How does 15,100 with an 11 X 5 mas on 10% sound? I didn't check it before the mods, because I didn't want to run it, then disturb the piston/liner wear pattern when I took it apart to modify it.

BTW that was "open faced" so I will have to try it again with the mini pipe that came with the engine the next time I run it.

I also got that same r.p.m. with a Mac's fuse. top header, un-cut...what does that mean? I don't have very much experience w/ tuned pipes. That means it's too long, right? I need to get some more experience with tuned pipes.

BTW...I don't consider it "hacking"...I consider it an attempt to optimise the stock set-up. You're basically just port matching and rolling the edges. Adding guide channels is a little more advantageous, but it's a mod that apparently works well in the car engines?

After seeing the insides of a lot of r/c car engines, and doing mods on various 1:1 car cyl. heads for many years, I know a few things about flow velocities, etc. etc. etc. but I'm always learning something, especially here talking to you guys!

Edit again: Forgot to say that the MVVS .49 I have has the older 7mm carb. and it has the natural alum. head.

All this has made me want to do some more testing on the .49...
When the weather gets to about the same temp. as it was the first time I tested it I will try some more props and the pipes.
I will have to check the "diary" for the exact conditions, but IIRC it was an early summer morning about 70 degrees.
I am at about 500' above sea level here.