Long-Term Kawasaki Ninja 1000: Sprocket Swap

Long-term update: Final-drive ratio change with Supersprox countershaft and rear sprocket

WRIST: Kevin Smith
MSRP (2014): $11,999
Miles: 7,388
MPG: 39
Mods: Final-drive ratio change with Supersprox countershaft and rear sprocket

Not everyone who rides the Ninja 1000 finds it bafflingly undergeared, but I do. And there is substantial forum chatter concerning sprocket swaps. Kawasaki supplies the bike with a 15-tooth countershaft sprocket and a 41-tooth wheel sprocket. Readily available parts allow going up one tooth in front and down as many as four in back. To test gearing, I moved through a sequence, first installing the 16-tooth countershaft sprocket, then fitting a 39-tooth rear, followed by trying a 37-tooth rear sprocket.

Stock gearing:

15/41 sprockets, 2.73:1
13.9 mph per 1,000 rpm (sixth gear)
5,400 rpm @ 75 mph (true speed)

Many of us (not drag racers or stunters) think the Ninja 1000's legs are just too short. I leave a stop in first gear, bang off five quick upshifts, and run around in sixth all day. On the freeway, the busy engine character makes me long for a seventh gear.

Phase One:

16/41 sprockets, 2.56:1
16-tooth front sprocket (supersprox.com, $25)
14.8 mph per 1,000 rpm (sixth gear)
5,100 rpm @ 75 mph (true speed)

The change to a one-tooth-larger countershaft sprocket from Supersprox confirmed I was on to something good. The bike felt more broadly capable, and the gearbox gave some useful choices of ratio. It was not sluggish off the line or unresponsive, thanks to the friendly torque spread of the Ninja engine. Its freeway-cruise demeanor improved significantly, with revs down a few hundred rpm.

Phase Two:

16/39 sprockets, 2.44:1
39-tooth rear sprocket (supersprox.com, $85)
15.5 mph per 1,000 rpm (sixth gear)
4,800 rpm @ 75 mph (true speed)

Now we were cooking. Freeway cruising at 70 or 75 mph had the tach needle well under 5,000 rpm, where the Ninja engine makes reasonable torque and not much vibration. And I didn't find the bike doggy leaving a stop or when accelerating in traffic—the engine has gobs of torque.

Phase Three:

16/37 sprockets, 2.31:1
37-tooth rear sprocket (supersprox.com, $85),
16.3 mph per 1,000 rpm (sixth gear)
4,600 rpm @ 75 mph (true speed)

When we went down the last two teeth in back, I was secretly hoping the Ninja would feel lethargic, so we'd know we'd found the limit. Only sort of. Top-gear cruise still improved—thanks to reduced revs—but some lower-gear snap had slipped away. Overall, this was probably going too far, depending on rider preference.

Also, with this small rear sprocket, the eccentric axle adjusters maxed out their ability to properly tension the chain. Living with this setup would require removing links from the stock chain or buying a shorter replacement, and the questionable value of the 37-tooth rear sprocket can't justify that. But now we know: Asking the Ninja 1000 to pull more gear gives it a huge dose of civility and mission flexibility. It really does get better with longer legs.

Kawasaki Ninja 1000 Doin Time
Kawasaki Ninja 1000 Doin Time
Supersprox's 39-tooth rear sprocket (along with a 16-tooth countershaft sprocket) dropped 75-mph top-gear cruising to just 4,800 rpm. Smooth.
Kawasaki Ninja 1000 Doin Time