By NastyNils·
Motorcycle comparison · Naked Bike
Kawasaki Z650 (ER 650 K-TC) vs Z900 (MY2020)
Kawasaki Z650 vs Z900: no fairing, no excuses. Here's how to pick.
Tip the Kawasaki Z650 into a tight bend and it's turned in almost before you've asked. The Kawasaki Z900 settles into the arc as one piece.
So which one do you buy?
The Z900 has the edge if…
Sporty riding on twisty roads
Narrow edge: Z900
In the twisties, the Z900 asks a bit less of you to go quickly. The difference is harder acceleration. Call it a modest edge.
Which one's the smarter buy
No clear winner on value
Neither bike is the clear better buy at these used prices. The Z650 costs less, but that doesn't make it the smarter spend.
What makes each one tick
Z650
On the Back of the Dragon, the Z650's trellis frame snaps from one switchback into the next. Its parallel twin answers the throttle with a steady swell of torque that's easy to meter out. There's honest shove off each exit. The low seat puts both boots flat at every stop.
Nils rode the Z650 in Austria in 2023 (NastyNils Testride).
Z900
Hard on the gas out of a corner, the Z900's front wheel goes light, yet the frame doesn't weave or twitch. It hooks up and drives. A bump on a fast backroad hits suspension that's set up right, and the bike stays planted over it. The inline-four revs willingly right up to the limiter.
Nils rode the Z900 in Austria and Switzerland in 2020 (NastyNils Testride).
The Voice of Experience
What actually separates them
- The Z650 has the lower wet weight: 412 lb (187 kg) vs 467 lb (212 kg).
- The Z900 makes more peak power: 125 hp (92 kW) vs 68 hp (50 kW).
- The Z900 makes more peak torque: 73 lb-ft (99 Nm) vs 47 lb-ft (64 Nm).
Which one for the way you ride
Comfortable long-distance riding
Look elsewhere
Neither of these is a mile-muncher. If big days are the plan, keep looking.
A confidence-building first motorcycle
Sits this out: Z900
The Z900 makes too much power to start out on. Build your skills on something smaller first.
Nothing splits them on commuting and trips with luggage. Ride both back to back and the decision usually makes itself.
Who each one is built for
What's good, and what you'll live with
Z650
What owners say
Strengths
- Lightweight and nimble handling
- Approachable parallel-twin engine
- Low, comfortable seat height
- Modern TFT display with smartphone integration
Z900
Strengths
- Approachable Or Fast, Your Call
- Proven Over Months Of Testing
- Brakes Beat Their Spec Sheet
- Seat Fits A Wide Range
- Planted, Precise Chassis
Trade-offs
- Handlebar Too Thin
- Menus Fight Back
- Firm In Daily Traffic
- Snatchy Throttle Down Low
- No wind protection
Known problems to check before you buy
Z650
No confirmed faults on file yet. That's not the same as fault-free.
Z900
- Base Model Suspension Struggles with Spirited Riding and Heavier Riders The standard suspension—KYB USD fork with no compression damping adjustment—dives excessively under hard braking. The rear shock sags during acceleration. It proves inadequate for heavier riders (200+ lb) and two-up riding. The setup is designed primarily for commuting and medium-speed riding. The 2022 SE with Öhlins S46 dampers and improved fork solves these issues.
- False Neutrals and Clunky Transmission The transmission occasionally misses shifts, especially during quick upshifts above ~6,000 rpm. Most frequent between 2nd-3rd and 3rd-4th gears. Design-related play in the shift linkage. Downshifts described as clunky. Issue carried over from previous model—engine and transmission are carry-over parts.
- Front ABS intervenes prematurely under hard braking The ABS calibration is conservative and tends to intervene early, particularly at the front wheel under hard braking or over bumpy and uneven surfaces. Riders feel pulsing at the brake lever and a lengthened stop before the tire has reached its real grip limit. The system has a single fixed calibration that does not change with the selected riding mode, and there is no rider-selectable ABS-off function, so the early intervention is present at all times.
- Snatchy/Jerky Throttle Response at Low RPM The Z900 exhibits jerky, on/off-like throttle response at low RPM and speeds, particularly in 1st and 2nd gear. The motorcycle lurches when holding a constant low speed. Improved compared to the 2017-2019 generation, but not resolved. The first degree of throttle turn has a sharp snatch that disrupts smooth application, and snatchy low-speed throttle manners persist. Caused by emissions-related ECU tuning, not a mechanical defect.
- Unstable Bluetooth Connection, App Crashes, Pairing Issues The Kawasaki Rideology app (for the TFT display) exhibits recurring Bluetooth connectivity issues on both iOS and Android. Pairing drops after restarting the motorcycle, particularly with Android/Samsung devices. In rare cases, the cockpit's Bluetooth chip fails entirely, requiring instrument cluster replacement. App update 2.8.2 added a requirement for internet connectivity during the Bluetooth handshake.
- Turn Signal Mount Rubber Inserts Become Brittle and Break The rubber inserts holding the stock turn signals in the body become brittle and break, causing the signals to hang loose on their wires. Vibration and UV radiation accelerate deterioration. OEM replacement turn signals also fail within 1–2 years. Affects multiple Kawasaki models of the same design, not just the Z900.
- Idle RPM Decreases Over Time, Causing Rough Running Idle RPM gradually decreases over time, resulting in rough idle, stumbling, and occasional stalling. Some owners report idle RPM dropping below 1,000. Cold-start idle can climb to 2,500 rpm. Possible solutions include idle RPM adjustment, ECU software update, and fuel quality verification.
- OEM Front Brake Pads Wearing Out Faster Than Expected The stock sintered brake pads wear out during normal use after approximately 8,000–10,000 miles until reaching the wear limit. Inner pads wear faster than outer pads.
- Surface Corrosion on Stock Steel Screws and Fasteners Stock steel screws and fasteners develop surface rust, especially in humid or coastal climates. Kawasaki uses standard steel fasteners instead of stainless steel or coated hardware.
What they cost used
These prices compare a 3-year-old Z650 with a 3-year-old Z900.
- Z650
- about $6,000
- Z900
- about $8,000
At three years old, the Kawasaki Z650 sits around $6,000 while the Kawasaki Z900 runs about $8,000. That's a $2,000 gap in the Z650's favor. These are US market estimates, not live listings.
What they share
- Cooling
- Liquid-cooled
- Gearbox
- 6-speed
- Final drive
- Chain
- Front brake
- 300 mm
- Front tire
- 120/70-17
Where the spec sheets split
| Z650 | Z900 | |
|---|---|---|
| Seat height | 31.1 in (790 mm) | 31.5 in (800 mm) |
| Wet weight | 412 lb (187 kg) | 467 lb (212 kg) |
| Z650 | Z900 | |
|---|---|---|
| Displacement | 649 cc | 948 cc |
| Engine | Parallel twin | Inline-four |
| Power | 68 hp (50 kW) | 125 hp (92 kW) |
| Torque | 47 lb-ft (64 Nm) | 73 lb-ft (99 Nm) |
| Z650 | Z900 | |
|---|---|---|
| Fuel economy | 53 mpg (US) / 4.4 L/100 km | 44 mpg (US) / 5.3 L/100 km |
| Fuel capacity | 4.0 US gal (15 L) | 4.5 US gal (17 L) |
| Z650 | Z900 | |
|---|---|---|
| Fork | Telescopic | Upside-down (USD) |
| Rear tire | 160/60-17 | 180/55-17 |
| Wheelbase | 55.5 in (1410 mm) | 57.3 in (1455 mm) |
What comes fitted, what costs extra
| Z650 | Z900 | |
|---|---|---|
| ABS | Option | Standard |
| Ride Modes | Not offered | Standard |
| Manually Adjustable Front Suspension | Not offered | Standard |
Head to head, area by area
Both bikes on the same scale, one area at a time.
