1991 Yamaha 350 Warrior - Rear Tire Tubeless?

[83BMichigan]

Are the rear tires on these tubeless? I bought one super cheap today knowing the rear tire has a slow leak. 
Any insight is appreciated. 

[Mech]

If you look at the tyre valve it will be either metal, threaded, with a nut to prevent the tube pulling in, or an all rubber valve which is a tight fit in the rim's hole. The metal one is a tube.

I'd imagine it was originally meant to have be tubeless.

There is stuff they call "slime", that you buy in a bottle and put into tyres to stop slow leaks. The slow leak could be between the tyre and the rim, so you'd want to take the wheel off, take the tyre valve out, put the slime in and then the valve back in, inflate the tyre, and hold the wheel on it's sides and roll and flip it around so the slime gets right up the sides near the join between the rim and tyre. You need to roll and flip it around at the right speed and timing and angle to get the slime into the right place. It will be a bit of hit and miss to get it all the way around the the join so you need to take your time and work the slime around for a while. It would help to locate the leak before you do all that, to get the slime into the place it's needed, by putting the inflated tyre into a tub of water and looking for bubbles. If the leak's in the tread part of the tyre then it will seal itself when you ride the bike.

A bottle of slime is about the same price as a new tube, but often a better option. Once it's in there it will seal any small leaks you may get in the future. Also, the rims that are made to be tubeless have the hole in the rim in a place that does not suit the tube's valve, with the result that if you do use a tube, they can easily get destroyed if the tyre does go even slightly too flat on a ride.

[83BMichigan]

It’s tubeless and the term “good deal” is always short for “good deal of problems to fix”. There were to nail type holes that I plugged. 
I’ll probably get new tires for it next year since two plugs isn’t ideal, let alone one. 

[Mech]

On the slime bottle they claim it can fix the hole left by a four inch nail... I've only used it to seal rusty rim to tyre leaks though.

There are various brands but the one called "Green Slime", seems the best..  It's thicker and gooier(if that's a word!)