Provision on a Rotax 503

Dear Tech Guy!
What does the term provision mean on a 503 Rotax?
Ron Purvis - Knapp, Wi

Tech Guy Responds
Thank you Ron for the great question. Provisional for the most part means it will accommodate a gear box. The early UL 503's were non-provision with Bosch breaker point ignition. The provision 4 engines fit the A and many early B gear boxes. My Chinook had a B box with only 4 mounts. The provision 4 also always had Bosch breaker points on them. The latest is the Provision 8 with the heavier crank bearings throughout the entire crankshaft along with the large crank seals on both ends and dual electronic ignition (all nice upgrades). The provision 8 was the beginning of Ducati CDI either single as on the 377/447 or dual as on the 503. There was not enough room in the cylinder head of the two smaller 377/447 engines to have dual plugs. You can tell the provisional difference by looking at the PTO end of the crankcase of the 503. Provision 8 = 8 bolt pattern for the stronger Rotax B, C, or E gear boxes, Provision 4 = 4 bolt pattern for the A gear box, Non Provision the crankcase is flanged out, this will only accommodate a belt reduction. All new Rotax engines are provision 8. This has been that way for quite some time. Snowmobile engines are non provision and do have some minor and some major differences between their aircraft brothers.