most stock Yamaha R6s make roughly 100–115 WHP, with individual dyno pulls commonly showing anywhere from ~95 WHP up to ~120 WHP depending on year, dyno type, and condition. Wikipedia+2MotoStatz+2
Why that wide spread (quick bullets):
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Yamaha’s published peak-power numbers and how they were measured changed over the years, and some spec sheets quote crank or “ram-air” numbers rather than measured rear-wheel power. Wikipedia
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Real-world dyno pulls for R6s commonly land around ~100–110 WHP, though clean engines and favorable dynos sometimes show 115–120 WHP and tired/untuned bikes can be in the high-90s. MotoStatz+1
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Simple bolt-on mods (exhaust, airfilter, ECU flash) usually add ~5–15 WHP at the wheel; big internal mods or race builds add more. Forum/dyno threads back this up. r6-forum.com+1
Example — how to estimate from a claimed crank number:
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Suppose a spec lists 120 hp crank. A common rule-of-thumb is ~10% drivetrain loss to the wheel.
Calculation (digit-by-digit): 120 × 0.10 = 12; 120 − 12 = 108 WHP.
So a 120-hp crank figure often corresponds to about 108 WHP on many dynos.
How I’d tighten the estimate for your bike (no need to do this now, just FYI): tell me the year, whether it’s stock or has a slip-on / full system / ECU tune / intake / internals, and whether it’s a track/race setup — I’ll map that to a likely WHP range and cite dyno examples.