An Old Newbie to motor bicycle

[Jones1701]

80cc 2-stroke motor.
80 miles into break-in period.
16:1 mixture
AMSOIL, synthetic, Saber professional
Premium unleaded gasoline.
maintaining 15 to 18 mph.

I must maintain speed above 13 mph to Minimize sputtering.
As I decelerating, sputtering increases. Starts wanting to stall out at 10 mph.
15 mph and above, no sputtering.
is this normal?

When I am done with break-in period and move to 20:1, Will this change?
Will black or oil seepage from exhaust also stop?

thank you

 

[Greg58]

Welcome to the forum, you did what most everyone does, mixing at 16/1 per instructions. Those instructions have been around for years and we're based on 30w regular motor oil, I have found that 24/1 for a couple of tanks works well for break in, then 32/1. I have two engines that are over 10 years old running on that mixture. I use Lucas semi-synthetic, it's smokeless and works well in every two stroke I have.