Why is my Engine a Heavily Smoker ?

[Locozodiac]

Just a comment of what cracy people using outboards can do to them. One day my gardener who often sees me water my boats/engines on the parking lot after use, made me this comment, he used in the jungle area where he worked on a river, a Evinrude 55 HP, 2 strokes engine that smoked heavily, worst than a Oriental. Asked him what was his gas/oil ratio. Don't know was his answer, we use a complete filled tuna round can for every gallon of gasoline we put into the tank.

Was puzzeled by his tech answer, happens to have at hand a well made round container made by Sea Choice Marine Products that has different gas/oil ratios, so filled a complete tuna can and poured it into the container. Guess what, the guy had been running for years on 50:1 ratio instead of 25:1. Plugs didin't last long and the boat looked like an old carbon train smoking up river.

Now he knows for sure the exact gas/oil ratio. Wanted to comment that a complete filled standard tuna can, can mix perfect ratio 2 gallons(3.78/gallon each) of gasoline.

Happy Boating

[captnjack]

You must have very small cans of tuna.

Around here, tuna comes in 6 ounce cans. 1 gallon = 128 ounces. 128/6 = 21.3:1

Darker smoke (not steam) usually = excess oil, so this makes sense.

[codprawn]

Originally Posted by Locozodiac

Just a comment of what cracy people using outboards can do to them. One day my gardener who often sees me water my boats/engines on the parking lot after use, made me this comment, he used in the jungle area where he worked on a river, a Evinrude 55 HP, 2 strokes engine that smoked heavily, worst than a Oriental. Asked him what was his gas/oil ratio. Don't know was his answer, we use a complete filled tuna round can for every gallon of gasoline we put into the tank.

Was puzzeled by his tech answer, happens to have at hand a well made round container made by Sea Choice Marine Products that has different gas/oil ratios, so filled a complete tuna can and poured it into the container. Guess what, the guy had been running for years on 50:1 ratio instead of 25:1. Plugs didin't last long and the boat looked like an old carbon train smoking up river.

Now he knows for sure the exact gas/oil ratio. Wanted to comment that a complete filled standard tuna can, can mix perfect ratio 2 gallons(3.78/gallon each) of gasoline.

Happy Boating

Don't you mean the other way around???

[ribpilot]

Originally Posted by codprawn

Don't you mean the other way around???

You beat me to it

[jyasaki]

Originally Posted by captnjack

You must have very small cans of tuna.

Around here, tuna comes in 6 ounce cans.

Yeah, but that's 6 oz by weight, not volume.


jky

[captnjack]

Originally Posted by jyasaki

Yeah, but that's 6 oz by weight, not volume.


jky

True but I don't have an actual can handy. 6oz volume of water = roughly 6.1oz weight. Assuming tuna is little denser than water the mix gets closer to 25:1. It can't get anywhere near 50:1

[Locozodiac]

Originally Posted by captnjack

True but I don't have an actual can handy. 6oz volume of water = roughly 6.1oz weight. Assuming tuna is little denser than water the mix gets closer to 25:1. It can't get anywhere near 50:1

Resuming: If you pour 1 complete tuna can of oil per gallon (3.78 lt) , will give you a 50:1 mix ; 1 can will mix adequate 2 gallons to 25:1. The can is 85 mm diameter/40 mm height/175 gram. Maybe a good mix gas/oil ratio to new boaters without experience on mixing ratios. 1 full tuna can per each 2 gallons, 3 full tuna can for a complete 6 gal gas tank. But eat firts whatever was in the can....

Happy Boating

[Poly]

Originally Posted by Locozodiac

Resuming: If you pour 1 complete tuna can of oil per gallon (3.78 lt) , will give you a 50:1 mix ; 1 can will mix adequate 2 gallons to 25:1.

you've still got it the wrong way round

[Locozodiac]

Originally Posted by Polwart

you've still got it the wrong way round

You can be flexible, the engine will work just fine. In math the order of factors doesn't alter the product, seems we have a different math point of view.

[Poly]

Originally Posted by Locozodiac

You can be flexible, the engine will work just fine. In math the order of factors doesn't alter the product, seems we have a different math point of view.

1 tuna can of oil in 1 US Gal will give approximately 25:1 fuel:oil ratio.
1 tuna can of oil in 2 US Gals gives approximately 50:1 fuel:oil ratio.

which is the opposite from what you stated twice now.

[captnjack]

Originally Posted by Polwart

1 tuna can of oil in 1 US Gal will give approximately 25:1 fuel:oil ratio.
1 tuna can of oil in 2 US Gals gives approximately 50:1 fuel:oil ratio.

which is the opposite from what you stated twice now.

Yes, about that.

And running a 50:1 engine at 25:1 will produce lots of smoke and fouled spark plugs too. Running a 25:1 engine at 50:1 will not make smoke but it will probably shorten its life. By how much? Who knows.

[Locozodiac]

Originally Posted by Polwart

1 tuna can of oil in 1 US Gal will give approximately 25:1 fuel:oil ratio.
1 tuna can of oil in 2 US Gals gives approximately 50:1 fuel:oil ratio.

which is the opposite from what you stated twice now.

Pol, why didn't you correct it in your first post ? "you've still got it the wrong way round" Would have been better with less space lost in double posts. Don't you think, and please don't give a back answer to this one.

Happy Boating

[Locozodiac]

Or should have been like this:

And running a 50:1 engine at 25:1 will produce lots of smoke and fouled spark plugs too. Running a 25:1 engine will not make smoke but it will probably shorten its life. By how much? Who knows.

50:1 is the correct ratio after engines new or repaired have passed their break in 10 hours period using 25:1 ratio, use good quality 2 stroke oil, if like to use more, will depend entirely on you, but for normal cruising speeds (not racing or prolonged full throttle operations) this is the factory normal ratio recommendation to go.

Happy Boating

[captnjack]

Originally Posted by Locozodiac

There seems to be a complete mixt-up, 25:1 is for new engines for their break in 10 hours period or totally repaired ones break in period, engines will smoke more. 50:1 is the correct amount you should use all times under normal cruising speeds, will smoke much less. If you like to add more is entirely up to you, anyway use good quality 2 stroke oils and use what's ratio factory recommended.

Most older engines (70s and earlier) ran at 25:1
Since roughly the 1980s (depending on brand and incorporation of oil injection technology) engines were 50:1
Just before 4 stroke technology took off in the late 1990s, many engines were running 100:1 but strictly via oil injection.

[Locozodiac]

Originally Posted by captnjack

Most older engines (70s and earlier) ran at 25:1
Since roughly the 1980s (depending on brand and incorporation of oil injection technology) engines were 50:1
Just before 4 stroke technology took off in the late 1990s, many engines were running 100:1 but strictly via oil injection.

Yes, you are strictly right, forgot about that issue as many years have elapsed since, some very, very old engines like Sea Gull used extreme non friendly ratios. Luckyly to evironment not a single one in current use to date, the owner will prob en in jail or be shot for extreme polluter.

[Poly]

Originally Posted by Locozodiac

Luckyly to evironment not a single one in current use to date,

Still plenty of people running old 25:1 engines over here.

[Nos4r2]

Originally Posted by Polwart

Still plenty of people running old 25:1 engines over here.

Fair few on 10:1 still too

[Mollers]

Originally Posted by Nos4r2

Fair few on 10:1 still too

3/4 pint of oil per gal.

[codprawn]

Use old cooking oil - you will save a fortune!!!

[ribpilot]

Originally Posted by Mollers

3/4 pint of oil per gal.

I used to have an old dingy which had a seagull on,very reliable and started on the first pull but pollution at 10:1 left a nasty trail behind Not so bad on the sea but on the river NO.