Fast Throttle Tube for Triumph motorcycles installation instructions.

Tools Required

Bench vice, Allen wrenches, socket set, combination wrench set (spanners), Phillips screw driver, small size hack saw, Ideal brand Stripmaster #45-091 wire stripper (or equivalent), Snap-on brand #86CF side cutter pliers (or equivalent), safety glasses, and grinding shield.


Modify the cable ends inside the throttle housing, install the Fast Throttle Tube, adjust the throttle cables. Please read the instructions completely before beginning work.

Remove the throttle housing and throttle cables

Remove the seat, fuel tank, and air box to access the throttle bodies. Take careful note of the throttle cable location and routing. At the throttle housing side: Loosen the cable adjuster. Peel back the sleeve to access the adjuster and loosen the locknut. Turn the adjuster to approximately center of the adjustment range. At the throttle body side: Loosen the lock nuts on the outside of the cable holder then push the cables towards the throttle body, loosen the nut on the inside of the cable holder. Remove cable ends from throttle body. Remove the 2 Phillips screws retaining throttle housing. Remove the housing and throttle cables.

Modify cable ends

Modify outer housing

Both throttle cable housings will be shortened to match Image #1 by cutting next the two plastic posts that hold the cables apart. Note that failing to cut enough will cause friction with the Fast Throttle Tube cam flange, a small amount too much is not a problem, and that removing an excessive amount will cause the cable to track poorly.

Secure the cable end in a vice. Use a hack saw to cut the plastic housings on each cable end approximately 90 percent of the way through, then use the side cutter pliers to pry the portion to be cut off away. Use side cutter pliers to remove any cut off pieces retained by the cable. Place the jaws horizontally on the wire with the jaw angle facing up, apply slight pressure to grip the cut off piece, bend the cable away from the cut and apply cutting force. Caution: The cut off piece may fly at your face, wear safety glasses and grinding shield.

Modify inner sleeve

Use a wire striper to remove the protruding portion of the inner sleeve. Place the sleeve in the 16 AWG slot and hold the upper section that normally separates to strip the wire together with one hand while actuating the handles with the other. This will cause the blades to cut the sleeve without pulling on the cable. The 16 AWG slot is small enough to cut the shield but large enough that it does not cut the cable. Be certain that you have the cable correctly aligned in the 16 AWG slot before applying cutting pressure. Use side cutter pliers to remove the cut off pieces as described above. Caution: The cut off piece may fly at your face, wear safety glasses and grinding shield.

Thoroughly inspect the cables. If the wires are nicked or cut they MUST be replaced. Operating the motorcycle with damaged cables may cause a crash.


Install throttle cables at the throttle bodies. Leave the adjusters loose. Check for proper cable routing. Install the lower cable (throttle closing cable) in the oblong hole of the Fast Throttle Tube. Place the cable end in the lower housing and position it on the handlebar. Be sure that you have routed the cable on the cam flange of the Fast Throttle Tube correctly before inserting into housing. Install the upper cable end in the Fast Throttle Tube. Align the cable tabs and bosses. Place the top throttle housing cover on. Install screws. Check again for proper cable routing.

Adjust the cable length

Adjust cables at the throttle bodies. As a starting point, tighten both adjusters until slight resistance is felt in the adjusters then loosen 2 full turns. Make the final adjustments at the adjuster on the opening cable near the throttle housing.
Test by turning the throttle to full open position and releasing the grip. It should snap closed fully, smoothly, and quickly. Continue to turn clockwise 1 turn and testing. When the throttle closes smoothly test for free play. The throttle cable should have free play of 1.5 to 2.0 mm (measured in terms of rotation of the grip) in all steering positions. When finished, tighten the locknut and replace the sleeve.


Rotate the throttle grip several times. Throttle grip operation should feel smooth and the throttle spring should return the throttle to the closed position when released. Start the motorcycle in riding position with the transmission in neutral. Turn the handle bars from lock to lock. The engine idle speed should not change with handle bar position. If idle speed changes by moving the handle bars the throttle cables are too tight.

Image #1