These dials really help you track the performance of your engine and make precise adjustments. The difference between the "Sport" and "Race" dials are:

"SPORT" After a base tune is dialed, loosen the set screw and
Rotate the Dial until the HSN Reference Point aligns with "3"

Snug the set screw.

When making tuning adjustments, the tuning direction is easy to remember. The higher the number = more fuel (rich) and the lower the number = less fuel (lean). This "starting point" is only an average from engine to engine. Ideally the tuning distance to
"0" is for leaning out the engine to produce maximum power. Turning the HSN all the way to "0" is set to be the upper limit for engine performance and temperature.

Use the tuning dial to record and track HSN settings.

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"RACE" After a racing or base tune is dialed, loosen the set screw and Rotate the Dial until the HSN Reference Point aligns with "0"

Snug the set screw.

As running conditions change, controlling engine temps and performance with exact needle adjustments are more manageable. Use the +/- signs for decisive adjustments for a rich or lean fuel mixture.

Use the tuning dial to record and track needle settings.