Sputtering issue

[nickaloadien]

Currently breaking in a 79cc 2 stroke china doll, running nice so far but it has this issue that i’ve noticed with my other builds, when cruising with throttle open, once I let off the throttle the bike sputters like crazy so i either have to keep the throttle open or pull the clutch in. Why does it do this? I feel maybe it’s part of the break in process or too lean/rich

 

[noah9988]

Does it sound like this?

 

[Axl Myk]

Nice bike.
Let it break in for a while. The piston rings need to set.