I got a shitty looking plug and last 1/4 throttle seems to be bogging out . i was told to use a 4% oil fuel mix on this puppy....compression seems ok, no problems in starting or idling, just bogs a tad at 3/4 throttle and up with a small loss of power/acceleration, i upped the main jet and it made it worse. I've only ever done 2% mix on my p series vespas. so 4% seems odd to me.
If i drop to 3% and give it a blat to check plug, will i do any damage do you reckon?