Innovate Motorsports ST-12 - Manual (Page 17)

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2. Odd fire engines, like V-Twin motorcycle engines and odd-fire V6 engines have ignition pulses
that are not evenly spaced. For example a 60 degree V-Twin running at 10 degrees ignition
advance will fire cyl. 1 at 10 degrees BTDC. Then fire cyl. Two 420 degrees later at 410 degrees.
Then fire cyl 1 300 degrees later at 710 degrees. This means the ignition pulses sent to the ST-12
are alternating between 420 and 300 degrees apart and therefore the time between pulses
alternates. The ST-12 therefore measures the times between ALL pulses for a complete engine
cycle (2 rotations) and averages the times between them.
5.2.7 Programming the RPM input
- Determine the number of ignition pulses per crank rotation. Refer to Table 2 or 3 for guidance.
- Press the ‘Channel’ button until it shows channel 1.
- Press the ‘Function’ button until it shows 1 or 2. Use 1 if your engine’s redline is below 10000
RPM. Otherwise use 2.
- Press the ‘Calibrate’ button until the selected Cyl. Number appears
Table 2: Cylinder number and RPM calibrate number 4-stroke engine
Number
of
Cylinders 4-Stroke
pulses/Crank-
Rotation Calibrate
Number Comment
1 1/2 1 Use also when using inductive
clamp on spark wire or power wire
of COP system of 1 cylinder only
for all cylinder numbers
2 1 2 Use also when using inductive
clamp on spark wire or power wire
of Waste spark coil of 1 cylinder
only.
Waste spark system:
1 coil for every 2 cylinders.
3 1-1/2 3
4 2
4
5 2-1/2 5
6 3
6
8 4 8
10 10 A
12 12 C
Table 3:: Cylinder number and RPM calibrate number 2-stroke and Rotary Engine
Number
of
Cylinders 2-Stroke
pulses/Crank-
Rotation Calibrate
Number Comment
1 1 2 Use also when using inductive
clamp on spark wire or power wire
of COP system of 1 cylinder only
for all cylinder numbers
Also use for rotary engine.