|Trying to help a friend with a bad failure on his Yamaha 60 hp 3 cyl 2 stroke (early 90`s late 80`s?)
Motor made an unusual noise at three quarter throttle. We shut it down immeadiatly
Motor was tight and hot and would not turn.
Stripped motor, found cylinder head of bottom piston to have small pit marks around edges, a piece of piston skirt broken off, the bearing on the connecting rod to crank was tight and the bottom main bearing on the crank was rough when turned. Could this have been
Cooling failure - worn impeller
Mixture setting on bottom carb - too lean
Can the experts please advise possible causes and reasons for this failure and solutions to prevent this re occuring after being repaired