General Hints
Read your workshop manual. The engine should be warm and running at just enough above idle speed so it doesn’t falter and stop during adjustments. Don’t try to balance at high engine speeds. Adjust to makers specification or average of initial readings, but the readings should be balanced to within 2 cmHg (some models up to 4 cmHg) of each other.

Adjust in small amounts, waiting a few seconds between each part adjustment. Write each adjustment down so you can go back to the original settings if necessary.

If lending gauges to a friend please ensure your friend has a copy of the instructions and is familiar with the gauges.



Ideally balance the throttle valves after you have serviced the rest of your bike.

A Guide to Carburettor Synchronizing
Carb balance will affect the response, smoothness, mileage, performance and running temperature of your engine.

Carb synchronisation consists of adjusting each throttle valve for carburettors or fuel injection throats so that they pass as much fuel-air mixture as all the others. This balances the load carried by each piston.

If one carb is opened further than the others that cylinder will run hotter than the others. The other carbs will also supply a richer mixture and mileage will suffer.

The actual mechanics of carb balancing vary a lot. Some bikes are balanced by adjusting the relative length of the throttle cables (R series BMWs) while others have a system of levers with adjustment screws but they all adjust the relative position of the throttle slides or throttle butterflies of each carb to each other or to a master preset carb.

A workshop manual for your model is very useful as the balancing procedure for different models can vary in detail. Familiarise yourself with the section on throttle valve synchronizing.