Crank Geometries

Connecting rod length — Figure 1: Image showing connecting rod length

Crank stroke — Figure 2: Image showing stroke (Stroke is also the difference of piston height at TDC minus BDC)

Below is a collective table of many of the common crank geometries, their rod length (either 89mm long rod or 85mm short rod), their strokes (38mm, 40mm), and wristpin diameter (10mm, 12mm).

Crank Rod Stamp	Rod Length	Stroke (+-0.5mm)	Wristpin Diameter
ZL40MM	89mm Long	40mm or 38mm	10mm
AF80	89mm Long	40mm or 38mm	10mm
Zeda-80	89mm Long	40mm or 38mm	10mm
No Mark	85mm Short	40mm or 38mm	10mm
Z-L	85mm Short	40mm	10mm
ZAE-50	85mm Short	38mm	10mm
ZMN80	89mm Long	40mm or 38mm	10mm
ZMN100	89mm Long	40mm	12mm
"."	89mm Long	42mm	12mm

This list may not be 100% up to date or accurate. China often changes and mixes up crank parts, causing random variations in these. Please measure yourself to be sure.