90 hp yamaha blown piston

[fingershooters]

I have a 1989 90 hp yamaha motor. I rebuilt it last year. Put about 25 hours on new parts. Runs great. This weekend I took it out again. Ran through 6 gallon gas. I was running at 3800 rpms when the engine sputtered. I shut it down and switched tanks. Its started back up started to go but died. Pumped the bulb again. Started up but would barely get on plane. Ran a little more then died. It siezed. I took a cresent wrench and turned motor and then started it real quick. Ran a little above idle back to dock. Removed head and found top piston burnt. Checked carbs and they were spotless. Removed oil lines at carb and there was no oil right at end of line. Turned system over and nothing came out. Oil tank was full and went down with the 6 gallons of gas I burnt that day. What caused no gas or no oil. How can I tell. I think of removing oil pump lines and using premix after rebuild

 

[Mas]

Re: 90 hp yamaha blown piston

I do not have an oil injected motor, but if I did, I think I would always be afraid that it would fail and smoke my motor. Pre-mixing is a slight pain, but I know if the motor is running, it's getting oil. I'm no help, but sorry to hear your pain.

MAS