dholder

here is the video I did today on a Allegro for the BM. Certainly made a difference and at the levels we are talking about which is very small it certainly works. The prop originally was very good anyway before the BM was fitted. Anything under 1 IPS (inch per second) is supposed to be acceptable. With the Rotax carb balance does confuse the readings a little so it is very important to do that first. The aircraft bucks and bounces on the ground at 5000 rpm as you would expect also being tied to a vehicle adds to this. In the air it would even much better. This one at idle was astounding . The first half of the vide is no BM the second lot of runup were with the BM fitted

David

Methylated spirits according to wikipedia. Not dangerous at all if used with common sense. It is not so highly volatile.

I do this all the time. I fill a squirt bottle that squirts a stream, like a plastic Leak-Tek bottle, with denatured alcohol. With the engine running at idle, squirt each intake connection. The engine rpm will change noticeably if there is a leak. Takes only a minute to do.