4 Stroke Outboard Question

Model70Man · Sep 29, 2013

I have a 90hp Yamaha 4 stroke outboard on my boat I purchased in June of this year. I have run the motor through it's break in period and have just recently noticed the past 2 or 3 outings, sometimes the motor will smoke on start up. The smoke is white and it's not whole bunch of smoke. It wont do it every time I crank it up. I checked the oil and it is full. The color of the oil is darker than the oil in my truck. Is this something I need to be concerned of, or is it normal?

paincave_2000 · Sep 29, 2013

Are you sure it's smoke and not steam? Maybe try to tilt the motor 10 or 15 degrees while you fish and see if it stops.Not sure on the color difference in the oil.

Headhunter · Sep 30, 2013

from what I know, if you are not, you should be running ring free. 1 oz of ring free to every 10 gallons of gas.

rsimms · Sep 30, 2013

You are supposed to do an oil change following full break-in period (20 hours). Have you done that?

I have exact same motor. I have never noticed any smoke (or steam) whatsoever?

There may have been a little, but again not enough for me to ever make note of it. I didn't on my last 4-stroke, but on this one I have made a point to ONLY use 100% gas (no ethanol).

Headhunter · Sep 30, 2013

I did not have an oil change until a year later after I got mine brand new and it is ran a lot. Not sure about that.

If you run no ethanol gas or gas with ethanol, run one or the other, do not mix them up.

Ring free is important with the ethanol gas, not sure about gas without ethano.

farside · Sep 30, 2013

I have Yamaha 75 which is basically the same engine. When I purchase engine it was required after the break in period that I take the engine back to the dealer and they preformed a checkup and changed all the oil, filters and other fluids The service was part of warranty package at no cost.

Model70Man · Sep 30, 2013

I only use ethanol free gas. I have not had the oil changed yet. I will get that done tomorrow. The weird thing is it doesn't smoke all the time on start up. It only smoked once last time out. The motor doesn't have any leaks that I can see.