I've noticed in all my OPE engines, I have varying levels of crud in the spark plug hole. I currently use ethenol free gas but had previously ran regular gas with fuel stabilizer. All my OPE engines run fine but sometimes I have to take the spark plug out to clean because of carbon buildup. Otherwise it would be extremely hard to start. I've used Techron or Gumout All-in-One every time I refill the gas tanks so I'm a little surprised at the buildup.
Any ideas?
Any ideas?