My mechanic pulled the fuel Injector n cleaned it thoroughly !! That Fixed it purring like a kitten ! Also had shifting issue ... try turning down a lil bit below 2 RPM s if it won't stall there !! Also MUST MUST warm machine up before leaving .. shifting should be smoother with those 2 tricks !! I love my Buck 400 its just the engine sucks rest is Perfect .lol lol
I've had similiar issues with a Buck 400 Cazador n we have put in new air filter plug .. gas line review .. may try n change out fuel injector next ! ?? Love the machine just a Terrible engine ! Get what ya pay for !!