This is a late response to a thread I've only just found. First, a thanks to Scottb613 for holding his ground like a gentleman, then to those who responded with positive solutions. They solved an issue I've been struggling with myself.
Having worked both as a manual writer and a tech support person, with RTFM on the office wall -- although of course never spoken to clients -- I have to say that in this case the manual doesn't cut it, and the superior attitude expressed by some seems inappropriate.
The only way to resolve the backfire problem is to completely fly by the book, up to and including carb temperatures. How many simmers -- part-timers all -- read with that attention to detail, fly like that, or should be expected to?There's nothing in the manual, at least that I've found, that refers to backfires in flight and how to resolve them. Not only that, but in the graphic on instruments, there's no label I can see for carb temperature, the key to the issue.
So to me it seems that Scottb613's initial query was an entirely reasonable one, and the somewhat snarky responses both inappropriate and deserving of at least a mild apology.