25cc trimmer gas ratio mixture

This small engine needs a 40:1 ratio. Use only 2 cycle oil, not motor oil. If you are mixing one gallon of fuel use 3.2 ounces of the 2 cycle oil. This should give correct mixture so you do not get lots of smoke when you start. Take the time to measure. Note: there should be a marking somewhere on the engine about the mixture.

Hello there
Download here friend.
http://manuals.homelite.com/system/files/4262/original/UT40502_UT40903_041_eng.pdf?2011


Page 8 of the Homelite user Manual gives you the EXACT ratio.
FUEL MIXTURE

'This product is powered by a 2-cycle engine and requires
pre-mixing gasoline and 2-cycle lubricant. Pre-mix unleaded
gasoline and 2-cycle engine lubricant in a clean 1 gallon
container approved for gasoline.
Recommended fuel:
This engine is certified to operate on
unleaded gasoline intended for automotive use.
Mix Homelite Premium Exact Mixlubricant with gasolineaccording to the instructions on the package. If Premium Exact Mix lubricant is not available, use a high quality synthetic 2-cycle engine lubricant, mixed at 2.6 oz. per gallon (US)'

Hi anon the mix ratio is 50:1. That's five litres of unleaded and 100 ml of 2 stroke oil

50:1 five liters unleaded petrol and 100ml 2 stroke oil

The specs say 40:1 so 3 - 3 1/2 OZ of 2 cycle oil in a gallon of gas.

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.

If you use a synthetic 2-stroke oil, you can easily get by running a 40:1 ratio mix...that is 3.2oz oil/gallon of gas. A richer oil mix won't hurt either (say 20:1 (2X the oil of 40:1). I recommend synthetic always be used alongwith Stabil fuel treatment because after about 30 days, gas loses its volatility and begins to breakdown without it...causing fuel problems.

2 cycle? then 40:1 gas to oil mixture

50:1

I had this same problem, would run a couple of seconds, stop, and you couldn't start it again.
Had good gas/oil mix 50:1 and 25cc Homelite. Had replaced the fuel filter, gas, spark plug, and took carb apart and cleaned with carb cleaner and primer bulb worked fine. None of that fixed it. What did? Take the muffler off and see if it will start and run with the muffler off. If it does, chances are the muffler is clogged. Also check the exhaust ports and clean them out if plugged with black oil carbon residue.
My muffler was clogged up, took it off, cleaned out the exhaust ports, there was some oil that was in the muffler(oil that didn't burn during combustion). It now starts and runs like a champ on first or second pull.