"Here's the theory behind
"Here's the theory behind carb syncing:
To get a 2 stroke motor to idle low enough to shift it (without...you know) the spark has to be retarded something awful! (A typical car engine has at least 8 degrees advance at idle--and that's without the vacuum advance adding 10 more.) A stroke may be 10 degrees RETARDED at idle, with the carbs closed, just to get that sucker to slow down!
So...when you throttle up, you have to take all of that retard out of there, and add some advance as well BEFORE opening the carbs. If not, the motor will blubber like crazy; it may may even stall.
So...the trick is to get LOTS of advance going on BEFORE the carbs start to open. I typically get virtually all of it (the advance) in before the carbs start to open--the more the better.
Some might claim that this could cause cause pinging, from having it advanced so far, but since the carbs are barely open that is hooey!
Jeff
PS: I ran my old KG-7 at full advance ALL the time, opening the carbs only with my hand throttle. That motor had no neutral, so it wasn't a problem shifting."