Good point Gary, I hadn't considered that a little castor in the fuel may help seal up any potential air leaks around the throttle barrel. Running 2.5% castor for a while now I have not seen any negative side effects ie no gumming of valves or fuel tanks or locked up throttle barrels after prolonged storage. The positive attributes of the use of castor at the correct proportions in 4 strokes would be hard to argue imo.
Last edited by Glowgeek; 06-13-2019 at 05:21 AM.