Need help on a couple 25hp mercs

[flyingscott]

How can u say a Yamaha is a better motor,that is furthest from the truth. That may be your opinion and I respect that but that is just opinion. There is nothing special about the Yamaha that is any different then the merc. It's funny how everyone says the manufacturer knows the engine best,correct, so if that's the case why does nearly everyone run 50:1 in the Yamaha when everyone clearly knows and states on the motor 100:1,but yet no one will do it. I find that humorous. Most,not all,but most won't run the 100:1. I hear it so much ,follow the manufacturer specs but you know as well as I do more than half don't. I agree with most everything you said except yamaha is better, also I don't think mercs are better but I do know our mercs or at least mine will beat a 25hp Yamaha because I've done it several times with my buddy who has the same boat and I actually had more weight in the boat and beat him from one side of my lake to the other. Are yamaha motors awesome, absolutely, but if I got 2 brand new engines,25hp I would go merc all day long because I love the power.

It is no secret that Yamaha is a better motor than mercury. Actually Mercury had them build and design Quite a few of their motors over the years. I am just giving you the info I have I have owned over 20 of them rebuilt 1/2 of them I know what wrecks them.

 

[boater1234]

Okay,then why in the world do u own a mercury, your killing me here,lol. Sell the merc and buy a Yamaha.

 

[ondarvr]

"Need help on a couple 25hp mercs"

Sounds like you have it all figured out, so maybe you don't, good luck.

 

[boater1234]

I don't disagree that yamaha is great but any motor will run forever with proper maintenance. My merc is 24yr old regardless of hrs and runs like new,cherry,pristine. It all comes down to maintaining and caring for any outboard. There is no concrete proof that states your claims,only your opinion. Tons of people will say mercs are better than yamaha but again I would disagree with that to,no motor is better than the other,all the same materials, just comes down specifically to maintaining the outboard and constantly running them without sitting for very long periods of time. Use non ethanol fuel if available and do lower unit oil changes, impeller and flush the engine and it will last forever. For the money Tohatsu hands down is the best for the price,Tohatsu is the biggest outboard manufacturer in the world and they build stellar outboards for them,nissan,evinrude, and mercury. They are awesome outboards. Yamaha is so overpriced like Honda it's crazy. I can,get a brand new 20hp 4 stroke Suzuki efi that is so far ahead in technology over the yamaha for $2500,the carbed yamaha 20hp 4 stroke is over $3k,that is so overpriced. The suzuki is a much better and newer technology,not a close call,also so many people tell me the small yamaha 4strokes are dogs,I know the suzuki or the merc 20hp 4 stroke is not.

 

[boater1234]

I also know a 25hp 4 stroke yamaha is like 180lbs,that's insane,a 25hp 4 stroke Suzuki will run circles around it and it's cheaper to with a longer warranty, that is my next outboard, either a 20 or 25hp 4 stroke Suzuki hands down.

 

[boater1234]

All I know is your saying mercs are not in the same league as yamaha but you own a merc,no direspect but talk about contradicting yourself. Thanks,I have very good luck with mercs or yamaha for the right price.

 

[flyingscott]

I own Yamahas and Mercs, Evuinrudes.Johnsons,McCullochs,Scott Atwaters,and Firestones. So I will keep my own opinion on these motors as I have first hand knowledge of all of them and have worked on all of them. I wonder why you are so bent out of shape because I think Yamahas are better motors since I am not a fanboy that has to have one color. You obviously think Suzukis are better motors yet you are running a Merc. You wanted opinions you got them then you didn't like them makes me wonder why you posted here in the first place as you have all the answers anyway.

 

[boater1234]

I don't think the suzukis are better as in quality, I just like the idea of newer technology, you know what I mean. I think just any outboard can be bulletproof with the proper maintenance, that is all I'm saying. With the suzuki, I love the idea of no mixing oil which is the big one for me,the engine is so much quieter,smoother,gas savings is huge,plus it's a 3 cylinder so it would have near the same power,maybe even more who knows,the suzuki is a whole diffferent breed of outboards,plus having a huge 6yr warranty is just another huge perk. If I could find one of these mercs or equal 25hp 2 strokes absolutely brand new out of a box then no question I would have a merc, yamaha, johnson,whatever 2 stroke it is hands down over a new 4 stroke Suzuki. I love the power to weight ratio on these 2 strokes,very simple design, super simple to maintain and reliability is second to none. If I had a chance to do it all over again, honestly like 3yrs ago one of my local marinas sold the 25hp 2 stroke sea pro mercury which is a brand new Tohatsu built outboard with merc decals. I didn't have the money at the time but a powerful commercial 440 cc engine out of the box for only $2700 was an insane price and if I had the money I would of bought 100 of them and resold them forv $3500 a pop all day long,but unfortunately that's not the case and I missed out on the best deal possible and I kick myself everyday.

 

[boater1234]

Now the only 2 strokes out here is an etc and they are awesome but holy overpriced to say in the least. Way to much money. Over $4000 for a manual start 25hp etec,for that price I can get a 25hp suzuki with power T and T with electric start for less and for a base model 25hp suzuki which is what I want,manual start short shaft I can get a brand new out of the box for $3100ish

 

[boater1234]

((((((((((FLYINGSCOTT,i was wondering when you did the manifold gasket change did you do both of them,the outside and inside gasket?Also do i need any extra sealant for the gaskets or is the gasket itself enough?I have replaced near everything but this gasket and as you said with the little hrs on it i don't have to be to concerned yet as i will do it in the fall.))))))))))In the fall i'm putting a nice fresh coat of paint on my 93 which i plan to keep and getting the 25hp carb,why not,right.I can always use the extra power if i ever need it one day but it has a ton of power now already for a 20hp.I have just been doing some serious extensive reading and it seems that mercury made a huge mistake by going away from the Nikasil powerheads and going to the Mercosil powerheads because the Nikasil powerhead was tried and true and as bulletproof as they come for over 20yrs and near problem free as with this new mercosil powerhead being introduced in the early 90s was just the opposite.So i am going with my 93 with 120lbs of compression on both cylinders,can't get much better than that.I am also going to run a water/fuel separator on this engine so i know that the engine will run 100% free of water.I run only non ethanol fuel anyways.If i had a new 4 stroke i may run ethanol fuel because i use it up fast but i know on these pre mix outboards using non ethanol fuel is so vital the the life of my outboard.With a 4 stroke at least if water is in the gas the most that happens is it won't start till you take care of the water issue but you won't suck any water into the internals of the engine like a premix engine that has it mixed right in it.That is another reason i may go with the suzuki in time.I know though that if i run that fuel/water separator i will be ok for sure.Thanks for all your help.Just because i don't agree with all you said and vice versa does not mean i don't value your opinion and help,ty.

 

[boater1234]

Flyingscott?????????

 

[boater1234]

No help,ok,thanks anyways.

 

[flyingscott]

No help,ok,thanks anyways.

You have to change both gaskets on the exhaust covers not just one. I run 10% ethanol in mine all the time with no problems.

 

[boater1234]

Thanks

 

[boater1234]

Is there a difference between the nikasil and mercosil powerheads? Most everything I have read points towards the mercosil powerhead having the most trouble and the nikasil powerheads being bulletproof, almost never any issues. There are people who have like u said scrap piles of these merc 25s but almost all are the mercosil powerhead. I have 2 beautiful engines, one is my 93 20hp which I believe has near the same if not the same power as my 02 25hp merc. I don't know what it is but I have read that the early 80s to early 90s 20/25hp mercs were so much more powerful and faster then the mid 90s up to when production stopped. There is so many people who swear that the yrs I mentioned were just faster and more powerful than any other yrs made. Is there any truth to this,any actual facts to back what they say up? I have even heard from so called merc mechanics who have worked for merc for many yrs chime in on it saying those yr mercs were pumping near 33hp out at the prop. All I know is that plenty of people claim what I've personally seen out of my 93 20hp,they seem to have rediculous wot speed and mega power to weight ratio. Now I have a 02 that is a gem mint 10 but so is my 93,it's a gem mint 10 but I'm having such a hard time deciding on which one to keep because they are both cherry. I like the tiller on the 93 because no washers can just fall out like the plastic one on the 02 tiller,I love the cowling design of the 93. The 93 has 25hrs and the 02 has 4hrs. I don't know which to keep,they are so damn nice. In time I'm going to sell both and get either a 20 or 25hp suzuki so that is my plan. For now though I am keeping just one merc,I never had to pick between 2 gem 10 engines. I am torn but am drawn more to my 93,there is just something about that 93,I love it but I love the way the 02 runs also. Hard choice here. Are there any advantages or disadvantages you can tell me about on either of them that may steer me one way or the other, any help on this would be appreciated. I guess my biggest this is hearing so many of the mercosil powerheads blow that it scares me a bit, that is my biggest hang up. Thanks for any help.

 

[flyingscott]

Mercosil block
Mercosil is what the block is made out of.
Extremely hard does not require plating of the bores.
Can be bored out.
Waterpump must be changed religiously.
Should be run 50-1 NOT 100-1.
Mercury and wiseco pistons can be used.
Can be bored out to .040

Nikasil which is a trade name, will be referred to here as chrome plated.
Bock is aluminum.
Bores are chrome plated.
Must be re-sleeved or re-chromed for a rebuild cannot be bored.
Waterpump must be changed religiously.
Run 50-1 not 100-1.
Mercury pistons and rings must be used for re-chroming.
Wiseco pistons must be used on a re-sleeve.

Most failures I have seen on these blocks is when the water pump fails.
Or people run 100-1 and the crank bearings go out but that is not as common usually just scores the piston.
I have seen failures on both motors not one more than the other.
But the Mercosil block will usually have more damage from an overheat.

 

[boater1234]

well i do change the impeller at the very least once every 2 yrs.The impeller from the 02 is original and some how it's 100% perfect.Not even close to looking used and the engine works awesome.My 93 i changed it because it needed it just a few months ago.As for the 100;1,we both think very different as there are 100%facts that proves that an engine that runs all the time and ((((doesn't sit for long,long periods of time)))))can run on 100:1 with no issues,all that said though i do agree as cheap oil is you may as well run richer then that for better protection.I believe 50:1 is overkill and we have been programmed to run that.I am running at 60-70:1 and it still smokes plenty as with a 100:1 it barely smokes at all.I will run mine between a 60-70:1 oil ratio which is just a hair leaner then 50:1 and i know won't hurt it because tons of people are running more like 75-80:1 with no ill results and actually report a smoother running outboard.I found a guy who actually ran a test on 50:1,75:1 and 100:1 and he found the 75;1 to be the best results as the cleanest engine internally with no ill effects or damage,he also went on to say the 100;1 had similar results but like you said and i agree the 100:1 can be catastrophic and oil is cheap as stated earlier but also has proven can be run as long as there is no long periods of it setting.I also use full synthetic oil which i know lubricates better than dino oil. i personally have never seen a failed engine from a slightly leaner mixture in all the yrs i have owned or ran outboards or actually heard of any but i have seen over heating do major damage.


Thanks for the info on the powewrheads,it seems like as advertised the nikasil powerhead is less sensitive to heat or less damage can occur compared to the mercosil powerhead but to change the impeller when it should be changed,according to my manual it says every 2 to 3yrs depending on use.Every 2 yrs should be plenty imo unless you constantly run into sand which can damage the impeller bad.

 

[boater1234]

So if you had the pick between a gem mint 02 or a super gem mint 93 which one would you really go with?I know most people say the newer one but that aside just your opinion?I personally think the 93 has so much more power,is there anything to those yrs compared to the newer ones?

 

[Chinewalker]

100:1 simply doesn't leave enough of a film on the steel parts to prevent corrosion when the motor isn't in use. OMC learned that the hard way in the early 1990s and that's why they stepped back from the 100:1 recommendation, back to 50:1.

 

[flyingscott]

So if you had the pick between a gem mint 02 or a super gem mint 93 which one would you really go with?I know most people say the newer one but that aside just your opinion?I personally think the 93 has so much more power,is there anything to those yrs compared to the newer ones?

Pick one and live with it I am not going to answer the question, because every time I tell you something you answer back why your way is better. You have the info pick one