Originally Posted by crassius
#73 - .024" - .61mm
never even tried one that small, are you sure that isn't too lean to get up hills?
I run that size for last 4 years in one of my bikes with a very free flowing exhaust and a 32T sprocket on a 24" wheel now, I ride 30+ mile round trips with a 4 moderate hills along the way, spark plug runs nice medium chocolate brown and the engine only 4 strokes at very low speed with only small amount of throttle being used.
I worked this jet size up by trial of plug checking and it works great on 3 of my engines, never any lean issues at all with this jet size on my bikes.