Ok guys. I'm new to the site. I just got my hands on a 1986 lt 250r. I traded my kx 250 for the bike. The bike seems to be in very good shape. Polished swing arm new tires and rims etc. however, when I start the bike and put it in gear the bike dies. It starts fine. I pull the clutch in an put it in gear and the bike dies. Also if I give the bike throttle to keep it from dying once I have it in 1st gear. The bike starts to roll on it's on slowely forward. Could this be a slipping clutch or bad transmission.

Thanks for help. Manual will also have info on how to adjust clutch?

absolutely the manual will have all that info on there. you can also just google search it. its really the same for just about all quads just maybe  a small difference in setup. i would honestly take a look at all the stuff mentioned. you'll be shocked at what you may find to a quad that hasn't been torn apart for a long time.