How would an XR600R compare to a 250?

Compared to your CR250, it'll feel like a gigantic truck of a motorcycle, with tons and tons of torque.

and a couch cushion for a seat...

Does your 2 stroke ever do this... you're putting up a narly rooty hill climb, because you can- not because you have to, and your back end slips off a root to the side - you lose traction and then it grabs. The bike jumps out from under you and you lose grip of the throttle. The bike at idle and in gear continues to plow until crawling its way up the side of the rut and into the bushes were it finally dies and you hope to god it doesn't fall over and crush you beneath its 300 pounds. The torque on these big thumpers starts down low and doesn't let up.

The 86 you describe is a good year because many improvements were made from the 85 that I have. A quick release air box cover, aluminum swing arm, fancy digital odometer, and it's a 600. The only "old bike" items are a rear drum brake, dual carbs, and a 17 inch rear wheel. None of these are a problem.

If you can get the rear wheel to hook up when you open up those carbs then you will have a white knuckle experience. You can ride 60 trail miles on half a tank.

Yup, it'll feel like you hopped off a mountainbike and onto a Harley. I owned a '00 CR250, & prior to that rode a '92 XR600 (a few updates, like rear disc, better forks, don't know what else). For lazy trail riding, there's not much better. Cushy seat is an understatement. You'll be amazed at how low the revs can go before stalling the thing, then you don't even need to bother feeding it a little clutch- just twist the throttle & it picks up speed steadily. It'll scoot you along pretty darn quick, too. Starting them is friggin' tough. I rode one for almost a year & never really got the hang of it.

I borrowed one for a race one time just to see how it would be while my bike was down. I stalled 3 turns from the finish and lost 2nd and went back to 3rd. The thing had a 5 gal. gas tank that made racing a little weird and a dualsport kit. Had a blast with the horn!! Even used the turn signals a few times when passing friends. Like a big block sofa. They should however put highway pegs on them, my feet kept getting caught in the ruts.

I always wondered how Summers kept that thing going sooo fast.

That XR would be a gas. But I hope that you are a strong dude! The Big Bore can take some manhandleing. The XRs are about as bulletproof as you can get. My 84 XR250R ran hard for years. I think that I replaced 3 rear tires, both sprockets, and changed the oil every now and then total cost of maint... under $300. I had it for 12 years! Then I sold it and last year the guy freak'n passed me on the trail with it! He said he hadn't changed the oil in 2 years! I think these bikes ride better when they have a few hard/wet miles on them.

Rhino