| This is a difficult question to adress as belts snap for a variety of reasons.
In automotive appications toothed belts fail for the following reasons.
1, exceeding design life in mileage or time
2, damage due to contamination (oil dirt nuts bolts etc)
3, incorrect tension
4, wear in pulleys, tenioners etc
5, manufacturing fault
I run a car workshop for a living and as a result of my experiences I always change belts at 1 year/12000 miles whichever is sooner, But I am aware that even camshaft drive chains have snapped for no apparent reason. Ducati now use toothed belts which are good quality and very strong but they chose to reduce the width of the belt compared to normal practice as the loads are lower when the belt is not having to compress valve springs.
Ducati made a cost/weight/life compromise and specify a replacement period based on that decision. The reccomended replacement mileage is different for some models this relates to type of use and rpm/load variations.
998 testastretta and 749/999 models have slightly different routing of the belts which should have extended the life of the belts(or reduced the risk of premature belt failure).
I know this does not adress the initial post but hope it sheds some light on the need to stick to the reccomended intervals remembering it is mileage or time WHICHEVER IS SOONER
dave  |