A 730 mAh pack has a high internal impedance. I'd look for a low impedance NiCd pack or a larger low impedance NiMh. The 1950 NiMh packs I get from NoBS batteries only have 5 ohms per cell... that's pretty low. I lot of NiMh packs have 25 ohms per cell... that's 20 ohms total vice 100 ohms total... what's that mean? Large voltage drops when running.

Also, my 80 was a bugger to start until I re-check my timing setting... it was way off. Runs like a champ now!!!