Skypilot, I am using Cool Power High Performance Heli 30%...Not sure if there's castor in it...It's what I already had for my Saitos'.

Rate I am using the glass or nylon one that was supplied with the kit...There is some vibration, but no more than expected with an engine of this size...I believe it's smoother than the Saito 180 i had..The fuel tank is mounted ahead of the wing tube, with it being at least 6" behind the carb...Absolutely no fuel draw problems at all..Don't know if it's needed but I am using large fuel line.

I might add it starts extremely easy at an idle with a starter...I have not tried hand starting it yet.