Guys,
Just to double check, I did a second test this time with the low nitro fuel (first test was 10% Byron's with oil added to get to 28%) I had used in the fuel can but from this time from the plastic jug, no brass contact. Same result, one pull through, several flips forward and back, battery on, spinner flip - running solid 4 cycle. I adjusted the needle into a rich 4 cycle, tacked at 9600 on the 9.5x6 prop with muffler. Nose up break to 2 cycle, level back to 4. BTW, the bypass mod where you fill up about half with either a stick or JB Weld works great, added several hundred rpm from prior runs at about the same setting. Easy to do.
I did a search on brass it is zinc and copper but there are many variations including addition of aluminum, lead, etc. I have no idea what blend K&S tubing is but I won't let it sit in raw fuel anymore.
Best, DennisT