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Old 23 September 2008, 16:47   #11
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Originally Posted by Polwart View Post
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.
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Old 23 September 2008, 17:09   #12
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Quote:
Originally Posted by Polwart View Post
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.

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Old 23 September 2008, 17:16   #13
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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.

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Old 23 September 2008, 17:29   #14
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Originally Posted by Locozodiac View Post
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.
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Old 23 September 2008, 17:42   #15
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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.
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Old 23 September 2008, 17:55   #16
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Luckyly to evironment not a single one in current use to date,
Still plenty of people running old 25:1 engines over here.
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Old 24 September 2008, 13:01   #17
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Still plenty of people running old 25:1 engines over here.
Fair few on 10:1 still too
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Old 24 September 2008, 14:37   #18
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Fair few on 10:1 still too
3/4 pint of oil per gal.
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Old 24 September 2008, 15:13   #19
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Use old cooking oil - you will save a fortune!!!
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Old 24 September 2008, 16:02   #20
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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.
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