So I am starting to tune my Maxi. Replaced the stock intake and bing with a 14mm intake and 14mm bing. In addition, I also tossed the stock air box and replaced it with a hi-flow filter. It bogged right off the bat so I obviously had to get a larger jet.
I bought a range of jets (carb had a 60 in to start) 62-80 and started trying them out. I basically started a few on the lower end and had issues with bogging. I then went far and thought, I'll just go high to where I know four-stroking will start and at least I'll know where to move down from (because the last thing I want is to get hot and seize). I went to a 72. Things were alright, didn't seem to hear any four-stroking, but it was bogging at points in acceleration. So I tried to check it out with a chop.
Rode for about a half mile to a mile and got it hot. Killed the engine and came to a stop and changed out the plug (using NKG B6HS). Rode it for about a half mile and killed it again, changed the plug out and rode home. Saw no color on the ceramic insulator and the copper metal nub in the middle was a dull dark copper.
I decided to move up three sizes to see if I got anything. Moved up to a 78. Rode well. No real bogging during acceleration, and at top speed going for about a mile or so I got only small spurts of intermittent four-stroking (less than a second if they did come). Finally I'm close! Ran a plug chop and saw pretty much the same. What is the deal?