Although the heart of the Z650 - its parallel twin engine - is relatively unchanged, it does gain an assist and slipper clutch and a bit of a retune that sees its power very slightly decreased to 68hp but its mid-range boosted and Euro4 regulations satisfied. However the real key in the ER's transformation to Z comes from its new chassis. As well as a totally new (H2-mimicking green) frame, the swing-arm is also new and now has a more conventionally located damper rather than the horizontally-mounted item on the ER. Impressively, Kawasaki claims that these changes alone have trimmed nearly 13kg off the bike, which alongside other small mods such as new clocks, styling, dash and tank sees the Z650 tip the scales at a claimed 187kg, which is 17kg lighter than the ER-6n. And it shows up markedly in the ride.
Smaller, lighter and better handing
Against the new breed of middleweights, the old ER was starting to show its age. This was a bike first launched in 2006 and while it had been revised, most noticeably in 2012 when it got a new chassis, that was a long time ago and the MT-07 has moved the game on. Against the Yamaha the Kawasaki felt soft on its suspension and a bit cheap while the engine failed to match the MT's storming parallel twin. While the new Z still can't match the Yamaha's motor in terms of outright performance, the chassis revision now mean it is very much in the same ballpark.
The revisions to the chassis have taken the slop out of the ER's handling and the Z is a really surprising package in the bends. It feels incredibly narrow (a feeling accentuated by its typically ER narrow bars) and the weight loss makes it far more nimble at both fast and slow speeds. The revisions to the suspension, including the damper's new position, transform the ride quality and on a twisty road the Z is more than a match for the slightly overly soft and squishy MT. But its engine still can't quite compete.
Big bang over speed
Despite both the ER and MT using the same parallel twin format, the MT's is still the better and more engaging motor. Power-wise there is only 7hp and a few pound foot of torque in it, but the Yamaha feels newer, fresher and faster to rev compared to the Kawasaki. When you rev the Z650 it feels like an old-school engine with big pistons that are working hard as they thump up and down. It's almost V-twin like in its character where the MT is far quicker to respond. Is this a bad thing? Not at all; it's just a different type of feeling and when it comes to throttle response, the lightness of the clutch's action and torque, there is little to fault on the Zed - it's just the Yamaha tends to do things quicker. I also found the new digital rev counter a bit unpleasant, but that's a personal thing.
The middleweight class is a serious battle ground and very important to manufacturers. How important? The MT-07 is Yamaha's best selling bike in Europe, that's how important it is! While for my money the Z650 doesn't quite match the MT in terms of engine performance, it can certainly match it in every other aspect and probably out handle it to boot. And that means it is now very much in the hunt where the ER-6n was left at home by the fire nursing a cup of milky tea. The MT doesn't suit everyone and, if you like the overall Zed-family styling, the Z650 is a genuine middleweight option that won't disappoint. And at £6,099 it is exactly the same price as the Yamaha, which is certainly no coincidence...
Engine: 649cc DOHC parallel twin, water-cooled, 8v
Power (hp): 68@8,000rpm
Torque (lb ft): 48@6,500rpm
Top speed: 110mph (est.)
Weight: 187kg (wet)
MPG: 55 (est.)