The mighty Kawasaki Z900/Z1 in all its storming glory
It’s a typical early ’70s system, either not charging, or overcharging and boiling the battery. Most bikes will be fixed with a new reg/rec by now. Most people keep the old stuff when they fit a modern unit – originality is worth money.
Nippon Denso stuff was the best around back then. The needles lose their damping after time and fluctuate madly, and the red paint fades. But at £90 for a rebuild, or £75 for replicas, this is not an expensive fix.
Many believe the weavy high-speed handling is down to old cup and ball headstock tech. Not so. Dave Marsden: “The only benefit of taper rollers is so you don’t have to mess with 39 ball bearings if you do the yokes.”
Soft with antique damping assembly. Better brakes only make things worse. There’s not much you can do except fit springs properly matched to your weight and then mess about with damping oil quantity and viscosity.
Back in the ’70s nothing on two or four wheels had anything like decent brakes, so the single-piston, single disc set-up was OK. Fitting a second disc and caliper (a UK option) makes a huge difference. Z-power does a kit for £400 all-in.
Nuclear Armageddon-proof. Often they don’t even need a rebore after huge mileages. The only things that wear are the camchain tensioner blades and any other rubber components blighted by age, ie valve guide seals.
A very old, abused gearbox might jump out of second because either the dogs or the selector forks are worn. If the chain has been run too tight, the output shaft bearing can give up – a cases apart job to repair.
General wear, sloppy linkages and air leaks can all cause issues. Some riders complain of a flat-spot off tickover. Raise the tickover up from 1200 to 1700rpm to mask the issue. Better still, fit new Keihin CR carbs.
It flexes and that’s where the ‘interesting’ handling is born. Strengthening gussets and seams are the answer to maintain the allimportant original look. Better shocks help, with pattern OES at £90 a pair.
Replica 4-4 and 4-2 systems are available. Readypainted body sets are available for a modest £1300. Seats, again from Japan, are off the shelf items. Huge popularity of the model helps keeps
Check out the twin disc conversion option