well ive made myself a mutant motor. took the crankshaft from my mephisto gt5, the piston and sleeve from a keep off 7 that i opened the exhaust port so it closes in the center at the same degree the two outside ports close as well as some cleaning and reshaping of the four small booster ports, just cleaned any flashing from all the other ports. shimmed with three .030 and one 0.010 shim, ct6 plug(could drop the 0.010 and run a 6 or 7 depending on weather) 41001 9901 pipeset.
just testing around the house so far. going to try the 2135 and some other pipes when i can get some track time in.
I also opened up the exhaust port on my silver head karma that i haven't run in just about two years, i added a few degrees to both the opening and closing of the crank a few years ago and it made a difference but not a huge one.it was always a little soft everywhere but now shes snappy like a btt with a bunch more top end than it had. I opened up the port quite a bit and am actually surprised it didn't lose anything but im sure it had RTR engine like timing numbers to begin with.