Motor swap

[WGS55]

I've got a mid late 80's boat that is in excellent condition, all except for the motor. The motor is a 1986 Mariner 90hp, but it needs help. So we have decided to swap it out for a New 115hp Yamaha 4 stroke. So here is the question: The mariner is gas oil pre mix motor (not oil injected), so there is oil residue in the tank. We will drain the gas tank and then add new fuel, will this be sufficient for the new motor, or does it need to be rinsed with fresh gas more?

 

[Chromatose]

The residual (If any after rinsing) will not be enough to effect your new motor.

 

[Irishrover]

Agree with Chromatose. I think you'll like your new motor. Yamaha build a good 4 stroke. I suspect that motor will see a lot of Billy Chinook and Simtustus!

 

[WGS55]

Thanks. Make feel better. Yes on the Lake Billy Chinook!

 

[eugene1]

That's a very nice upgrade for your boat!

You might want to run a fuel/water filter if you don't already. Seems like 4 strokes are more finicky about getting good clean fuel than 2 strokes.

 

[WGS55]

Get the boat back in the morning. And Yes, I had a fuel/water filter added. Now to get the motor broke in. Of course now the weather will turn to crap! LOL