And as promised. Specs for the stock KZ650 pistons.
KZ650 76-82
Bore x Stroke: 62 X 54 mm
13001-1002 PISTON,STD
PISTON DIA.: 62.0mm tapers >61.5mm at rings (Note the taper just above the pin in the first pic above.)
PISTON PIN C to DOME: 31.50mm
PISTON PIN C to DECK: 24.50mm
OVERALL HEIGHT: 58.25
DECK to SKIRT BOTTOM: 51.25mm
DOME HEIGHT: 7mm
PIN LENGTH: 52.25mm
Note: 58mm dia. dome offset to intake. 4.0mm flat shoulder at exhaust.
Note: No longer available stock, but 0.50mm & 1.00mm overbore available through IMD Piston Co. in the UK.
http://stores.ebay.com/IMD-Pistons/_i.html?_nkw=kz650&submit=Search&_sid=1028788763Note: 64mm big bore available through Wiseco.
From '80 KZ650F1 service manual:
Cylinder bores:
Std dia: 61.995-62.003mm
Wear limit: 62.100mm
Piston/bore clearance: 0.032-0.055mm (0.0013-0.0022in)
Connnecting rod:
Big end journal OD:
Unmarked: 34.984-34.994mm (1.3773-1.3777in)
Marked '1': 34.995-35.000mm (1.3778-1.3780in)
Wear Limit: 34.97mm (1.3768in)
BE ID:
Unmarked: 38.000-38.008mm (1.4961-1.4964in)
Marked '1': 38.009-38.016mm (1.4964-1.4967in)
Wear Limit: 35.94mm (1.4150in)
Journal clearance: 0.034-0.076mm (0.0013-0.0030in)
Wear Limit: 0.11mm (0.0043in)
Small End:
Gudgeon pin OD: 14.994-14.998mm (wear limit: 14.96mm)
Piston boss Dia: 15.004-15.009mm (wear limit: 15.07mm)
Small end bush dia: 15.003-15.014mm (wear limit 15.05mm)
Piston boss to gudgeon pin clearance: 0.006-0.015mm (0.0002-0.0006in)
Gudgeon pin to small end bush clearance: 0.005-0.020mm (0.0002-0.0008in)