Motorcycle Repair: valve adjustment on a 1982 harley sportster, harley sportster, nylock nut

Question
How do I check and set the valve clearance on this 1000 cc motor. And what do the large allen head countersunk bolts with the nylock nut on the opposite end do that are located on the heads top cover?

Answer
First telescope the pushrod tube on the lifter you wish to start with and then turn the engine over until  lifter is at the bottom of its travel. You should be able the spin that pushrod freely but have no up or down movement. If you do not have this then loosen the lock nut and adjust the lifter cup until you have the proper fit then tighten the locknut. Continue with this proceedure for the remaining lifters.