dont think they were a large bore, we ended up using kyosho big bore springs on them (only cause i had some). we also milled out the chassis but only to let air to the motor, with 4 slots with a 45degree chamferd edge about 5mm gaps the width of the motor. the diffs were good, no bearings failed only went through 2 slippers and spur gears, 3 drive shafts in 24hrs non stop and a box full of tyres!
