H1 Cylinders

H2 Cylinders

The H2B/C cylinders are not fitted with oil "jets", nor are the cases drilled.  To fit late cylinders on early cases you can tap the oil hole to 5 X.08, cut the end off of a #30 pilot jet, and install only the threaded portion of the jet in the hole. Don't drill all the way through when getting the hole ready to tap, so there is no way the jet can end up stuck to your piston. And use high strength loctite. The # 30 jet is about the same size hole as the pressed in jet in the early cylinders. - Bryan H.

The cylinder with the square cut out is a 1971 cylinder ONLY, it is totally unique and no other cylinder can be cut to match the porting as the liner and casting sit in a totally different position to all others. The 1972 and 1973 also had 2 more porting specs, the 1974 and 1975 are also a different spec, so there are FOUR cylinder port specs.
The pistons for the 1971 & 1972 models have a higher cut out in the skirt. - Rick Brett