In '83 the XR500 got the "new" RFVC motor. These earlier RFVC motors tended to be a little hot headed, and in some cases ended up cracking from the exhaust valve seat to the spark plug hole. Also some of the earlier big XR's had gearbox problems. If you can stretch the funds aim for an '88 XR600, even better yet a '91 or onwards as they have the Cartridge forks, Piggy back shock, and rear disc. I'm not entirely sure if the XL's followed suit with the XR's as to the engine changes.