RE: MOKI RADIAL Care and Maintenence
Kochj,
I notice nobody has commented on your question about engine selection. Here's one opinion:
You're right about the 46% Yak 54. However, I don't think you're going to be happy with the 215 in the 40% either. The 250/215 have comperable performance to a 150 twin or even a 120 twin depending on the particular engine. The advantage of the radial is much higher torque at lower rpm. Consequently, the radials generally use much higher pitch props. For a 250 the optimum two blade prop seems to be a 32 X18.
If you are going to fly IMAC or 3D, you should probably consider 180 to 220 twins, which will produce much more raw power. Also, any reduction in airflow across the engine will be poorly tolerated by the radial. If I were considering something as large as 46%, I would give serious consideration to a 400 radial or 220+ twin.
I bought a 250 from a guy who flew it in a 33% Yak in IMAC and was very disappointed. I found out the hard way that he had also cooked the engine. The first year the internal ignition gave out ($450) and that three of the cylinders had below spec. (125 psi min.) compression. Needless to say I was thrilled.
If you are flying at sea level, performance is obviously best.
Sorry to dampen your dream, but I would get some other opinions before I would invest too heavily in your project.