After a pretty good search for OE and aftermarket pistons I have contacted several manufacturers about making a run of custom pistons for the 1300. There are some available in Germany, and there are the cheap "big bore" kits on e-bay that are cast pistons.
JE and Weisco can make custom pistons for the 1300 from 62 to 64mm size, they are quite expensive though.
Ross Racing can make them too, size options from 62 to 64mm with rings and pins. They have a minimum order of just 2 pistons, but offer a discount for 3 or more sets for the 1300. Price would be under $800 for a quality forged piston set. Not sure what size I would want to go, maybe 63mm (second factory oversize) but that is up for debate if other people are interested.
Send me a message if you may be interested in a set of pistons for the 1300. I would like to have them made by this fall.
1981 KZ1300
