The “ratty” bit is worrying, you mean rattle, right? Or do you mean bad running, as in misfiring? If there was some rattle from the engine… well that does not sound good. Are you sure it was mechanical rattle from within the engine?
I would expect the engine oil to lubricate sufficiently, even if thinned out by 1/3 with 2-stroke oil. I know of many instances when water has got into a dirtbikes engine, turning the oil white like milk, but without damage to the engine.
Hope your bike is ok. Please let us know how things turn out.
Yamaha XT600E '01, Honda XR400 '03, Yamaha XT550 '83