Z1OwnersClub GB

What are the differences between the z750e and gpz750a heads besides the cams ?

Smoother inlet tracts, years ago we put a gpz750 head on my mates gt750, it was deffo different when revving tho that might have been the new camchain!!! I know on my RX they're really smooth. The head we used was off an R1.

The volume of the combustion chambers are different

76-80 Z650 23.7
81 Z650 23.3 to 24.1 or average of 23.7 same as early one
82 Z650 24.8



1980 Kz750E1 24.8cc
1983 KZ750H 24.8
1983 KZ750L 25.3
1983 ZX750A1 25.9 (GPZ unitrac)
1984 Zx750E1 24.6cc (Turbo head)
1982 KZ750R 24.9cc
So you can see the GPZ actually has bigger chamber, it gets its rise in CR due to the pistons which were higher dome than std 750.
The heads on the unitrac especially the last A3 and A5 had hand finished ports around near the valve seat insert and valve guide. Do not be tempted to use the turbo head it is not much different to the std 650 in its ports and valves. There may also be some difference in the exhaust installed valve height in relation to the cam as the GPZ cams have a smaller base circle than the Z750,cam. I have been told it is possible to use the exhaust cam as an inlet cam to gain more clearance when the valve seats become worn/lapped in too much. You can get good results using either head, skimming is recommended, see following link
http://members.tripod.com/gpz_rider/tec ... AQ2000.htm

Crofty wrote:The volume of the combustion chambers are different

76-80 Z650 23.7
81 Z650 23.3 to 24.1 or average of 23.7 same as early one
82 Z650 24.8



1980 Kz750E1 24.8cc
1983 KZ750H 24.8
1983 KZ750L 25.3
1983 ZX750A1 25.9 (GPZ unitrac)
1984 Zx750E1 24.6cc (Turbo head)
1982 KZ750R 24.9cc
So you can see the GPZ actually has bigger chamber, it gets its rise in CR due to the pistons which were higher dome than std 750.
The heads on the unitrac especially the last A3 and A5 had hand finished ports around near the valve seat insert and valve guide. Do not be tempted to use the turbo head it is not much different to the std 650 in its ports and valves. There may also be some difference in the exhaust installed valve height in relation to the cam as the GPZ cams have a smaller base circle than the Z750,cam. I have been told it is possible to use the exhaust cam as an inlet cam to gain more clearance when the valve seats become worn/lapped in too much. You can get good results using either head, skimming is recommended, see following link
http://members.tripod.com/gpz_rider/tec ... AQ2000.htm

Now that Guyz is what gets my willy wet !!!

thank you chaps I have a z750 e or l head to fit, just managed to get an 810 kit from Stafford (£50 )
all I need now is a bike to fit it to

They are as cheap as chips just take your time....just bought a z750e for the engine and a few other bits for £550