jet needle” and “needle jet” midrange tuning. Did a 1/2 throttle run (approx
4500 rpm) for about 5 minutes with a new NGK BR8ES plug and this is what I’m getting. Looks lean, probably need more fuel? but my question relates to timing and possible heat range of the plug:
Looking at the strap you can see the two distinct discolorations. Not sure about heat range. I’d think I need to get the jetting dialed in first for that?
But regarding the strap indicating timing, what do you think? Any input greatly appreciated
Running a Mikuni Carb, points ignition distributor with advance similar to our oem Mopars, timing was set (in years past) at 32° total but can’t exactly remember initial and at what rpm total came. Want to say 10° initial and 32°@2000 or so.
Anyway, I’ve got my idle mixture setting spot on, nice caramel color and now have moved on to 1/2 throttle “jet needle” and “needle jet” midrange tuning. Did a 1/2 throttle run (approx
4500 rpm) for about 5 minutes with a new NGK BR8ES plug and this is what I’m getting. Looks lean, probably need more fuel? but my question relates to timing and possible heat range of the plug:
Looking at the strap you can see the two distinct discolorations. Not sure about heat range. I’d think I need to get the jetting dialed in first for that?
But regarding the strap indicating timing, what do you think? Any input greatly appreciated
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