Post Number: 1337
|Posted on Saturday, January 21, 2006 - 11:53 am: ||
The following question came in by email:
A friend of mine has just bought a launch powered by I think a 4hp Stuart Turner.
He is not sure of the oil /fuel ratio.
Would it be the usual 10 to 1 mix or with the modern 2 stoke oils a little more or less?
Many thanks for the help.
Post Number: 315
|Posted on Saturday, January 21, 2006 - 07:27 pm: ||
I have never seen a "Stuart Turner" (except the small steam model engines). On my 2 cycle Emmons AKA Stanley, I put a new set of rings on it and decided to use Amsoil synthetic 2 cycle mixed 6oz for 2 gal gas. I think thats about 40:1. It ran great, no smoke no problems. I think I would not use any modern oil at 10:1. If you have to use a ratio like that somethings wrong.
Post Number: 175
|Posted on Sunday, January 22, 2006 - 05:26 am: ||
Mix is 50 to 1 (petrol to oil). It's much higher that the traditional 25 to 1 mix foir many other 2 stroke marine engine due to the higher compression crankcase - a hallmark of the high standard of engineering with the Stuart engines
Richard A. Day Jr.
Post Number: 524
|Posted on Sunday, January 22, 2006 - 12:48 pm: ||
I am of the opinion from talking with an individual some years ago that specialized in lubrication problems for industry that the two stroke oils developed for weed whackers, chain saws, and similar high temp burning and swept piston speeds were not a good solution for the classic old time two stroke for two basic reasons. Those engines run very cool and therefore the oil was not consumed in the burning process and it tended to build up the carbon/oil deposits in the upper chamber. Second because the oil was not almost totally burned up it went down the exhaust pipe and tended to create a much too oily wake. The classic marine engine oil mix starting about 1909/10 was 40:1 with oil we today call SAE 30 non detergent. I know Ernie has sworn by 30:1 useing modern two cycle oil and had no problems with it. So I guess you take your pick and have at it.
Pre WWII we ran our motorcycles with SAE 75 and our model air plane engines with SAE 75. I must admit I forget the mixture. We also used AMOCO white gas as it had no lead in it. Of course the lead is now long gone from gasoline and the new loser is the cork float when gasoline with ethanol in it attacks the shellac on the cork floats. Just can seem to get it right can we!!!
When 50:1 came on the market it seems to me you were supposed to use special oil that was designed for that ratio. Now of course the two stroke is facing near extinction in operational use in marine applications and even lawn mowers. So where do we go from here??? Anybody that runs their classic Maytag at 16:1 knows they instantly become unpopular at engine shows when there is no breeze. It seems to me that there is an application the 50:1 modern two stroke oil should be very useful with the Maytag high temp cylinder and relativly high swept piston speeds when compared to their historically contemporary marine cousins.
Post Number: 288
|Posted on Sunday, January 22, 2006 - 05:26 pm: ||
Roger.........The fuel recipe is one third of a pint of oil to 2 gallons of petrol. So you can convert to Metric or reduce one 6th of a pint to 1 gallon .
Oil ....I have used both ,the modern two stroke mix and the straight SAE 30 engine oil.
Never had any problem with either.
|Posted on Sunday, August 27, 2006 - 01:07 pm: ||
i have an R3M, and the oil mix mentioned above is the correct one. One third of a pint to two gallons works out at 48:1, 100ml of oil to 4.8 litres of petrol. I have been using a synthetic two stroke oil, and this was fouling the original spec spark plugs. I solved this with the use of a chansaw plug, a champion CJ7Y. My engine is not in a boat, i use it for rallies, and it uses as much brasso as it does petrol!
Feel free to contact me regarding this engine.