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8. Setup
a) Engine Fine Tuning
After the run-in phase of the engine, you may start the fine tuning process to increase the performance. To that effect, optimize the mixture for idle speed and
change-over at the idle speed mix adjustment screw and the main jet needle at full throttle.
Adjusting the main nozzle needle (full throttle mix)
• Let the engine warm up.
• Drive the model as usual.
• If the engine runs 'too fat', tune down the mix by twisting the main nozzle needle inwards by 1/16th of a turn until you have achieved the desired setting.
• Make sure that the mix is not too thin. A light white trail of smoke should always be visible coming out of the exhaust pipe.
Adjusting the idle speed mix adjusting screw
• Start the engine and adjust the main nozzle needle as described.
• Reduce the speed until the centrifugal clutch does not engage anymore and the wheels stop turning when you take the model off the ground.
• Leave the engine running at idle speed for approximately 10 – 15 seconds.
• While you are holding the model, drive at full throttle once briefly and strongly.
Make sure not to touch any moving parts!
• If the engine stalls as soon as you run at full throttle, the idle speed mix is too lean.
• Enrich the mix by unscrewing the screw by 1/16 rotations while the engine is switched off.
• Restart the engine and repeat the procedure until the speed transition from idle speed to full throttle is soft and spontaneous. A small delay in response is
normal.
• If the engine smokes strongly during transition from idle speed to full throttle and sounds very rough, then the mix is too rich.
• Make the mix thinner by screwing in the screw by 1/16 rotations while the engine is switched off.
• Restart the engine and repeat the procedure until the speed transition from idle speed to full throttle is soft and spontaneous. A small delay in response is
normal.
• Drive the model as usual in order to get a feeling of how the engine reacts to load changes.
• Modify the settings until the performance meets your expectations.
When you have carried out these settings, a readjustment of the throttle stop will also be necessary.
Adjustment of the throttle stop screw (idle speed-adjusting screw)
The idle speed adjusting screw regulates the idle speed via the position of the throttle valve (the throttle stop).
• The higher the carburettor throughput, the higher the revolution speed.
• Turning the adjusting screw clockwise increases the throughput.
• Turning anti-clockwise permits the slider to retract further and thus reduces the gap.
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