Filling your 2stroke tank

[TSB240]

I wouldn't worry too much, in my Mariner manual it's suggests 25:1 for initial running-in, the test is as follows: When you start the motor if you can still see the boat the mixture's OK....

Like the idea of 100ml bottles too.

At home I have two stroke chainsaws and hedge cutters. I bought a few 100cc bottles of two stroke oil for these and re use them as measures for the OB. (Keep them wrapped in a clean polythene bag to avoid getting any contamination in the fuel)

 

[oldharry]

Digital kitchen scales, fill a plastic cup with water to whatever amount of oil is needed then a sharpie mark on the side of another plastic cup at the same height.

Sounds a bit involved but the kitchen scales are used for 2 part paint so all the bits are to hand and takes just a moment.

Ratio is by volume not by weight. 1litre of oil does not weigh the same as a litre of water. It may be close enough but I wouldnt risk it. Petrol for example is only 4/5ths the weight of the same volume of water i.e a 5 litre can of petrol is only 4/5ths the weight of the same can filled with water. Your engine is likely not getting enough oil as oil is ligbter than water. it floats!

Paint mixis often by weight, not byvolume,because it is easier to measure accurately.

 

[NickRobinson]

Ratio is by volume not by weight. 1litre of oil does not weigh the same as a litre of water. It may be close enough but I wouldnt risk it. Petrol for example is only 4/5ths the weight of the same volume of water i.e a 5 litre can of petrol is only 4/5ths the weight of the same can filled with water. Your engine is likely not getting enough oil as oil is ligbter than water. it floats!

Paint mixis often by weight, not byvolume,because it is easier to measure accurately.

I think what was meant was that water will be accurate to mark the container as 1cc=1gm exactly with water. (blame Napoleon..)

When replaced with oil, the weight will be less, but the volume correct...

 

[VicS]

Ratio is by volume not by weight. 1litre of oil does not weigh the same as a litre of water. It may be close enough but I wouldnt risk it. Petrol for example is only 4/5ths the weight of the same volume of water i.e a 5 litre can of petrol is only 4/5ths the weight of the same can filled with water. Your engine is likely not getting enough oil as oil is ligbter than water. it floats!

Paint mixis often by weight, not byvolume,because it is easier to measure accurately.

If you weigh the oil in grams, rather than measure the volume in cm³ without correcting for the density you will actually get slightly more oil.

So 100g of oil in 5 litres of petrol will be a little more oily than a 50:1 mix by volumes

The density of a typical TCW3 oil is 0.875 so 100g will be 114 cm³ Therefore 100g in 5 litres will be approx 44:1

 

[ghostlymoron]

I keep premix in a clearly labelled 5l container '1/20' (seagull). I use a washing liquid 'bubble' to measure it's marked on the side which makes dispensing reasonably accurate and there's always a ready supply in the laundry room.