Merc 90 hp performance upgrades?

[fastleeboat]

what kind of performance upgrades are available for 90 hp outboards?

[Markus]

Not much you can do with the 90 hp Merc due to its design.

A 90 hp Tohatsu or Yamaha is the way to go.

[Capt.Insane-o]

It's a LOT of work but 2.5 style sleeves can be made and put in. The scream like a banshee, but the crank and heavy flywheel do not get along very well after awhile.

[fastleeboat]

Thanks for the info guys. Hoping maybe some hi compression heads or carb upgrades were available.

[njj502]

If it's a 3 cylinder it's already a hopped up 75HP. You'd be better off leaving that motor alone and putting it to good work on your fishing boat and hot roding something else.

[fastleeboat]

lol, my fishing boat is running 52 mph gps with this 90, and yes it is a 3 cylinder

[ChrisCarsonMarine]

we make a glass reed set for your motor that will improve its performance,and effeciency,chris

[njj502]

Your running good with it then. Dad has a 75 on a big HEAVY plate/jon boat. We got it 10 years ago with about 10hours on it. Have yet a single major issue. Have cleaned carbs once (need to again) and had one wire issue (cowl broke it). Other than that it's been bulletproof even pushing mud from the duck blinds!!!

[fastleeboat]

My boat is a light 15.5 ft fiberglass hull. It has a center console cockpit in the style of an Allison, most people that see it call it a "baby Allison"...lol It is a one of a kind boat built by a builder in Molino Fl. I just feel the boat is a 60mph boat!!!!

[fastleeboat]

Chris, I'll give you a call........thanks for responding......tony

[jeff dunn]

These motors have a low gear ratio , so that kills the top end speed . Most guys in my area that are running a boat very close to what you have are running 22 and 24 pitch laser props that have been worked, and seem to work well, most are geting 55 to 60 mph out of them. Jeff

[ChrisCarsonMarine]

Give me a call,you'll like the reeds and they won't break the bank,chris

[fastleeboat]

your right jeff. I swapped out the 2.33 for a 2.07 lower. I was turning a 26 laser about 5800 rpm's with the 2.33 @ 51 mph. with the 2.07, I dropped down to 5000 rpm's still at 51 mph. I was expecting this, but my thinking was to keep raising the motor and the rpm's and top end would increase. what happened was I lost bow lift big time!! I had to lower the motor back down and I ended up about a half inch above where I started. I'm running a 24 laser now @5250-5300 rpm's @ 52mph. lol, I spent about 1500 dollars for 1 mph. Anyway, the boat is a blast to drive and I will keep trying to ease it up to 60 mph hopefully!!!

[jeff dunn]

Have you got a jackplate on your boat? If not need to start with a 6 inch setback .Jeff

[fastleeboat]

yes, that's what I have. 6 inch setback

[fastleeboat]

I wish I had put a 10 inch on the boat, I see where it would help now...........

[JP Love]

I run 55 speedo with mine..

[njj502]

So we know that the carbs and timing are different between 75/90 3 cylinders. I found the carb numbers are WME-17=75HP and WME-19=90HP. I know the timing is a couple degreed more advanced for the 90 and that the MAXRPM is a bit higher as well. What else am I missing?

[sharkbite]

hi all, i have a 16ft phantom with a mariner 90, with a 10" setback. i used a 141/2x26 tillman prop and we get 62mph on gps. took two years to find that speed, using solid top and bottom mounts is what made the biggest difference, it stopped the motor from moving all over the place

[fastleeboat]

hi all, i have a 16ft phantom with a mariner 90, with a 10" setback. i used a 141/2x26 tillman prop and we get 62mph on gps. took two years to find that speed, using solid top and bottom mounts is what made the biggest difference, it stopped the motor from moving all over the place
how much mph gain did you get after installing the mounts?

[sharkbite]

I gAined 3mph, I also had to play with engine hights to find the sweet spot. Engine was also offset 11/2 inches to the right for torque purposes.

[2stroking]

can you post a couple pictures of your boat?? id love to see it, and the bottom design, set up, etc-

all of the boats ive had around the length of your boat i have always run V6 merc/mariner outboards on them with GREAT results! im sure you could buy a nice ole 2liter V6 merc and drop that on in place of the 90hp, if you were to sell the 90hp you could cover all the costs of it too. and, if you were to re-ring/refresh it you could easily open up and chamfer the piston ports(notched part of skirts, and the boost port hole on the side), cut the heads for pump premium, and you'd have a little screamer that would pin ya to the seat and gain probably 25mph(or more i think with perfect setup) with proper set up!

i hope what ever you do works out well for you-- im hoping to find another "mid" sized(14ft to 16ft/17ft) performance outboard boat as i have a couple 2liter merc's i want to go fairly wild with-- i am hoping i can find a 16ft laser in the northeast/new england area, and rebuild it lighter and stronger then stock! a hydrostream ventura would be AWESOME as well!

but for outboards, there is just NO comparison to the torque and sheer power of a V6 engine, unless its a really small boat i like the v6 mercs, although the 3cyl omc engines are AWESOME for boats that can handle one(prob what ill put on a gw-invader if the one i want is still around in the next week or 2 when i can make the trip to buy and pick it up!!)..

keep us posted, id like to hear any mods you can or wind up doing to the 3cyl merc, and the results too!! --pat

[fastleeboat]

I'll get some pics soon. The boat is way too small for a V-6!!!..lol

[fastleeboat]

thanks for the info Sharkbite! I had been watching the motor in my rear view while trailering and had noticed lots of movement and this is with the motor down on a transom saver. Good tip...........thanks

[fastleeboat]

218020218019218018218017

[JP Love]

Try a Trophy Plus prop more bow lift than a Laser and hold more on the trim.... you'l never come back to a Laser... Try.. I run Trophy since 1994 and for bass walleye boat is the best ..

[fastleeboat]

I ran a Trophy and it didn't run as well as the Laser on this boat....

[fastleeboat]

Jeff, I have posted some pics of my boat if you want to check it out...........tony

[fastleeboat]

installed some new reeds from Chris Carson Marine and I was amazed at the difference in the acceleration!!! didn't have my GPS with me, so I don't know if top end was improved, but all thru the rpm range it was awesome.....tony

[ChrisCarsonMarine]

Tony,thanks for the report,everyone who has tried the L3/L4 reeds has been quite impressed.I'm convinced that this design from merc is truly " reed valve governed",and our reeds do make a noticeable improvement,Chris

[JP Love]

hi all, i have a 16ft phantom with a mariner 90, with a 10" setback. i used a 141/2x26 tillman prop and we get 62mph on gps. took two years to find that speed, using solid top and bottom mounts is what made the biggest difference, it stopped the motor from moving all over the place62MPH Wow send some pics..

[JP Love]

See mine a Walleye style Model: Legend Viper 165Vhttp://i53.tinypic.com/ocp43.jpg

[JP Love]

http://i51.tinypic.com/n694qv.jpg
With all the gear 55 speedo..
http://i55.tinypic.com/2a96vc6.jpg

[fastleeboat]

http://i51.tinypic.com/n694qv.jpg
With all the gear 55 speedo..
http://i55.tinypic.com/2a96vc6.jpg
try a gps and see the difference.........

[fastleeboat]

I wonder how a Mercury Fury prop would run on my boat? Anybody have any experience with these props? Are they good bow lift props?

[JP Love]

installed some new reeds from Chris Carson Marine and I was amazed at the difference in the acceleration!!! didn't have my GPS with me, so I don't know if top end was improved, but all thru the rpm range it was awesome.....tonyDid you do some work in the intake.. Stock jetting.....

[fastleeboat]

just stock...........

[JP Love]

Tony,thanks for the report,everyone who has tried the L3/L4 reeds has been quite impressed.I'm convinced that this design from merc is truly " reed valve governed",and our reeds do make a noticeable improvement,ChrisStill have in stock for mine 2008 Merc 90 Classic.. I like to replace next spring and do a good timing and maybe put a bit leaner.. Right now the wheater is cold and the engine is strong. Waiting for another prop to do tests this week. My setback and transom wedge give me 3 miles.. Cant wait next saison for the reed.. JP
http://i51.tinypic.com/33f7ul4.jpg

[fastleeboat]

I gAined 3mph, I also had to play with engine hights to find the sweet spot. Engine was also offset 11/2 inches to the right for torque purposes.
where can I get solid mounts for a 2004 merc 90 hp 2 stroke?

[Glastron1987]

It's a LOT of work but 2.5 style sleeves can be made and put in. The scream like a banshee, but the crank and heavy flywheel do not get along very well after awhile.

Both the 90hp and the 2.5's are a 3.5 bore already so what does this mean?

[FMP]

62MPH Wow send some pics..

Tower of power L6 115 Mariner ?