About Airshifters

What is an Air Shifter?

An air shifter is a device that uses compressed gases to move the shift lever of an engine. Common in drag racing modern air shifter systems allow the rider to upshift without needing to back off the throttle or use the clutch. This is accomplished by electronics that control the movement of the shift lever in time with a power cut of the engine.


Air Shifter versus Foot Shifting

Part 1: ShiftFX Drag Bike Pulls Away

Dynamometer Setup
Date: July 17, 2009
Temperature: 27°C(81°F)
Motorcycle: 2008 Kawasaki ZX14
Shifter System: ShiftFX Drag with Nextup Controller
Shifter Set-up: Vortex Rearset with Reverse (MotoGP Style) Shifting Pattern
Engine Kill Times: 1st - 60ms, 2nd - 40ms, 3rd - 30ms, 4th - 30ms, 5th-30ms

Turn your speakers ON to hear the shift times

Part 2: How Can The Same Bike Go Faster?

Dynamometer Setup
Date: June 8, 2005
Temperature: 18°C(65°F)
Motorcycle: 2004 Honda CBR600 F4i
Shifter System: ShiftFX Platinum with manual overrides
Engine Modifications: None
Exhaust System: Hindle Ti Slip-on


ShiftFX Power vs. Time Power vs. Time Overlay
ShiftFX Power vs. Time Power vs. Time Overlay

Results Explained

The objective of these tests were to accelerate the motorcycle as fast as possible. Two runs were done back-to-back on the same motorcycle from 2nd to 6th gear. The results show ShiftFX bringing the motorcycle up to speed faster than manual shifting.

ShiftFX changes gears faster. This helps accelerate the motorcycle in two ways. The time saved between shifts is spent in gear, accelerating. This result can be seen on the speed vs. time graph. The second advantage is because less time is spent coasting during a shift the engine drops into a higher RPM and a better point on the power and torque curve. This can be seen on the Power vs. Time Graph.


Fuel Cut versus Spark Cut

A power cut is essential to making a fast upshift. The power cut can be accomplished by cutting fuel and/or cutting spark (aka ignition) to the engine. For carbureted engines there is no easy way to cut fuel so spark cut is the preferred method of cutting power. For fuel injected engines fuel cut is the preferred method of cutting power.

There are several reason why cutting fuel is preferred over cutting spark. When cutting spark the air and fuel continues to enter into the combustion chamber through the intake valves. In the absence of a spark the air fuel mixture behaves like an overly rich fuel mixture that can foul the spark plugs. After the air fuel mixture exits the combustion chamber it passes into the exhaust system where is can ignite and back fire. In extreme cases back fires can damage both the engine and exhaust system. Unburnt fuel can also damage catalytic converters, which are becoming standard equipment on most motorcycles.

All bike-specific Nextup Drag Kits ship with OEM plugs that connect to the bikes fuel injectors. The plug-n-play harness is recommended for all applications except when the motorcycle has been fitted with a wet nitrous system.