Super Jet Bad cases ?

[stefan]

Can a pair off cruket cases doo this too a crank. The rust came after the engine was taken apart.

 

[MASSEY]

looks like the bearings did that!

 

[stefan]

Year but the crank Wash 10 monthes old and wash spinning free.

 

[john zigler]

What brand crank / bearings?

 

[stefan]

SBT

 

[Harbor]

10 month old crank, is this a repeat failure? Did this happen to the previous crank too?

 

[stefan]

I dont nov about the crank before this, just think it is weird that it brokke after 10 monthes.

 

[550/440]

10 months could be a lot of riding, or hardly any - any idea how many hours on the motor?

 

[TheBuzzard]

usually , the cage that holds the balls falls apart. your cage looks good where the pic was taken. is it good everywhere or is there a chunk missing? when you pulled the motor apart, was there any dings or damage to the piston tops? sometimes you can catch a crank going bad, if you take the head off and see very minor damage to the piston tops. if the cage comes apart and then a ball runs over it, it could bust the race like yours did. if the cases are worn out and too big where the bearings ride, it could bust also. look at the cases where the bearings ride. if it looks like the bearings walk or chatter, the cases are worn. SBT may use garbage bearings and that could be the cause.

 

[stefan]

Abut 50 hours on it, engine ran fine was moving crank too some ported cases.everyting was together till the crank was removed then the missing peice came off.