Rotax 912 starting rpm?
in 912 / 914 Technical Questions
12 years ago
Just an FYI for those who don't know and I hope this helps some day,
There have been many numbers thrown around for the Rotax starting required rpm. We don't have magnetos we have trigger coils. In order for these to get excited and fire current to the plugs we need a minimum of 225-250 engine rpm which translates to 92-103 rpm using our 2.43:1 gearbox ratio. Now if your battery is weak and you only get 85 prop rpm or less it won't start. You can not tell the difference looking at the prop or listening between the 93 to 85. So if your aircraft doesn't start you need to use a newer battery or jump it to rule out the possibility of a poor battery.
We have 5 trigger coils. 4 for our needed amps/voltage and one for the tach signal.
There have been many numbers thrown around for the Rotax starting required rpm. We don't have magnetos we have trigger coils. In order for these to get excited and fire current to the plugs we need a minimum of 225-250 engine rpm which translates to 92-103 rpm using our 2.43:1 gearbox ratio. Now if your battery is weak and you only get 85 prop rpm or less it won't start. You can not tell the difference looking at the prop or listening between the 93 to 85. So if your aircraft doesn't start you need to use a newer battery or jump it to rule out the possibility of a poor battery.
We have 5 trigger coils. 4 for our needed amps/voltage and one for the tach signal.
Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell
