75 merc or 90 yammi????

[BigHead28]

I have a 16ft phantom that i am racing and im trying to decide if i want to use a 75hp mercury 2-stroke or 90hp yamaha 2-stroke. Which is the better motor? And if this helps i am going up against a 90hp evinrude. I would also like to know any modifications that can be used for both.

[Maple Leaf]

90 Yamaha! Can't really mod the Merc. No heads etc

[Rigaud]

Yamaha hands down and easy to get more hp's. Contact FastFred from this site.

Also get in touch with these guys.

http://www.hydrotecmarine.com/

[AnthonySS]

Go for the 90hp (better then the 75) merc...loved that motor (1988) and really did not have to mod the engine to get good power out of it. just did some bolt of stuff and removed stuff and would push this 16'-5" Vision into the low 60s with 26 small blade chopper at 6400 rpm...all day and cheap on fuel...it was a great engine...

I would love to find that motr...the gearcase is about a hydro dynamic as a fist...so look at that as potential mod...the XR xones fit on them

[FrenchPhil]

Go for the 90, lots a mods for it. UIM offshore record is over 77mph (cat).

[Jason Johnson]

HHHHUUUUMMMMMM what a choice

[Rigaud]

Sorry Jason, I should have mentioned you as well since your quite the guru with the small Yam's. :thumbsup:

[BigHead28]

I don't know if I was seeing things but I believev I saw a 90 hp yammi with a sport master gearcase and bellmouth carb attachments. Does anyone know what I'm talking about?

[AnthonySS]

Yeah it would have been interesting to se how the 90 merc ran on real race hull. We often did compete alongside them but often came second. Not bad considering it was on a 725 lb full interior hull. Of course the cat' sass would have been the SST 90.

[Jason Johnson]

Big head, I really think that I saw that too. I even PM-ed the guy and asked him for more pictures and he sent me a link to a you-tube vid of a knee down hydro.

Anthony, what speeds was that 90 merc doing. We have one here bone stock that is at 63+ mph right now. I wish the head was removable, I'd have both elbows in that baby. Thats what I love about the Yammi, speaking of which, it's fixing to go under the knife again.

[AnthonySS]

2.3:1 gear at 6400 max with the 26 wheel...also put us into the low 60s...I agree on the power head...that's why it would be good to find an SST 90 PH....ENJOY and good numbers on ya :)

[FrenchPhil]

It was a 2:1 gear ratio

[M. HARDEE]

Yammy the way to go

[David]

Anthony, long time no see. I did not know you had a 90 on your Vision before the 150. What are you running now?

As for the post, 90 Yamaha vs 75 Merc is easy, go with the 90. Buying used 90's, I'd go for the one in the best condition. On a smaller boat, the lighter weight of the Yamaha would matter.

[AnthonySS]

My 90hp Merc was 1988 3 cyl so it was 2.3:1...i think the inline6 90 was 2:1.

Again an SST 90 PH would be SWEET exactly 1/2 the displacement (1165cc) of a 2.4 (2330CC) of the day...coincidence?

David.. Nice to hear from you...yes we had the 90 on the Vision up until 1992. It was actually a sweet setup for what it was and drove very nice...the Vision with the XR2 was simply WILD.

We have had STV RR for the past 3 seasons. Pix on STV owners

[AnthonySS]

XR on Vision

[Hounddog]

You also have some other interesting part options with the 90 yamaha. You can use parts from the 48 to 60 Hp Mariners and 55 hp Yamahas.
The 15 inch mid on the 90 Yamaha in a previous post is from a 48 mariner.
There is also a 19 inch mid from these motors so you do not need to use the 90 hp long unless you want it.
Also there are 2 inch spacers for these mids, so you could even have a 17 inch if you wanted.
I have also seen a 12 inch, but can't get the part number.
The gear case also fits and you can get 1:86 or 1:71 ratio's. You do need to made a drive shaft fitting because of the different sizes. The water pump pumps enough water. This is a small gear case and you can run smaller diameter props.
The engine mods can be wild or mild. We did a mild one. Hydro-Tec dyno numbers were 119.4 hp at 6500 rpm and 101 hp at 7500 rpm. This is on pump gas with 150 lbs compression.
Steve Cooler and Ernie Brown did wild ones and are in the 130 hp range.

[Jason Johnson]

Houndog, all so true. I would love to know how much power my 90 is makeing? I have a freind that had a 14' Vandal with a stock 115 Yammi. w/t LWP. I could out accelerate and pull him on the big end by about 5mph. I would think that mine is makeing good horsepower, just don't know how much. I have about 6 more things to do to it, and mine was built from junk parts. Not a good tight motor.

AnthonySS, if a person was to find a 90SST, No one in the world would sell it, I am a Yamaha man and If I got a 90SST I would hang on to it also. I wish that "That" racing was still here today, it would be nice to redoo all the rules for those classes to make it to where one could run any manufacturers inline 3 cyl, Yammi 90, OMC (60SST), Merc 90, Tohatsu 90, Nissan 90, and get it all evened out, fair.

But getting back to the original question, A 90 Yamaha is just such an easy choice. Abundant, light, Very easy to mod, parts by the sackfull, and as stated above the combinations are plentiful. One other thing is economy, mine is so cheap on fuel, its crazy.

[BigHead28]

So the main place to look for parts for yammis is hydrotech marine??

[Jason Johnson]

You can do it all local at a machine shop, What do you have in mind?

[BigHead28]

There are so many options. What do u recommend or what do u have for yours?

[twright55]

What's the difference between the 85 Yamaha and the 90? I am seeing a number of 85s for sale, but not 90s.

[chipg]

Did the 48s generally come as a 19" including the 2" spacer? I have found part number 697-45111-13-4D below the pic appears to have a spacer for the mid, but unsure if the mid is 19-20" with the spacer, or if the spacer is in addition to a 19-20" mid.
http://parts.yamaha-motor.com/partimage.gifx?d=81871,2,0,outboard



You also have some other interesting part options with the 90 yamaha. You can use parts from the 48 to 60 Hp Mariners and 55 hp Yamahas.
The 15 inch mid on the 90 Yamaha in a previous post is from a 48 mariner.
There is also a 19 inch mid from these motors so you do not need to use the 90 hp long unless you want it.
Also there are 2 inch spacers for these mids, so you could even have a 17 inch if you wanted.
I have also seen a 12 inch, but can't get the part number.
The gear case also fits and you can get 1:86 or 1:71 ratio's. You do need to made a drive shaft fitting because of the different sizes. The water pump pumps enough water. This is a small gear case and you can run smaller diameter props.
The engine mods can be wild or mild. We did a mild one. Hydro-Tec dyno numbers were 119.4 hp at 6500 rpm and 101 hp at 7500 rpm. This is on pump gas with 150 lbs compression.
Steve Cooler and Ernie Brown did wild ones and are in the 130 hp range.

[Jason Johnson]

that is the 15, order 3 of them :D

[ROLF]

Jason,you have a PM.
Rolf

[chipg]

They show them to be under $300, but who actually has one in stock?


that is the 15, order 3 of them :D

[BigHead28]

I want to thank u all for the advice... Sadly when I raced this weekend the fuel connector to the motor wasn't the right fit so not enough gas was gettin to the motor. So I had low rpms and couldn't go fast.

[Jason Johnson]

I had a little spell of bad luck too this weekend, put up some pictures of your rig, we would love to see it.

[BigHead28]

Will do. Its jus not some detail pics but overalll specs. I'll have them up later this week. Went so hard foot throttle came out of floor.