Hello, not been on here for a while I got a new carb for my GY6 125cc and I am puzzled what the extra hole is for (see photo). Have searched Google but not found a thing. It looks like it's part of the air/fuel screw channel as you can see the channel in the hole. at the moment I have put a shortened M8 bolt in it but I have found that the engine backfires when decelerating. any help from you people who know would be very much appreciated
Carburetors require an air shut off under engine braking to prevent backfiring hence two strokes only receive lubrication while accelerating in 4 strokes this is not the case I would clean the carb & check for vacuum leaks.
