I have a US 41 engine installed inverted (spark plug facing down) on a 1/4 scale super Decathlon plane. My problem is that whenever I try to prime the engine, the spark plug gets wet and and no spark is produced until I remove it and clean it.

Is there an easier way to prime the engine other than putting a finger on the carb or aplying fuel on the intake? maybe something like the small plastic priming bulbs that some engines have?

Has anybody else used this engine on an inverted position?

Any comments and suggestions will be appreciated. Thanks.