ORIGINAL: huddlehd2

The previous advice is good. I run a ThunderTiger 46 Pro on my LT40 with excellent results with an 11X6 prop. The 10X6 permitted the engine to turn more rpm but with the 46 the 11 inch prop is best. I would change out the wood prop for a plastic Master Prop for better balance etc. I see the LT40 running both the LA40 and several makes of 46 engines with excellent results. You might consider the 10 inch prop as the best for the LA40.

Hud