snopro
New member
my bud is building a grass drag sled.
it is a 77 exciter or STX chassis, 44 mm flatslides and a 643 Yami motor out of an SR. he has the 643 SR pipes on it and asked me what the motor should top out at for RPM.
now, i know these motors were low revers but how high should be be reving this beast exactly for good power and durrability?
it is a 77 exciter or STX chassis, 44 mm flatslides and a 643 Yami motor out of an SR. he has the 643 SR pipes on it and asked me what the motor should top out at for RPM.
now, i know these motors were low revers but how high should be be reving this beast exactly for good power and durrability?
toydoc
Member
Make sure it has the updated 30* taper crank shaft and extra bearing block on the clutch side. Without both, the spline crank wont last very long.
Stock 73 SR 643 is 7800rpm
Yamaha GYT porting and pipes 8500rpm
Stock 73 SR 643 is 7800rpm
Yamaha GYT porting and pipes 8500rpm
snopro
New member
yeap
the motor has those exact updates.
thanks, thats what we're looking for toydoc.
he has a 102c comet on it.
the motor has those exact updates.
thanks, thats what we're looking for toydoc.
he has a 102c comet on it.