Have an old Ariens FT314 front rototiller...small. Does it take just gasoline or does is have oil also?

You can use an old gummy oil solvent like gasoline over a wash tub. use a small paint brush, or tooth brush. Probably want to avoid fumes by doing it in the driveway. Be sure to relube the moving parts with a good quality light machine oil.

.8mm will get you sorted.

If you filled the fuel tank with gasoline enhanced with ethanol the fuel may be bad and caused the carburetor to gum up. Also Honda engines have a low oil sensor and from your description of the oil, can cause problems with the sensor and the engine won't start. Try changing the oil first and then adding a small engine gasoline additive that helps with stale gasoline starting problems.

check to see if the oil smells like gas the needle valves go bad in the carb and gas over flows into the crank case also the head gaskets go bad and **** the oil from the crank case

It probably doesn't have a factory filter, but I feel ALL small engines should have. The only fluids to check would be the engine oil and maybe the tranmission lube in the little gearbox (if it is self propelled). I don't know how STEEP the hills you mention are, but if too steep, gas flow and oil cirulation will be affected. Try going up the hill at an angle to reduce the problem.
If there is no dipstick tube on the engine to check the oil level, then look for a little yellow cap at the bottom of the engine right above the deck. It is threaded and twists on and off the engine. I think it is made of nylon.Your oil should always be clean, never black. When it starts getting dirty, change it. Most small lawn mowers hold 20 ounces of engine oil (about 2/3 of a quart).

I can't find anything on an RT 254, but if you meant RT 524, that is a rear tine tiller with a 5 horsepower gasoline (petrol) engine. That engine should not require you to add oil to the petrol. You can purchase a generic service manual which does includeyour tiller here if you like.
Or, just look for a crankcase oil drain plug which sticks out the side of the very base of the engine, and a fill plug, which is angled and higher up and usually plugged with a screw-in plastic plug. Take that plastic plug out and check the oil - in fact, if it's an old machine, I recommend you drain the oil (using the lower plug) and refill it (until it is at the level of the upper plug). In any case, this confirms you don't need to add oil to the petrol. Happy tilling! Please rate my solution if helpful, thanks.

well you should really cheek your spark to see if you are getting spark by using a screw driver in the spark plug agents the metal and see if their is an arc from the points

Try this website www.outdoordistributors.com/Tecumseh/tmain.html, it should be helpful.

I would not run it any any less that  50/1 ratio.

Sounds like you are speaking of the float bowl.
It should not have a hole in it.
You could purchase the part from Sears or a small engine shop.
If it were mine, I'd remove the bowl, clean it, and patch with a gasoline impervious material such as JB weld.