ODYSSEY PC545 our choice for primary battery.

Odyssey PC545 is our choice for primary battery. Since it is aft mounted did not need high temperature capability that metal jacket would provide, thus weight is only 11.7lbs instead of 12.6 lbs for the PC545 MJ. I am pretty certain on Odyssey batteries orange case is jacketed and black is not. It is touted to provide 71 amps for 5 minutes! 914 with new style starter will probably only draw 50 amps. CCA is 185 amps.
PC545 is 11.7lbs no MJ 12Ah@ 10 hour discharge rate, CCA 185Ah.
PC625 is 13.2lbs 17AH@ 10 hour discharge rate, CCA 265Ah.
PC680 is ~15lbs no MJ 16AH@ 10 hour discharge rate, CCA 220Ah.
The battery with the greatest ability to dump amps is the PC680, then the PC625 then the PC545. You can find more specs: http://www.odysseybatteries.com/files.htm
Bottom line is any of the above 3 will provide plenty of cranking amps for a Rotax. If you want light the PC545, if you want more capacity then the PC625. The PC625 has more capacity than the PC680! Unless you needed the extra cranking amps for a Lyc. or Cont., IMHO I would look very hard at the PC625. So what a PC680 can put out 680 amps for 5 seconds compared to only 625amps the PC625 can put out, kinda moot when even a 912S Rotax with old style starter will draw ~ 60 amps. AGM batteries will work with a regulator set to 13.6 or 13.7v, but would be happier at 14.7v if you can adjust setpoint.
Y9-01-01