Jack Krizman, Harley Davidson Engineer and entrepreneur, was one of the first engineers to start working on enhancing the early 70’s Aermacchi Harley’s two stroke engines; Baja 100, SX125, SX 175 & SX 250, including the development of the 1975 MX-250 prototype.
In January of 1973, Modern Cycle printed an article titled Krizman/Harley-Davidson Enduro Models. In the article they exposed the Krizman prototype developments, especially the 1973 TX-125 for endurance racing. Moreover, the article mentioned that Krizman was working on his tricked bikes during 1973-1974 for the production line of 1975.
Krizman designed and modified many performance improvements for the two stroke Harley-Davidson and aftermarket racing parts, which include: drain holes into the brakes drums, shocks variation, disk & drum brakes improvements, ignition, clutch, crank, cylinder/heads, reed valve head, frames, etc. In addition, Krizman developed his own signature pipe designs and silencer/spark arrester.
Did Jack Krizman was part of the 1975 MX-250 prototype? I do not know. But he was a major contributor of the two-stroke racing engines private modifications of the AMF Harley-Davidson motorcycle in the 1970’s.
How much Jack was involved, I do not know, but it seems with his “Goodies Price List” of Tricked parts for the two-stroke Harley-Davidson engines, that Jack Krizman, was very much involved and interested in all of the aspects of the development of a Harley-Davidson two stroke engine racing program.