What is the correct fuel oil ratio for a ryobi lawn geni mk II i am trying 25:1 as this is an older machine but wondering if this machine runs at 50:1 as it is four strokeing. i need to know the correct fuel oil ratio before tuning thankyou

Buy a 2-cycle oil of your choice and mix it according to what the oil says to mix it.
You'll be OK.

I would go with 25/1, as that is always going to be safer than 40/1, too much oil might make a bit more smoke, but the engine will be happier. Too little oil and you risk bearing damage, or even worse, engine seizure.

For two stroke engines of this capacity the ratio of fuel to two stroke oil is (25:1) 25 fuel to 1 (two stroke) oil. Eg 200 ml of two stroke oil to 5 litres of fuel.

Most Ryobi products made in the past 5 years use a 50:1 fuel mix. Check the fuel cap to see if it is listed there. The older Ryobi product used a 32: 1 fuel mix ratio and it was usually listed on the sticker that shows you how to work the choke. If in doubt, go with the 32:1 ratio. The only thing it will cause is premature fouling of the spark plug. Too little oil in the mix will cause premature engine wear.

50:1 is 2.6 ounces of 2 cycle mix to each gallon (U.S.) of gasoline.
32:1 is 4.0 ounces of 2 cycle mix per gallon.

I recommend to use a 2 cycle mix that is specifically designed for lawn equipment and contains fuel stabilizer. The ones with stabilizer will usually be .5 ounces larger.

Good luck!

Check the fuel/oil mix ratio you are using. Some Ryobis use a 32:1 mix and some use a 40:1 mix. There isn't much difference there. To be on the safe side, if you machine is possibly running or tuned a little "lean" I would start off with about 4 oz/gallon oil to gas mix. Use synthetic 2-stroke oil also. Your machine will perform much better.

some of these machines are 40:1 and some are 50:1 please check your owners manual,or ask the shop where you bought it,be very careful as the incorrect mixture can damage the machine,rgds

I did finally find the owners manual and it told me everything that I needed to know. The correct mix is 25:1.

http://odref.com/pdf/Ryobi/
If you have your model number, an owners manual should be here with correct mixture ratio for petro to 2 stroke oil.

Hello slabieniec:

The Newer 2 Cycle Trimmers use a 50:1 Ratio (OEM Suggested Ratio). I Use a 40:1 Ratio in Most of my Equipment, Except for Chainsaws and Hole Drillers/Augers. For the Chainsaws I Use a 32:1 Ratio and the Hole Digger/Auger Uses a 25:1 Ratio.
Please, Do Not Hesitate, If you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance.
Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Be Happy. Thanks.

Good Luck

Respectfully

jbridger (John)

25 to 1 = 200ml of 2st oil to 5 lt ulp

OR I use 150 ml "stihl" 2st oil to 5 litre of ulp Less smoke and better oil.