Before you start

Spark is an educational estimate only. Real maps are dyno- and knock-sensor calibrated. Too much advance holes pistons. Do not flash this number into an ECU without a wideband, knock detection and a load dyno.

Spark is a Pro tool today. Without Pro, the Spark card on the hub opens the Pro page.

1. Choose the engine

• Pick a Preset (for example Honda CBR1000RR-R 2020+, Yamaha YZF-R1 2015+, Kawasaki ZX-10R 2016+, BMW S1000RR 2019+, Aprilia RSV4 1100, Ducati Panigale V4) or Custom / blank.
• Set chamber/plugs, bore, stroke, compression ratio, cylinders and redline.
• Pick fuel (pump 87–89, 91 or 93 AKI, race 100+ or E85), octane and stoich AFR.

2. Set the operating point

• Move engine speed and throttle position, then set AFR, intake air temperature, coolant temperature and baro.
• Boost is added on top of naturally aspirated manifold pressure. Leave it at 0 for stock NA liter bikes.
• Safety retard is subtracted from the recommended number.

3. Read the estimate

• Recommended timing in °BTDC, with the MBT estimate and the knock-limited value.
• Burn details: CA50 target, 0–50% burn, laminar and turbulent flame speed, piston speed, compression temperature and pressure, equivalence ratio.
• Timing vs RPM at the current throttle, and the RPM × throttle map. Click a cell to jump the sliders there.
• Download CSV map saves the map. Reset to preset starts over.

How the model works

The app aims for peak cylinder pressure about 14–16° after TDC (CA50 near 8–10° ATDC). Higher rpm generally wants more advance, and higher load wants less. Compression, intake temperature and AFR set flame speed, and octane sets a knock-limited cap below MBT. Its numbers won’t match a flashed OEM map cell for cell.