I bought this old bike so I could have fun, and so far it's just being frustrating. I'm going to regale you all with the whole story to see if you can give me any advice.

I bought this old XT 600: it was running and riding well. I took it out on a trail and it did great except for being really hard to start when warm. The next day, I started it up and it ran fine except that it idled really high after it warmed up, so I figured I have an intake boot leak (and one of them is pretty much shot, so I think I'm still right about that). It also became increasingly difficult to start.

I took it apart and did all sorts of stuff: cleaned the carburetor (which the previous owner told me is stock except for a bigger idle jet), fixed a sticky choke lever, adjusted the valves and decompression cable. It was still a pain to start, but I did get it running. I replaced my rectifier and my ignition coil (which had absurdly high resistance) and I've now got a good spark when kicking it, but it's almost impossible to start. I couldn't get it running today.

I'm not an expert with carburetors, but I think I got everything pretty well cleaned out and running properly. I know my fuel mixture needs adjusting, but I'd still expect it to start. Later today, I think I'll spray some starting fluid in there and see if that makes any difference, but I could really use some advice, if y'all have any.

What am I missing? What do I check?