Yamaha 90 hp 2 stroke Outboard WOT ( Wide Open Throttle ) 4 blade prop

3 cylinder 2 stroke Part1 Full Throttle @ WOT . Full Trim,no "cavitation"/ventilation 37.5 knots at 5300 Rpm. ( I need a Jack Plate )
Full Throttle @ WOT,,,LOWER TILT 35 knots. Rpm, I don't recall
Yamaha Specs Recommended Min-Max RPM 4500-5500 @ WOT
for this 90 HP! I have a 70 hp 2 stroke Yamaha and it has Recommended Min-Max 5000-6000 RPM. More info further down why it is Important.

"Conventional" Loop Charged 2 stroke carburated outboard
1140cc 90 hp lightweight " 121kg " outboard engine.
Propeller, 4 Blade Original Yamaha, 13 1/4 x 18 =Very good grip in the water and planes at 2600 rpm!
It would have been impossible with a 3 blade ; )

It may go faster with a 3 blade prop but i don't think it would be that much more ,and i would lose all the benefits the 4 blade brings


One "custom modification" ...
Drilled new holes for the mounting so high that the holes for the bolts are 1.5 cm from the top of the transom
And the engine sits in the 4th hole.
Higher up is impossible without a Jack Plate.

Yamaha has four holes to mount bolts in,
If you mount the motor on the lowest holes,,,the higher up the engine will be........obviously : ) .

Lift up your outboard 1 or 2 holes
even if you drive with an aluminum propeller, it will go much easier in the water, the less rig you have in the water = the less drag

And you save fuel because of lower drag
And maybe get more speed out of the boat.

Why slow down the boat unnecessarily with a low-mounted outboard.

If you mount your rig too high The Aluminium Propeller will start to ventilate (take in air ) you can hear this clearly,
Lower the outboard one hole and test again,
Or try a Stainless prop with the same pitch.
And I can assure you that it will not ventilate (losing grip in the water).
Maybe you can raise the engine further without the propeller loses its grip.Higher Performance!!

If you have lets say a 19" Aluminium prop on And replace it with a 19" Stainless Steel , It will drop the rpm at WOT ( Full throttle ) and lose performance.
Because the 19"ss is more "aggressive"( the most ss are ) then the Alu dito
If you are going to have the engine at the same hight rpm try a 17"
If it still have lower rpm at wot,Elevate the outboard

Propeller Calculator

Important !
You must also remember not to go below or above the recommended RPM range at wide open throtte for your outboard.
Find out in the specifications for your outboard.
Warning !
Do not forget the cooling water intake, if you raise the engine above the intake, the engine can overheat.
But there are solutions for this also.

There is so much to say on this topic, so check out more on the web to learn more about Propellers.
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That's why I want my outboard higher up.
It does not loose the grip even at full tilt (Trim) and make 5300rpm
I want to reach 5500 rpm (Maximum recommended RPM) for this Yamaha 90 hp 2 stroke.

Since its not ventilate at the highest trim, It could probably be raised further with a Jack Plate

[drifter]

One of the if not THE best engines of all times

[Daphoid]

That motor sound / trim adjustment is childhood memory city for me. We had a few of them. Practical was a 40 hp on a pontoon boat. Fun was my uncle's 90 hp on a 13' fiberglass shell (no decking/bow covering - just the boat, some fiberglass bucket seats with boat cushions in them and some cut foam, and a rudimentary dash).

[Nknudsen]

i bought a 30 hp suzuki 2 stroke last year and it sanked in saltwater from a bad storm i rinse it all day with water and dry it put some new spark plugs and that´s it it ran like brand new still i love it

[uhklixzy]

just bought a 06 90. The man had it garage kept, but kept it well maintained. Very pleased with my purchase. It's a beast!

[pioneerz]

Three cylinders and two stroke, this is how an outboard should sound.

[sayaRiddles]

It pretty cool that this single 90 hp can run trough the water that fast,

may i ask waht is tonage of your Boat for this 90 hp engine and how efficient the fuel consumption is?

[reefslayer]

Great little motors, mine finally gave up and replaced it with a mercury 90 4stroke, definitely not as fast now

[connorcraw-reid]

Got the same motor and I love the rooster tails it makes

[teddyforan]

Thanks for the video getting me excited for mine 👍

[clamils]

Ciao chd differenza c'è con l 80 cv ?? Quanti nodi fa questo? Grazie

[carldalmas]

Which fletcher hull is the engine on ? 75hp 85hp 90 hp yamaha same engine difference carbs and tubes very thirsty motor three carbs v 4 115 has a lot more power and cheaper to Run! As has two carbs Etec are the way to go now

[InfoVblog]

Great Sound, I have a 2001 2 stroke 3 cylinder 90h. can only reach 5000 rpm SOMETIMES.. haha

[lordoftheriffs]

I got a 16.5 ft deepv center console with an F115 outboard, aluminium propeller 19 pitch original Yamaha. It goes 40 knots at 6300 rpm at full trim. It is mounted at the second lowest position. Motor has 5300-6300 wot range, feels fast but I think the last 400 rpms don't bring much speed. Should I go SS 19 inch?

[wilfriedxps]

J’aime beaucoup cette vidéo. J’ai le même moteur sur un bateau plus long .

Je veut essayer aussi une 4 pales !

J’ai une hélice Michigan Ballistic 13 x 15 je suis à 5300 rpm pour 34 noeuds .

Vous préférez le 4 pales ??

[dottorfoggy]

Same angine on a yamarin 5120, I have a solas 13, 5x17" aluminium but at my wot I can only reach 33 knots @4900, marsch speed at 26 knots with 4000rpm. Definitely not a good combo and I can hear that the engine is working a little bit too much, not easy to plan. Any suggestion? I still have to test a mercury 13x16 ss i have but I want a yamaha ss on next.

[diegomayan]

Best engine I had... 6k rpm on a 20" propeller.... what a beast

[achilledup]

How long can you go WOT without damaging the engine?

[sawmaster]

Beautiful sounding motor! Does the Yamaha 85 sound the same?

[HoldemHookTV]

Do you put the same oil in the oil take as the in the mix oil gas mix

[da]

I have drilled the holes for the engine as high as it will go on the boat. 
I think I need a jack plate of any kind, do you have any tips what is best.