MyChron 5 RPM setup for Rotax 125 Max

Driving, Data & Fitness.
1

I recently installed a MyChron 5 on my Rotax 125 Max powered kart and I’m not sure I have the tach / rpm settings set up properly. After a day of testing, I was reviewing data from my laps and found my min/max rpms as 8000/15900. This is well above what the Rotax should spin to, but power and performance were enough that those being double the actual rpm value doesn’t make sense either. I cannot find any information about setting up the rpm factoring in MyChron. Anybody run a MC5 on a Rotax kart who can help?

Additional info:
RPM frequency: 20hz
RPM factor: x2
Max Speed: 57mph
Gearing: 12/85
Track type: short road course, < 30 sec lap time

2

RPM factor should be x1 I believe. One spark per revolution?

3

Be aware Rotax’s have a large scondary coil bounce, and the mychron will read multiple spark events each cycle. You can cut the mychron pick wire several inches down from the clip and cable tie it back together to make the signal less sensitive.

1 Like