Yamaha Four Stroke Outboard Service - Oil Change, Lower Unit, Spark Plugs

We're going through the oil change, lower unit lube change, and replacing spark plugs on this Yamaha 50 hp four stroke outboard today. The process will be very similar for most Yamaha motors, with slight differences between the horsepower ranges.
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[@kenfendler506]

Thanks for the tips. I'll be doing the same on my 75hp Yamaha.

[@tomspontoons]

Happy to help! Best of luck with your project.

[@upice3]

Very Helpful...nice pace in video. Appreciate it :)

[@tomspontoons]

Thanks for the feedback, and for watching!

[@tritownnow]

Well done Tom. If get the opportunity to come across a 2004 90 hp 2 cyl Mercury, a video of winterization would be great. I like how you have a full spectrum of videos, from a stripped down pontoon, rebuilding from the hood bones of the structure, add in a new floor, furniture, new fencing, electronics, and now to engine maintenance. You have the makings of a one stop pontoon DIY channel. For a DIYer, Thank you for that!

[@tomspontoons]

Thanks so much! And thank you for your contribution to the channel. We’re about a year in to our channel and building content…there’s infinitely more to cover!
If your 90 Mercury is a carbureted two stroke I would simply run stabilizer in your fuel through the motor, advance your throttle slightly at the end and spray fogging oil into the intakes of the carburetors. I will try to make a video of this style of fogging an engine in the future! From there your lower unit gear lube is the same as this Yamaha.
If your motor is an Optimax I would simply run stabilized fuel through, change the lower unit lube, and call it good!

[@tuiflies5869]

My understanding is that the hash marks on the oil dip stick are an operating range indicator. Not a full/add indication. Anywhere in the hash marks is good.

[@tomspontoons]

Correct. I aim for 3/4 to full when doing an oil change, that way once the motor has been started and oil moves through the filter and crank case it will still be 1/2 to 3/4 full.

[@michaelcook727]

Thanks!

[@tomspontoons]

Thank you SO SO much!!

[@DaSween]

Hey Tom. Thanks for the awesome videos! I like how you mentioned to use a big flathead for the lower unit screw. A tip I learned from my dad is to use the flathead side of a tire iron. It’s big and tough and gives you leverage to back that screw out without stripping.

[@tomspontoons]

Thanks for watching and the kind words. Nice tip for folks at home with that tool laying around! Bottom line is we’re bound for trouble if we try to use a standard screw driver!!

[@DaSween]

@@tomspontoons you got it! Hey, I’m also wondering, do you have another business as well? Sometimes in the background I see a bunch of bundles of pipe in the background, or do you share space with another business? Never the less, that’s a sweet building and I would love to have that much space!

[@tomspontoons]

@@DaSween we own an online fitness business, as you may have seen the little gym in the background. The pipe is not ours, it’s a subleaser.

[@kanauiobuna9890]

Very helpful

[@tomspontoons]

Glad to help! Thanks for watching

[@ProgramsAaronB]

I have the same engine and it has started bogging down when accelerating. I replaced the fuel filter and it still isn't working. Do you think this could be the spark plugs?

[@tomspontoons]

Definitely could be, but usually you want to start with your fuel. Test it where it’s pushing into the motor to check for water (clear bottle and let it rest and separate if there’s water). It’s the most common issue for the newer four stroke EFI motors. Especially on pontoon boats with the fuel tanks in the transom.

[@Dan-qt7kq]

At 18:12above your ring finger, a S/S thing with a bolt. My 60 hp Yamaha leaks some water out of all four when motor is running. ? Normal.

[@tomspontoons]

Definitely not normal. Likely needs a new gasket.

[@Dan-qt7kq]

@@tomspontoons but all four are identical. What are they, a relief valve of some sort.

[@tomspontoons]

@@Dan-qt7kq I'm not sure we're looking at the same thing. I'm looking at the square plate with four bolts, which appears actually to be the fuel pump...definitely shouldn't have water coming out of that. Otherwise, head over to www.vanssports.com and pull up a schematic of your motor year and hp. They have full parts schematics so you can chase down the part you're talking about and see if there's more to it. One thing I do know is that nothing should be leaking ANY water under the hood of your motor.

[@jimbolowe6076]

Could. It be more helpful. Thx a million

[@tomspontoons]

Happy to help!