1977 Xr 75

I've heard that popping is a sign of to lean a fuel mixture.Check your plug color at idle then half throttle and finally full throttle maybe up an incline and kill it without letting off on the throttle to get an accurate plug reading.Of course you need to eliminate the basics like some sort of air leak at the intake boot,clogged carb vent hoses.Does it pop on deceleration?Another lean condition.I use Honda 20 50 and change it every third ride or 6 to 8 hours.Let us know if yu solve the popping.Not sure about the points,but there cheap,justa a pain to set.