The YS140 would be a great engine for the Rare Bear, the TT120 has the same output as the YS110 only. The TT120 will turn something like a 15x8/16x6 whilst the YS140 will turn an 18x6. If you feel a little rich then why not the YS160? Still the TT120 is a very nice engine, I loved mine a lot. Easy to tune and will start with a flick. Anyways, I seen the Rare Bear with a TT91 2C ... it flies okay ... so I think the TT120 will be brilliant.