Under rated?

[will941s]

Since I have a abundance of free time in the off season of fishing, I like to research my OB's and find out where they came from, and technical info. Ive owned alot of OB's but the two I have kept and still run are two Merc 25's. One is a 89' short shaft and the other is a 98' long shaft. Both 2 strokes, the 89' is bare bones tiller, and the 98' is fully decked out remote. Both run like scalded dogs and kill johnnyrudes and Yamahas of comparable size....will pass a 35hp e-rude or keep up with it...according to the size of boat it's on. 40's will pass them everytime though. The only difference in the two is the newer one has the Mercosil bores...I think thats about it. Anyway, I talked to Merc factory guy about a week ago, and talked about the motors. He said they were one of the hottest selling they had while they were in production, and were very high performance in the market they were sold in. He also said something interesting......says that Merc under rated the motors. They should be more comparable to a 30hp. Is this true? If so it would probably explain the performance I have had with them, and not just me but most people I know who have them. I would like to hear some feedback on this or some experiences. Thanks.

 

[Whoopbass]

Re: Under rated?

I've heard the same thing at least for the older mercs. I run JohnnyRudes and I noticed my older non thru exhaust 25 hp outboard is a couple mph faster then my newer thru hub exhaust outboard.

 

[will941s]

Re: Under rated?

Thanks, at least now people won't think im bias, or crazy. I've had a 25 and 35hp Evinrude also, they were good motors. Alot of low end power but the top speed always seemed to fall off once it hit WOT, but it get there like a bat outta *^$@. The Merc 25's take off pretty quick but the top speed is only limited by the boat it's on. The lighter you are the more it'll scream. My 14.5' BayRayder Side Console will top out at about 35mph with me (220 pounds), a cooler, tackle box, 4 rods, a trolling motor and 2 batteries. Not to mention my onboard tool box. I have the tool box and one battery under the front casting deck to even out weight. The other one is on a 14' Duracraft Jon, not sure what the top speed is on that one, but taking curves on the river is like road course racing in nascar. It'll slide if you don't watch it, but FLIES.

 

[JimS123]

Re: Under rated?

Evinrudes were always noted for quiet, durability and longevity. Mercs were always noted for being troublesome and finninky, but the Merc officianados didn't care becausetheywere faster than all others.

So, if you wanted to go fishing and have fun, you bought a Rude. If you wanted to impress your girlfriend and race everybody, you bought a Merc.

In later years it was learned that Merc cheated to get their reputation.

 

[Whoopbass]

Re: Under rated?

Mercs might be faster then JohnnyRudes but their not going to "fly" by them. I was fishing the other day and there was a guy with an aluminum boat with a early 90's merc on it. The motor was stripped of its decals but the guy said it was a 30hp. He claimed he put a 4-stroke carburetor on it and now his boat will do 36 mph and sucks half the gas then before.
The guy I bought my current 25hp Evinrude from claimed that this motor pushed his boat to 38 mph on the gps. I only paid $150 for it because it needed a new lower unit. I put a lower unit on it that I had then tested it out on my boat and could only get 26 mph on the gps.
My point is most of these super fast motors that blow away every comparable outboard away are nothing but stories.

 

[saumon]

Re: Under rated?

... the guy said it was a 30hp. He claimed he put a 4-stroke carburetor on it and now his boat will do 36 mph and sucks half the gas then before...

Amazing! I don't know it was so simple...I'll now put 4-stroke carbs on all my 2-strokes and save big on gas!

 

[Frank Acampora]

Re: Under rated?

I'll tell you a little story about Mercs: A while back I did some repairs on a four cylinder, 100 horsepower, two stroke Merc. Basically, I cleaned the four carbs (hint of more horses) which were gummed up completely, replaced the accelerator pump, replaced the plugs, and reset the timing.

On a 21 foot round bottom cuddy with three people, that Merc ran at 39-40 MPH top speed while on a 21 foot deep vee cuddy, my 140 engine ran 38 top speed.

Do you really think that merc was delivering only 100 horsepower to the prop? I doubt it. More like 120-130.

Mercury has long been known to deliver more than rated horsepower AND back in the day when outboards were theoretically calculated at the crankshaft, Mercury was using dynomometers at the prop shaft.

 

[will941s]

Re: Under rated?

Good deal. The Merc 25 is a fast little motor, and from the time I have had both of them, they have been VERY reliable. The 89' has outlasted a Erude 25 and a 35hp, and a Tohatsu 25hp (well Tohatsu blew a head gasket). The e-rudes went to the wayside. I am crazy about maint. though. I clean the carb on both of them every two years, impellars and t-stats every year, plugs twice a year, lower unit oil every year....and both run fuel/water separators which I change the filters every year. Not to mention I do compression checks on regular basis because if a problem is forming...I want to know about it. To my best knowledge these are great motors, and bulletproof. As with anything else, if you take care of it, it will run for a long time and be trouble free. As far as problems I have had, here is the list. Had a bolt break off on the 98' then changing a t-stat once (easy out, new bolt $7), primer on the 98' cracked once (fixed with carb rebuild $35), Lower unit went on the 98' from hitting a oyster shoal at WOT ($250 used, pressure test for free), broke the midsection on the 89' by hitting a oyster shoal and rock ($75 got a whole entire parts motor). Thats it.....all the major ones are not from Merc being bad motors, just when your running in 14' of water you don't expect a shoal. BTW, all speeds were checked with a GPS unit.

 

[Whoopbass]

Re: Under rated?

They guy I mentioned with the 30HP Merc with the 4-stroke carb that would do 36 mph (lol) well it just so happened him and I ran back to the ramp at the same time. I have a 15 v-hull with a 25 hp Evinrude that is pretty loaded down and the other guy has a 12' narrow turd. I about ran over the the top of him going back to the ramp. The guy is so full of crap about everything i'm guessing his Merc is more like 20 hp. It's bigger then a 15 but looks to small to be a 30 (all the decals have been removed).
There is another guy with a 25hp merc and a 14'-15' flat bottom that I will have to race when I get the chance. His rig is pretty fast but he's not going to blow me away. He might slowly pull away if he's lucky.
One thing I can say about those Merc's is that they idle better then my Rude and they seem to be quieter.

 

[will941s]

Re: Under rated?

LOL.....if you ever make to Charleston, South Carolina hit me up. We can race then catch some nice bass, blues and maybe some spot. I did'nt know you could put a 4-stroke carb on a 2-stroke. The 18-20-25 have the exact same coweling. 9.9-15 have the same smaller version of the coweling. A 30hp has a coweling that looks like the 40-60hp coweling with the vents in the back. Who knows what that guy is running. Mine are stock, no mods at all....I like the reliability too much to compromise that. If I want more power or speed I will step up to a 40hp, not attempt to change something and risk killing one of my motors. OB's are expensive! As far as idle, I've never another brand idle as rough as a merc 25. Even brand new out of the box they shake at idle.

 

[dingbat]

Re: Under rated?

By law, a outboard has to be within plus or minus 10% of the advertised HP.

The only way to compare motors is on a dynamometer.

 

[Chinewalker]

Re: Under rated?

Mercury hasn't underrated their outboards since the 1950s - some myths never die out. Back then, they rated their motors at 4000 RPM, and would ship them with a prop that allowed it to spin up over 5000. Their lit would have an asterisk after the horsepower ratings - "*Horsepower varies with RPM." Any claims of "my 20 is faster than his 30" and likely due to other factors, including, but not limited to set-up, prop selection, hull differences, hull condition, weight distribution, motor condition, prop condition, etc. Bottom line - if you have a Merc 20 and an Evinrude 20 on the same hull, propped for similar workload, they'll perform about the same. Some differences show up when comparing 2-strokes and 4-strokes, DFI vs. carbed, etc. but in the end, one isn't going to blow the doors off the other. As Dingbat noted, they are governed by industry standards that set limits on how far off the rated horsepower you can be...

 

[boater1234]

Re: Under rated?

I know you guys may laugh but i have a little 15hp 2stroke merc on a 14ft ncs alumacraft,that motor will flat out get it,i don't know exactly how fast but when i tested it out i had tears running down my face from the wind burn.If i had to guess i would say 25 to 30mph,just a guess.I def know i'm going well over 20mph.I have seen tons of videos on you tube with the merc 25's and 15's and they are power houses.There is a brand new 25hp merc 2stroke for sale never been run,last yr of production motor,i want to say it was a 05 or 06.The marina wants $2300 for it,thats a steal if you ask me.

 

[will941s]

Re: Under rated?

I love these motors. Never ran the 15hp but I heard they will get up and go, my dad used to have a 94' 9.9hp that would plane his 15' Monarch. That was unheard of, it was a thick heavy boat. I'm happy with what I have.

 

[pecheux]

Re: Under rated?

Evinrudes were always noted for quiet, durability and longevity. Mercs were always noted for being troublesome and finninky, but the Merc officianados didn't care becausetheywere faster than all others.

So, if you wanted to go fishing and have fun, you bought a Rude. If you wanted to impress your girlfriend and race everybody, you bought a Merc.

In later years it was learned that Merc cheated to get their reputation.

That was Mercury's reputation and the way it seemed to be back in the late 50's ... but then was it under rating or better performance OB's ??? Donno but declared hp for hp Merc OB's were obviously faster than other brands.