If your tank center isn't approx. lined up with the carb that can cause troubles in various attitudes such as stright up or down. How? If that tank center is off the your tuning will always be a compromise and either nose up or nose down will compound the tuning problem in the worst way or direction. A too low tank will necessitate an overly rich LS needle or idle setting and then pointing the nose straight down pushes it over the edge rich, wet plug, and deadstick. A hot plug can help with this compromise even the OS F.

Thanks,

Ernie Misner