Just cracked a powerhead and looking for advice. Bought motor used 18 months ago-well maintained, knew the owner, less than 600 hrs on engine etc..Warranty ran out last May. Cause unknown yet but starboard middle cylinder had piston/rod failure. Leaned out due to bad O2 sensor or water? - or maybe carbon???. Is this common with these models? I just heard about two others letting go with a similar problem. Trying to decide whether to rebuild now or repower with 4-stroke (one day in the future). Don't want to rebuild if there is an inherent problem. This is second Yamaha to let go 
in two years (had an '88 225 Yamaha Excel that burned a piston due to oil pump failure and no alarm). My research on the 250's showed them to be very reliable. Any comments are sure appreciated.
in two years (had an '88 225 Yamaha Excel that burned a piston due to oil pump failure and no alarm). My research on the 250's showed them to be very reliable. Any comments are sure appreciated.