Merc 90 vs Yamaha 90

ATVGUY

Recruit
Joined
Jan 30, 2010
Messages
1
I'm putting this outboard on a small boat (Humber Jewel ,12' lg and 500#) I want to go fast so weight is important and I hope to have it for a long time. The Yamaha 2 stroke weighs 261# and the Merc 2 stroke weighs 303#. I have 3 questions . Which is the better outboard in lasting longer and reliability ? Would 40lbs make alot of difference in a boat this small ? The price difference is substantial ( the Merc is $1500 less) which is the better deal ?

ATVGUY
 

coolguy147

Commander
Joined
Jul 14, 2008
Messages
2,817
Re: Merc 90 vs Yamaha 90

Mercury

buying used or brandnew?

year?

yes 40 pounds can make a difference in speed but there may be a good reason. maybe 40 pounds into reliability parts. good grade bolts and such.

i poursonally dont like yamaha.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: Merc 90 vs Yamaha 90

There is no way to say which one is better with so little information, you didn't even give us the age of each motor.
 

4JawChuck

Chief Petty Officer
Joined
Aug 7, 2009
Messages
504
Re: Merc 90 vs Yamaha 90

The 90HP Yamaha's have a whole host of aftermarket HP parts available for them and can be spun higher RPM due to their porting and rotating assy strengths. The Merc's have integral blocks and are not capable of being hopped up so easily, I wouldn't turn one over 6000 rpm for any length of time. In this HP range the Yamaha is the hotrod and the Merc is the tractor since it is higher displacement. The weight advantage of the Yamaha is quite significant, there are good reasons why the Yamaha's cost a little more money.

I own a 2003 90HP Merc and its a great motor but what I really wanted was the Yamaha until I found out how loud they are and how much of a premium they are used. If you don't plan on modifying the Motor and keep it under 5500rpm the Merc is a great motor, actually if you get a 2003 model you can buy a 75HP version and put the 90HP carbs on it and retime the motor and it then becomes a 90HP...thats all that is different between them in that year and thats what I did.

If you don't care about a little more noise and need the lightweight, the Yamaha is the one to get. For me the lower price and parts pricing of the Merc plus the fact that I had a choice of excellent condition Mercs all around to choose from meant I could get a like new Merc for $1500 less than a pretty worn Yamaha.

It really depends on whats available and how much money you have to spend and if 60pds makes a difference to your boat. For me and my 16' Tuffy fishing boat I went with the value leader...Merc. If I had a light two seater pad hull I would have spent the money and looked for an excellent condition Yamaha and insulated the cowl with dynamat so I wouldn't have to listen to it.
 

jasonbailey

Petty Officer 1st Class
Joined
Jul 25, 2004
Messages
253
Re: Merc 90 vs Yamaha 90

If you are buying new, the dealer is another critical factor to look at. I was looking both at Mercury and Yammy when I repowered last year. The Yammy dealer was offering up a better deal than the Merc, but I preferred the Merc dealer over the Yammy. I'm glad I went Merc, the Yammy dealer went belly up 3 months after I had the new motor installed.

I have the Merc 90 ELPTO, so far it has been trouble free, and so far I think it has been a good purchase.
 

BigB9000

Lieutenant Junior Grade
Joined
Dec 5, 2007
Messages
1,154
Re: Merc 90 vs Yamaha 90

My views on merc's (based on pure opinion, with no facts to support my thought)

1) A lot of very bad design flaws (the ability to get to bolts)
2) Seems like one of the cheapest engines money can buy.
3) post a question over in the johnson forums, then in the merc, and see which one gets answered.
4) Crap wiring.


Now, word on the street is a 4 cyl 4 stroke yamaha, is a ford engine block anyway.
 

4JawChuck

Chief Petty Officer
Joined
Aug 7, 2009
Messages
504
Re: Merc 90 vs Yamaha 90

I'll second that, in comparison to my old 50Hp Yamaha my Merc looks like it was built in the Briggs and Stratton factory.

I had the starter go out on it a few months after I got it home and found out it was full of water so it was shorted. Thinking I got a submerged motor I disassembled everything and soon found out the starter housing is not vented and condensation builds up inside especially if you leave it on the water for any length of time. A couple of well placed holes in the base plate of the starter housing will ensure that will never happen again but I had to question how could a company that specializes in Marine motors miss such a obvious engineering mistake. Luckily nothing was damaged and only needed a good cleaning to restore the starter motor, I lubed it up and sealed the armature in Glyptol (after having it growled for shorts) and it worked like a charm. The brushes and commutator were still like new and the motor showed no signs of ever being submerged.

Then I found the teeth on the starter ring were chipped from the crappy rubber mounting on the starter motor which was solved by replacing the rubber mounts with AL versions I made on the lathe, honestly rubber mounts for a starter? Last I found out while trying to time the motor the plastic ball ends for the timing ring lever/carb connection are so loose the timing jumps all over the place, I replaced them and sealed them in heavy silicone grease which stops them from vibrating...cheap cheap cheap.

Yamahas have that typical japanese build quality about them, my Merc looks like it was designed and built in Malaysia. Runs good though and has lots of power with decent mileage, better than the 50 HP Yamaha it replaced and it ran like a top too.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Merc 90 vs Yamaha 90

A 90HP motor on a 12' boat, seems like over-powered and over-weighted to me! Good Luck and don't get killed!
 

GeneH

Petty Officer 2nd Class
Joined
Sep 1, 2007
Messages
109
Re: Merc 90 vs Yamaha 90

The last two posts should have been the first questions asked. What is the rating of the boat hull? Check this out before proceeding! You can't just drop a 454 chevy in an 8 foot boat because it would be "cool". There are legal issues here which can't be ignored.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
Re: Merc 90 vs Yamaha 90

Not sure where you are headed. My choice is Merc BECAUSE OF the cubes. I'm running a '02 90 on a 17' BB with a dry boat wt of 700#. Crud in the boat is the normal BB load....3 batt, livewell TM, dozen tackle boxes, dozen rods, cooler and 250# of me. I'm running a 24P Ballistic prop on it and before ethanol came to be around here I repeatedly ran 50 or a tad over GPS. Now it has dropped to 48.5 with E10.

I run midrange Mercs to 6000 and have for years. My current engine runs 5600 in a straightaway, but in a tight turn that I usually do at WOT, rpm's will move up to 6000 till I straighten out and the water gets back to normal and quits ventilating. Previous engine was a 6 cyl tower at 115 hp and 6000 is where it ran and the boat it still in the family. Don't know what it runs on E10 as the son-in-law owns it now.

My 2c,

Mark
 
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