Hi Bill,
I've been running a RM 40 in an overweight Nakke (54 oz!) for several years now, but it has taken a bit of experimentation to get where I want.
The original problems were a bit short on power.....and running forever on 4 oz of fuel! (over 10 minutes at Tucson!)
I had some custom made venturis to replace the stumpy stock one, which had 4mm bore. Jim Lee made me some with a longer throat.....about 3/4".....and upped the bore to 6mm. I've been using PowerMaster RMA 5-11-11 fuel with good results, with up to 10% for higher density altitude.
Currently, it swings an 11-5 APC at about 9000 rpm on the ground, wet 2-stroke. It pulls the beast around at 5.1-5.2 sec laps, flying on 62' lines. With the extra weight, I have to fly using momentum to keep up the speed, but it still turns corners quite satisfactorily.....even the last corner of the hourglass!
I can send you a .pdf of the drawing for the venturi for the stock nva, as well as one for a conventional type NVA.
Jim probably has the drawings on file, but let me know if you'd like a copy.
Dave Gardner