I own a 748 S from 1999: I have 66,800 km and I usually personally take care of the ordinary maintenance of the bike (oil, filters, candles) and go to the Ducati Store when it is necessary to get my hands on the distribution. At 27,000 km and 45,000 we have always checked the valves, as well as replaced the straps. On both occasions they were changed 2-3 particularly worn barbells.
I just had the distribution checked: I would have expected the usual treatment (quite expensive), instead this time only the straps changed me. Are there different intervals between belt replacement and valve play control? Do I have to trust the mechanic or demand control of the valves, knowing that I meet the opening of the head, the parade of camshafts, the replacement of barbells, etc.?
Stefano Ferrigno responds
Dear Marcello, the two operations (valve adjustment and belt replacement) follow diametrically opposite logics. The valve game, within limited deviations from the design values, does not tangibly affect the performance of the engine and, above all, is not harmful to the latter. Therefore, while its possible control can be included among the routine operations, the relative adjustment can instead be carried out at the necessary time, that is, only when it is really necessary (great deviation from the expected values).
It so happens that for limited mileage, the canonical 20,000 Km, it is rarely necessary to make the recovery of the valve game, while surely around 50,000 km it may be appropriate to get your hands on the calibrated thicknesses. The discourse for the straps is different: their useful life, with a wide safety margin, is 20,000 km, routes that I personally consider mandatory their replacement.
Turning with a valve that does not close or open perfectly, in fact, does not involve great dangers, while a strap that should suddenly be damaged could decree the end of the thruster. Therefore I recommend the replacement of the straps, regardless of mileage, every two, maximum three years, especially if the bike stays stationary for a long time.