Crankshaft oil pump gear

zed1015 wrote:

The tooth count is 49 on the pump and 31 on the crank which gives a 1.58 to 1 ratio.
This ratio and tooth count is the same on all Z1/900 through to GPZ1100 8 valve fours and the pump capacity/flow rate is also the same throughout so there is no advantage or upgrade available by fitting later model stock factory pumps to earlier engines or vice versa except for possible less wear on later or lower mileage pumps..
The early kickstart engines have the crank gear bolted on whilst the later J/GPZ crank gear is pressed on.
The pressed on gear on the later engines can become loose on high mileage or high horsepower engines which will periodically slip and eventually stop driving the pump.
The fix for that is to have the crank gear welded on..