Wont buy after all went to go check it out and well it was running fine 3 days ago and today he started it up and it began to back fire so I thought about it and well out of no where it just died.He tried to start again and it wouldnt turn on so we waited a while and my buddy Tom took me to go get lunch cause he owed me.So we get back to his house and try to start it again and it just wont start.So the ? is should I still get it cause I dont want to have to deal with it always brakeing down and never being able to ride or go to the track to race.

 

Pop a new BR9ES in there and listen to it perrr.

 

The backfire may be a minor problem, but it could be something that frustrates you to no end trying to figure out.
If it's an all stock 89 and the asking price is $4200, he's in the ballpark.
If it's really the machine you want, and you can get him to get it running good again, it'd be a good deal.
Make sure it's all there, frame straight, good tread on tires, rims not too bent up, plastic all there, steering stem not tweaked, etc.
Keep in mind, if you do buy it, it's going to need a top-end rebuild very soon. That means having to pull the cylinder and piston, get cylinder honed or bored, new piston/rings and new gaskets. It's going to cost you at least $150 to do this. While you have it apart, you may find you need new reeds, and a few other things.
I truly love the Rs, I think they're the greatest, but, they aren't for everybody.