After re-reading my previous post, it reminded me of a couple of other modifications I have done...

The crank can be modified by bell-mouthing the opening of the inlet passage (the outlet, where the mixture flows into the case )

Another is a "Turbo" cut-out from the above mentioned bell-mouthed inlet blending into the counter weight. If you don't know what this is, check out the link I posted to the Savage .25 engine modificatons.

Another is a radius on the leading edge of the counter weight. Be careful not to remove much material, so you don't throw off the balance. (too much )

JB weld in the induction passage just under the carb and blended to a nice radius works well on engines that don't have a ball milled passage.

I did the above mods to the aforementioned Webra .50