The Kawasaki 650 parallel twin engine is probably one of the most underrated engines of the decade. There is absolutely nothing special about it. It’s got a very conventional 180 degree firing order, 2 pistons and 8 valves. The engine has a low 10,000 rpm limit and the power is great but far from peaky. It’ll never tear your pants off when you twist the throttle.
Then why is it the most underrated engine?
You see, the Kawasaki 650 parallel twin sits in the sweet spot when it comes to motorcycle engines. It’s a parallel twin so the maintenance is minimal. The power output is a high but not scary 68 bhp (different for each of the 4 bikes). The torque is a constant surge from a low 2500 rpm and the engine is tuned to have a strong mid range. That’s it! No peaky top end as the red line is 10,000 rpm only and no sluggish power delivery at low city speeds. It might be the perfect all-rounder!
The parallel twin setup and fairly low compression ratio keeps this engine cool in almost all conditions and the liquid cooling works wonders.
One engine in 4 motorcycles?
The 650 twin is present in Kawasaki’s Ninja 650(sports tourer), Z650(naked street), Vulcan S(cruiser) and the acclaimed Verseys 650(adventure tourer). The reason this engine performs excellent in all these platforms is because none of them require very high power or a crazy top end. The parallel twin chugs along at any speed just fine and responds well even with a couple hundred kilograms of payload.
On all these motorcycles, it can sustain 140 kmph (87mph) all day long without breaking a sweat. Two of the motorcycles (Ninja 650 and Z650) can reach a high 212 kmph (132mph) top speed. The service intervals are long 10,000km (6000 mile) hauls because the parallel twin has the reputation of being a bulletproof engine.
Kawasaki used the 650 parallel twin to its full potential by tuning it differently for each of these motorcycles. The Vulcan gets a lower power and torque output but these come relatively early in the rev range. The ninja and Z650 have fairly similar characteristics with a strong mid and upper mid range. The Verseys 650 gets a boost of power and a strong mid range to suit its extra weight.
The power outputs of these motorcycles are as follows:
Ninja 650 : 67.2bhp(8000 rpm) and 65.7Nm(6500 rpm)
Z650 : 67.2 bhp(8000 rpm) and 65.7Nm(6500 rpm)
Vulcan S : 61 bhp(7500 rpm) and 63Nm(6600rpm)
Verseys 650 : 69 bhp(8500 rpm) and 64Nm(7000rpm)
Kawasaki played it smart by utilizing the wide power and torque bands of one engine to work in 4 completely different applications. Modern engineering allows for just an ECU tune to drastically change the characteristic of an engine.
This helps the company keep R&D costs down while still putting out great products in the market at lower prices than all of its Japanese and European competitors.