Diesel in a gas engine.

I think I may have put Diesel into my engine a few weeks ago. Is there anyway of knowing whether or not I did this. Weird question, I know.

Pull a fuel sample and have it tested at a lab. You may be able to have it tested through your auto parts store if they offer this kind of services.
Other wise, get the fuel blend out and start out with fresh gas to be on the safe side and before any adverse affects happen. Us the blend in your push mower or bon-fire starter.

I've been riding it for a few weeks and put regular gas in it twice since then, would a fuel test still work.

The fuel test would still shows signs of the fuel contamination, however the fuels will separate after sitting a while. the diesel will remain on top and will not get picked up until the fuel gets low. Chances are that if you have not relized any adverse affects to this point you may be alright.
The other option to have the fuel tested, is your local fuel delivery Co. or shake the fuel up, take a fuel sample in a clear jar and see if it separates over a period of time.

The fuel test would still shows signs of the fuel contamination, however the fuels will separate after sitting a while. the diesel will remain on top and will not get picked up until the fuel gets low. Chances are that if you have not relized any adverse affects to this point you may be alright.
The other option to have the fuel tested, is your local fuel delivery Co. or shake the fuel up, take a fuel sample in a clear jar and see if it separates over a period of time.

Just my opinion here..... I have drained several fuel tanks where gasoline and diesel have been mixed.... and there never was any sign of separation, regardless of how long they sat.

Diesel or gas and water will seperate, but diesel and gas will stay together.

Liquid petroleum products pretty much never separate on their own. They will stay mixed. You can mix gasoline with oil, diesel etc and you will end up with a homogeneous liquid.

The only way to seperate them is through distillation, which really is a form of evaporation. If you let a gas and diesel mix sit in an open container, the more volatile hydrocarbons, (which are gasoline components) will evaporate first, leaving a liquid that is mostly diesel fuel.

Imo if your car runs and drives fine, and you have already reliffed it a couple of times with gas, then do not worry about it. If there was any damage donw, you would have noticed it by now.