mercury 2 stroke outboard oil mixture question

[scoobeb]

You did a fantastic job on that engine!

Thank you,means a lot to me.I busted my hump cleaning it i mean for many man hrs.I took off the 20hp plate under the lower cowl and to my surprise there was what's called mud daubers we call them here in fl.They take mud and build nests with it,they look like wasps but are harmless.There was quite a bit caked up under the plate but it wasn't harming anything thank God.When i say i cleaned it i mean i cleaned every milk and cranny,crevice i could reach to clean,every hole,everything i could get to.I cleaned i can't tell you how much old grease off this thing,wow.I used dawn soap to clean the whole outboard.I used a whole huge bottle in a spray bottle.It was worth every minute.

As far as the all in one shifter,i love it and think that is what makes the mercs special. that is the best feature to me.I have never once had any issues.This engine shifts like butter,i mean really silky smooth,no grinding or any force needed like the new 20hp 4stroke merc i had,that takes some force to shift, but it wasn't broke in one bit yet to be fair.


As far as the fuel air mixture it was around 1 1/2 turns out from seated and i notched it back i mean a tiny hair towards the rich side to be safe and it runs like a sewing machine.It is a 50:1 engine and that is what i'm going to run because since i'm using full synthetic on it i'm hoping it will run cleaner but i won't skimp out on the oil especially after all the work i did to it.I also use lucus stabilizer in my non ethanol gas and ring free.When i started taking off the original stuff it all like just crumbled to pieces,especially the coils,they just fell apart.All the wires were corroded and need to be replaced,Plus they were the wrong length wires and wrong coils so i made sure everything on this is as perfect as it can get.I'm very anal when it comes to maintenance and making sure everything is up to par.I believe in doing it right the first time.

 

[scoobeb]

Thank you guys for all the kind comments,means a lot to me as i told pappy.I think i will keep this outboard for a long time maybe even permanently.The way i take care of my engines it will look like this even another 15-20yrs down the road.One of the greatest things i have learned about this engine from the older guy i bought it from was the prop is actually the original which is amazing to me.The prop is 24yrs old,wow.

 

[scoobeb]

Jlbjeff,your merc runs 50:1 doesn't it? You run at 80:1 with it though and have never had any issues? I've always wondered why only Yamaha pushes 100:1 but every other brand outboard runs 50:1. I believe any 2 stroke can run at least 75:1 to run a hair cleaner but I will still run 50:1 no matter what. I may run it a hair leaner but not to much.

 

[JL8Jeff]

Jlbjeff,your merc runs 50:1 doesn't it? You run at 80:1 with it though and have never had any issues? I've always wondered why only Yamaha pushes 100:1 but every other brand outboard runs 50:1. I believe any 2 stroke can run at least 75:1 to run a hair cleaner but I will still run 50:1 no matter what. I may run it a hair leaner but not to much.

My oil injection pump was bad when I got the motor (1994 60/45 jet) so I've been premixing. I ran 80:1 to 100:1 in my old 1999 Johnson 40 as well. Remember, the 50:1 mix is the ratio needed for WOT. The oil injection or VRO mixes closer to 100:1 at lower speeds. I don't blast around at WOT and I usually only run for 10-15 minutes at a time so I don't have an issue with the 80:1 mix. If you're going to need to run close to WOT for any amount of time then the 50:1 is a much safer mix. It really depends on the overall combination of the conditions, location, boat/passenger weight, running time.

 

[Pappy]

As far as an engine running lean on a heavy oil ratio? Pure bunk.
If manufacturers recommend doubling the oil for any racing situation on a bone stock carbureted engine then that engine is run at WOT for whatever period necessary for the event.
At WOT the engine has to get rid of a massive amount of heat. Do you think a manufacturer would recommend this if they even thought that a richer oil mix would lean out the engine? That is a boat ramp myth.
All manufacturers that used carburetors set the high speed jets on the rich side of optimum just for safety sake and a reduction of warranty claims.
Want to know what is currently leaning your engine anyway? Ethanol fuel.
10% ethanol mix in gasoline leans the average mixture 6%. Do the math! Has not made a dent in failures.
In short.........oil is cheap and powerheads are not. Additional oil can and will protect your engine better should you get debris in your carbs or an overheat.

 

[JL8Jeff]

I think he was referring to running lean as in a lean oil/gas ratio, not a lean fuel/air ratio (at least that's how I was reading it). With a smaller motor, I would think there is more of a need to run a higher rpm so the stock oil mixture is a safer way to run.

 

[Sinkingfast]

I think Turbo was referring to the massive #-o increase in viscosity by the added oil, causing a lean on fuel condition. If the motor is affected by running say 32-1 over 50-1, that motor was lean to start with.

Just run 4 0unces per gallon of dino 2stroke oil. Better chance of having it 20 years from now.

 

[Pappy]

Again, not correct on either count.
When we jet for racing we lean the hell out of the engines in the fuel department. We then double the oil. The reasoning for this is that the oil will help cool the pistons and also provide a ton more protection against sticking a piston due to the lean condition and fluctuations in cooling water volume and pressure. Production engines both small and large are pig rich compared to what you can run.
In a production situation the main reason for running additional oil is to protect the engine when things go South. Overheats and dirty carb circuits being the two main culprits. A production ratio of 100:1 doesn't have a prayer of protecting an engine running hard and catching an ice bag over the water inlets. The pistons are running at their hottest (most expanded) and the block is or was running at its coldest. The piston grows beyond its designed in tolerances immediately and it's metal to metal on the exhaust side of the piston to the cylinder wall. The only thing that has a prayer of helping is lubrication. If you are not quick in identifying the issue then the piston gets pushed over to the intake side and locks up. Once it locks there is a good chance it will put a rod through the side of the block.
Like I said in an earlier post, oil is cheap and powerheads are not. I make an easy choice and run additional oil.

 

[scoobeb]

Well i got one thing going for me,i don't use ethanol fuel, i use nothing but ethanol free fuel in my boat engines.

 

[Pappy]

Same here Scoobeb! One less hassle.

 

[JMichael]

Well i got one thing going for me,i don't use ethanol fuel, i use nothing but ethanol free fuel in my boat engines.

I try to but this year it's going to have added challenges to do so. Up until a few months ago, I had 2 sources for eth free fuel within 25 miles. One sold out to another company and the new owner is not going to supply the fuel any longer and the other just closed their doors and went out of business.

 

[scoobeb]

If you use your outboard allot you will have minimal issues if any,let it sit with ethanol fuel,forget it. I use ring free and Lucas stabilizer,the green bottle in Walmart for all my gas and never once had any issues even sitting for months. Good stuff. I also do a de carb once every 6 months on my outboard, 3/4 gallon of gas,1 can of seafoam,works awesome.

 

[scoobeb]

I didn't want to start a whole new thread but what would be symptoms of bad timing on my merc. I have been reading allot and it says don't ever mess with the timing if the engine runs good,but I want to learn what I would be looking or hearing for if the timing was off. Thanks for any help.

 

[Pappy]

Short version......If the timing were low you would not reach your normal RPM. If it were high you may be replacing a piston depending on how high and other factors.

 

[WaterWaif]

I just wanted to update my engine,I replaced everything except the power head and lower unit gears basically. I did new,coils,wires from coils to plugs,new plugs,I replaced even the bolts holding the coils in as well as the shell that goes over the coils. I replaced lower unit oil and gaskets and drain plugs,replaced all the gas lines and new line from thermostat to the pee hole,new thermostat and gasket by the way was my issue of it not warming up,someone just stuck the shell of the Stat in with the gasket but completely removed the whole Stat so it was never warming up and always running cold. I replaced a complete new fuel filter assembly as in hoses and all,replaced the male gas intake on the engine as well,replaced a complete water pump kit,everything, impeller, gaskets,washers, key,housing,intake tube,It's all brand new,rebuilt the entire carb,new gaskets, needle,everything but the float which was good. Set the fuel air mixture screw to factory specs. New pull cord .

I de greased the entire engine I mean spotless, what fun that was,then I re greased all the fittings and anything that moves,lol. New 6 gallon tank and line, 7 bottles of full synthetic tcw 3 oil,greased the prop and spline. I think that covers most of it,runs like a sewing machine now.This will be in my possession until i either die or decide it just eats to much gas and i'm ready to go to a 4stroke. I just can't see myself getting rid of it,it is by far one of the cleanest 20/25hp 2stroke outboards on the planet unless you pull one right out of the box,compression is 100% perfect also.I had a close friend offer me a large amount of money for it and turned it down without hesitation so that will tell you what i think of this outboard.It sat for a very long time so to me it was worth putting a hair over $200 into when now i know everything as far as maintenance is taken care of for yrs now except like the lower unit oil change every 6 months or so.All i can do is hope it lasts for a very long time which i believe it will.

Here are pics of it all done and greased up. The only other plan I have for it is to sand everything above the decals and fill in any gashes with epoxy paste and then repaint it nice. The rest of the engine looks new,let me know what u think for a near 24yr old engine,imo,i think it can't get much nicer then this and i have let alot of really nice engines slip through my fingers and have extremely regretted it to the core of my soul,this time i won't make that same mistake.This motor in amazement has the power of a 25hp even know it's a 20,i cannot believe how much power this little motor has.I am going to the lake next week and this time i'm grabbing my gps because i forgot it last time and i will post how it does on a brand new 1648 flat botton jon boat with me and with 2 in it,thanks.

Reads great!Nice.

We should take wild guesses on GPS results?
I'd guess upper twenties on calm seas and medium weight/ build rider.
Mid twenties for two.
O.K. ...25 avg. :---)

 

[scoobeb]

Short version......If the timing were low you would not reach your normal RPM. If it were high you may be replacing a piston depending on how high and other factors.

Well I'm going to GPS my wot speed soon. I know from experience with these outboards as far as speed with just me on a 1648 jon boat I should hit between 26-29mph. If I'm in the teens or very low 20s like 20-23mph I know something is not right but from the feel of it she hauls a$$. I have watched over 300 videos on YouTube on this outboard and no one was below 26mph even with a full load. I do know these mercury's have so much power,I've had great luck with them,the compression on both is dead even at 125lbs so that is good. I will post GPS results In the next few days.

 

[scoobeb]

I will soon gps my speed and post

 

[scoobeb]

I may need to raise the motor a hair for optimal speed.

 

[scoobeb]

As I thought, the motor is a complete powerhouse. Wot with near 1000lbs total weight I hit 28.3mph which is insanely impressive for just a 20hp. This by far one of the most powerful Engines I have ever used. I smoked my buddy's 20hp 4stroke Tohatsu in the long run,off the line he got me because he was using a 10 pitch prop and mine was 3 sizes bigger at 13,we both were running identical boats,1648 alumacraft flat bottoms so it was a fair run. He had much less weight of around 700lbs total weight, he got us off the line but I caught him and passed him in a matter of seconds. I was seriously highly impressed with the power and torque of his 20hp 4stroke Tohatsu, it just amazed me. They are getting these 4strokes better and better every yr as far as trying to get near the power of a 2 stroke. After seeing how his Tohatsu performed I wouldn't hesitate one second to run one on my Jon boat.

 

[turbotodd]

All (well a lot of them) of the old <40hp Yamaha outboards were 100:1, they were designed to run 100:1. Of the thousands that we sold when I worked there, nary a single powerhead failure. Lots of water pumps, and questionable pumps that owners would say "well it works" (but it was just a real weak pee stream), and they never died, though, in a few weeks those guys were usually back needing impellers, cups, etc. I take that back, I think I put 2 powerheads on 25hp twin carb motors, because the owners had hit submerged objects HARD and repeatedly (flooded timber) which twisted the crank and took out the labyrinth seal. Yamaha picked up the tab on one, the other insurance claim. I remember both quite well.

Take a 100:1 motor (specifically the 25hp twin carb) and run it at 50:1 and I can tell a huge difference in run quality. Top speed, no difference. Idle and mid range, night and day. Most owners won't notice it. Usually had to richen up the idle mixture on those motors whose owners were hard headed to the point where they were going to run 50:1 no matter what was recommended. About a 1/2 turn on the screws, then up the igntion lead from 7ATDC to 3-4 ATDC, and they'd purr like a kitten. Leave them alone and they'd sneeze fiercely until they were hot (not warm, hot). This was common on all of them, even brand new ones running 50:1 break-in mixture-as recommended by Yamaha. These were not racing engines, racing engines could care less about idle quality, oil usage, fuel usage, smoke, or anything else but making the most power and speed. Exactly like a lot of duck hunters in this area, they could care less about idling...all they want is to have the fastest "25 hp" motor regardless of whether it'll go into gear without crunching or if it'll even idle below 1500 RPM at all. wide open down the narrowest canals, 2-3-4-5 boats wide beating and banging each other at 50+ mph. I did it a couple times and I was not impressed. It's not fun.