Gearing advice on a b4.1

[Redkite]

hi all,

just trying to get my head round gearing etc - got an old b4.1 stealth chassis and I put some new old stock RTR XP electrics in it - a SC450 esc and a reedy 3900KV motor with a 4000lipo battery - currently on a 81 spur and a 24 pinion - seems quick and not too hot running... its a basher at present.

can anyone tell me that brushed equivalent this motor is please and suggest any good gear ratios to use etc - it drives very nicely !

cheers

paul