I recently picked up a used 1987 XL600R that has been sitting a while. I'm still sorting out and cleaning the carbs and gas tank, and replacing some of the rubber parts as it's been sitting for over a year. Any tips or instructiosn for adjusting the valves and checking the valve timing (without the engine running). I have heard that the timing chains older XR/XL's have a tendency to slip. Thanks in advance for the help.