Re: sparkplug gap size
For the record, I had mine (B6HS in a 50cc HT) gapped at .032 and it ran pretty well. Then I added an SBP pipe kit, a hi-flow air cleaner, and it ran ... differently. Hard to start, low power. It was now a "Morose Time" engine.
I decided to put the gap back to .026, and it perked right up. Night and day, I tell you. I didn't expect it, either, but there it is.
The thing to know about spark plug gapping is that a narrower gap makes it easier for the plug to spark (less resistance), but generates a smaller spark. A wider gap is harder to spark, but generates a bigger spark. What you want is a balance of the two; a gap wide enough that you get the fattest spark that the CDI is able to consistently generate. There's also a theory that a smaller gap allows the plug to spark just a bit earlier, and a larger gap allows it to spark just a bit later, which would have a teeny tiny effect on ignition timing, but I don't know that anyone has looked into that at all.