Don't know if this is anything but anyway.
I saw this 175cc sachs piston on ebay in germany.
Ships worldwide it says...
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&category=65304&item=7926848911&rd=1
Rought translation on this listing:
The piston is an original forged piston made by / Elko 1493; 138er alloy; type 63P4. The set consists of piston + rings, measures 63.50mm! It is for KTM Moto Cross and terrain sport machines with 175 ccm. From 1976th until??
No exchange or guarantee etc.
Evtl. also of interest for driver of machines of: Maico, Hercules, special it, KTM, Husqvarna, Puch, stuff, Kreidler, Zündapp, concrete, SWM, Laverda, Bultaco, Montesa, Ossa, Honda, Yamaha, Suzuki, Kawasaki and others.
Donny