After mixing up two gallons of gasoline and oil using the 50:1 mixture recommended by Johnson, I had trouble starting the engine and keeping it running. There seemed to also be excessive smoking. I added one half gallon of gasoline to the mixture and the engine starts quickly and purrs like a kitten. Am I at risk doing this with the 30 year old engine?
Outboard two cycle mixture.
- Thread starter korchinskyp
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Outboard two cycle
You should mix 5.12 oz of oil not 2.6 as Tim suggested. You mentioned that you mixed the oil with two gallons of gas. 2.6 oz of oil would have been the correct 50:1 ratio if you were only mixing it with one gallon of gas.
You should mix 5.12 oz of oil not 2.6 as Tim suggested. You mentioned that you mixed the oil with two gallons of gas. 2.6 oz of oil would have been the correct 50:1 ratio if you were only mixing it with one gallon of gas.
About 30 years ago, I had an aging Evinrude 6 hp 2-cycle outboard. Instructions for gas/oil mix was 100:1. Engine ran well with no plug fouling or smoking exhaust. A few years later, I bought a replacement Evinrude 8 hp that was essentially the same motor bored out a bit. It had instructions to use 50:1 gas/oil mix. The plugs and cylinders fouled badly. I asked the distributor about this and he told the engine would run well on a 100:1 mix. He further said Evinrude changed instructions to 50:1 for fear people would get the 100:1 mix wrong (go figure....) . I ran that engine on 100:1 mix for years and it ran well. I would suggest you check with the maker (Johnson/Bombardier) and see if that advice is still current.
An easy mathematical formula to remember, as the cans of oil come in 8 or 16 oz, is 8 oz oil to 3 gallons of gas. It's a little more oil than required, but not enough to make a difference. That's what the PO of my 1985 Merc told me he did and what I've done for 8 years, and it still works fine. I also add SeaFoam and Stabil to my fuel (counting SeaFoam and Stabil as part of the "gas" portion of the mix).
if you're worried about mixing it thinner go to a motocross oil, they're higher quality for what a two stroke needs, motul 2t racing oil is what ive used in all two stroke engines ive ever owned and they all come apart sparklingly clean on the rare occasion i have to tear one down that isnt a dirt bike (top end every 10-20hrs).
something to realize is that two stroke oil in a crank case induction engine which is by far the most common we have today has to be capable of precipitating out of an emulsified and then atomized mixture in order to lubricate the engine, heat is what will trigger this and motul has it down pat, the motor gets more oil in the places you need it with less smoking because the oil doesnt hang out and get burnt with the gas like with that quicksilver crap.
something to realize is that two stroke oil in a crank case induction engine which is by far the most common we have today has to be capable of precipitating out of an emulsified and then atomized mixture in order to lubricate the engine, heat is what will trigger this and motul has it down pat, the motor gets more oil in the places you need it with less smoking because the oil doesnt hang out and get burnt with the gas like with that quicksilver crap.
What brand of oil did you use? Some brands create more smoking and stalling issues. I personally like the Tohatsu brand for outboards.
oil should be rated TCW-3 Two stroke, Water Cooled. Because of the much cooler temperatures in an outboard, some of the components of oil designed for high speed air cooled engines may not completely evaporate. Typically this increases the possibility of rings sticking and increases the chances of big chunky carbon deposits, especially around the exhaust port.. http://www.nmma.org/certification/certification/oil/tc-w3.aspx
Oil for high power output air cooled two strokes, like chain saws or racing bikes is different.. Some may work in outboard engines, but the TCW rating states that an oil carrying that rating will be fine in an outboard.
Oil for high power output air cooled two strokes, like chain saws or racing bikes is different.. Some may work in outboard engines, but the TCW rating states that an oil carrying that rating will be fine in an outboard.
bah cloudie the racing bikes have been water cooled now since the early 90's, the oils have been adjusted for that and the bikes run at similar temps to the outboards, only real difference in the engines is the compression ratio and mabey a few degrees of temp if your thermostat is busted and you're running in really cold water, my 15hp honda outboard runs at the same temp that my 125 two stroke did, it just doesnt make 37hp and scream like the devil is chasing you.
also after additional research the standard api tc rating of most other two stroke oils (motocross like i referenced) the main difference from tcw-3 is the api oils are ashless and leave less deposits in the engine, tcw-3 was developed for older carbed two stroke outboards and is inferior in all testing ranges to the api tc rated oils like motul 8002t factory line racing offroad two stroke oil.
also after additional research the standard api tc rating of most other two stroke oils (motocross like i referenced) the main difference from tcw-3 is the api oils are ashless and leave less deposits in the engine, tcw-3 was developed for older carbed two stroke outboards and is inferior in all testing ranges to the api tc rated oils like motul 8002t factory line racing offroad two stroke oil.
Rufus, I'm not very technical, so forgive me if this all has been answered in other of your posts. How easy is it to get motocross 2 stroke oil? For an older outboard like the 1986 Merc 90hp I have on my fishing boat, would there be a big advantage to using motocross oil? Any downside? Always looking for ways to keep my old motor running well. Thanks!
the motocross oil is designed to precipitate out of the atomized and emulsified vapor when it gets heated in the crank case, its like rain from a mist, the oil and gas get vaporized in the carb and enter the engine in the crank case area then the oil just jumps out like raindrops onto the walls and bearings, not claiming to know how they do it but you can find examples on youtube im sure, i know when i switched to the 800 2t motul oil in my dirtbikes i noticed a huge difference when i did the next top end (10hrs) i took the carb and airbox off the case and noticed alot more oil hanging around in there.
that singular characteristic will improve the life of any outboard that uses crank case induction, similarly all of the new port injected two strokes like the evinrude e-tec and the sea doo jetski's are using api tc oil just like the dirtbikes.
you should be able to find the oil you seek at any local motorcycle shop that sells motul products just call around and you should find one with out a ton of trouble, if not you can find dealers online, the oil is more expensive but geez i can tell you it makes a huge difference, no or little smoke and much less odor. its just a higher grade of oil plain and simple.
that singular characteristic will improve the life of any outboard that uses crank case induction, similarly all of the new port injected two strokes like the evinrude e-tec and the sea doo jetski's are using api tc oil just like the dirtbikes.
you should be able to find the oil you seek at any local motorcycle shop that sells motul products just call around and you should find one with out a ton of trouble, if not you can find dealers online, the oil is more expensive but geez i can tell you it makes a huge difference, no or little smoke and much less odor. its just a higher grade of oil plain and simple.
Hey Rufus! you know your stuff! The only thing I would add is to put in a 1/2 ounce of synthetic oil every once in awhile to super slick the cylinder walls. A little acetone added to your gas will make her really go! I am leaving for Cyclelands (Chico CA) 50 year anniversary race night in a couple hours. I flat tracked there for many years. Chief
Thanks for staying on the subject!
All I wanted to know if there was any risk using less oil in the fuel mixture in the outboard.
I did not want to get into motorcycles, etc.
All I wanted to know if there was any risk using less oil in the fuel mixture in the outboard.
I did not want to get into motorcycles, etc.
It's a public forum; the info is worth exactly what you paid for it
. Personally the info about motocross 2-stroke oil is interesting and I might look into it.To answer your initial question... first, it's not completely clear from your description that adding the extra gas was the full solution to the starting problem ... other ideas - the engine was a bit clogged/dirty and the extra gas helped clean it out... or the 2-stroke oil is somehow inferior.
We also have a 30+ year-old 2-stroke (Suzuki 5hp). I religiously use fresh premium ethanol-free gas and Shell Nautilus 2-stroke oil at 50:1, and it runs like a champ year after year. I disassembled the carb last spring, and it was as clean as a whistle, with traces of still-runny 2-stroke oil.
By adding the extra half-gallon, your new mix ratio is 62.5:1, which I don't think is dangerously thin, but I'm not a mechanic. For an expert opinion, you should consult an outboard mechanic in your area.
Thanks kenn: I appreciate your comments as you fully realize that the men who really do know about 2 stroke concepts are M/X dirt bikers/racers and tuners. This expertise can be applied to our outboards. His 62.5 to 1 ratio is probably OK but the biggest concern is what quality of oil is he using? As you realized, that was why Rufus and I were imparting motorcycle 2 stroke knowledge. It can help you to arrive at an intelligent decision on your oil use with regard to quality and ratio of oil.
Another interesting side to this discussion is that my buddy who is a prominent motorcycle tuner says: (Rufus will love this) With todays gas he says to add a few ounces of 2 stroke oil into your tank for enhanced top end 4 stroke lube since the lead is now gone from our fuel! Sounds right to me!
Chief
Another interesting side to this discussion is that my buddy who is a prominent motorcycle tuner says: (Rufus will love this) With todays gas he says to add a few ounces of 2 stroke oil into your tank for enhanced top end 4 stroke lube since the lead is now gone from our fuel! Sounds right to me!
Chief
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I heard something like that too, which is why I am not afraid of using up the leftover mixed gas in the fall by adding it a bit at a time to my truck's gas
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