Re: 86 115hp excess carbon on #1
The normal condition for a BUHW in a good running engine is light tan. It it's dry carbon then that could be the beginings of a slightly lean condition.
In trouble shooting these types of problems its always best to do the forensic's first. Run a compression test on all cylinders both cold and warm. You're looking for a significant difference in excess of 15% from original or 15% difference between any two cylinders.
Since it is only one cylinder, it's probably either a compression, cooling or spark issue. Reeds would effect 1 and 2 as well as a carb issue so I'm pretty sure you can rule them out. The motor has the switchbox/trigger/coil style ignition so you're lucky in that those parts are readily available if you need them.
I'm suspecting a cooling issue based on the plug condition. It's normal to have a carbon buildup on the piston top. Have a look and see if it's shiny and clean. That would indicate water intrusion, if theres an hourglass shape of cleaner area on the piston top that's usually a slightly lean condition and that could be from elevated temps in that cylinder.
