The red line is correct stagger and the light blue line is with
the stagger that Yamaha supplied the bike with. To diagnose, use your EC997 Eddy Current Dynamometer and
integrated 4 Gas EGA to inspect overall CO% numbers for roughly correct
numbers and then, inspect residual O2% for excessive values. If the CO% is
good, but the O2% is high, then the stagger is absolutely incorrect and
needs to be addressed for best power. Bikes that have incorrect stagger will often pass through a dyno test
on an inertia dyno without a hitch or a hiccup. Even with an "air
fuel ratio" sensor (a simple, very expensive O2 sensor with increased
range that extends up to places where the engine doesn't even run) attached, the average reading of only one gas
(residual oxygen) still looks just peachy on an inertia dyno. Send the guy
away - you think you did a great job - you just aren't sure why his bike
seems low on power as compared to others. Maybe it's the pipe? It's the
weather, yep, that's it... To properly diagnose incorrect stagger, you need to do Step Tests with
the 4 Gas EGA EC997.
You NEED the 4 Gases.
Main jet stagger">
Main jet stagger, effects and diagnosis
If you ever wondered what improper main jet
(or fuel injection) stagger does to horsepower, here is an example.
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