The quartet of carburettors used by a Suzuki GSX-R contribute to the machine's high-performance capabilities, but only if they are kept in working order. The carburettors rely on a steady vacuum that is generated by the motor. A small change between the each carburettor's throttle valves will affect the vacuum levels, disrupting the synchronisation between the carburettors and causing a loss of power throughout the RPM range. Re-synchronising a GSX-R's carburettors is a relatively straightforward task. However, a manometer, which measures the vacuum levels of the carburettor using mercury-filled gauges, is required for the job.
Place your GSX-R on a service stand to provide a stable support. Place a large fan in front of the motor. You can leave the motorcycle on its kickstand if you do not have a stand.
Remove the side fairing panels from your GSX-R, using a 4mm Allen wrench. Start your GSX-R's motor and let it warm up for three minutes, then stop the motor.
Remove the inlet screws from the back of the carburettors, positioned just forward of the motor's intake manifolds, using a small flat screwdriver. Screw your manometer's adaptors into the carburettors' inlets. Plug your manometer's vacuum hoses into the adaptors.
Start your GSX-R's motor again and turn on your fan to prevent the motorcycle from overheating. Adjust the motor's idle speed to 1,750rpm, using the idle adjustment knob on the left side of the motor.
Take note of the manometer's vacuum measurements between the motor's #4 and #3 carburettors -- positioned on the left side of the motor. The mercury levels for both cylinders should be evenly balanced in the centre of the meter's gauges. If the levels are not identical, turn the adjustment screw between the #4 and #3 carburettors with a small flat screwdriver until the vacuum levels are even. Balance the #2 and #1 carburettors bodies on the right side of the motor, using the same method.
Synchronise both carburettor banks, using the adjustment screw placed between the #2 and #3 cylinder. Turn the adjustment screw until all four carburettor's vacuum levels are centred in the meter's gauges.
Adjust the motor's idle speed to 1,200rpm, using the idle adjustment knob. Stop the motor and reinstall the side fairing panels, using a 4mm Allen wrench.
Things you need
- Service stand
- 4mm Allen wrench
- Manometer with threaded adaptors
- Flat screwdriver