Hi,
I've followed this thread with some interest. I have a background racing karts, specifically 100cc air cooled sprint karts, and roadracing 125cc shifter karts and most recently 250cc Superkarts.
With the 125cc shifter karts, we are using MX derived engines, typically CR-125 and YZ-125 liquid cooled two strokes. The engines are square....54mm bore x 54mm stroke and use nikasil plated cylinders. The hot 125cc setup was a Honda RS-125 cast racing piston using a single Keystone style ring. This is a GP motorcycle racing piston. We spent many hours on the dyno working on the engines, optimizing them for pipes, digital programmable ignitions (with multiple advance curves) and of course the intakes....all used reed valves.
###################################################
Good post Erik,
I have been out of the timbersport racing scene for some time now. I built my 1982 Yamaha YZ 125 J liquid cooled hotsaw almost 26 years ago. It too is a 54x54 but it has a cast iron cylinder sleeve liner and 1 ring. When did they switch to nikasil and for what reasons?
Willard.