Setting up a valve adjustment on an air-cooled flat-four is straightforward and should be done every 3,000 miles or every season, whichever comes first. The valves affect both performance and engine longevity.

The procedure is identical for the 1200, 1300, 1500, and 1600cc engines. Cold adjustment, engine off, with the specified clearances — typically .004" intake and .006" exhaust on the later engines, though always verify against your specific year's specification. The feeler gauge should drag slightly, not pass freely and not require force.

The pushrod tubes are the common leak point on air-cooled engines and should be inspected every time you do a valve adjustment. A leaking pushrod tube will deposit oil on the exhaust and eventually create a fire hazard. Replace the seals with fresh ones — they're inexpensive and the job is quick.