RE: OS 15 LA or Magnum XL 15?
The LA series was designed to be a cheap OS for people who didn't want a more expensive engine, but still wanted to say they had an OS. OS succeeded in building a cheap engine, but it's not really inexpensive. And they are ABN.
They do what they are designed to do, and they can be made to scream.
Because of the way they are made, there are limited repairs possible, when the crank bearing wears it's time to toss it.
The Magnum engines are entirely different. They have true chrome liners, and ball bearings on the crankshaft. In theory, the Magnum should outlast any LA engine, and still can be given an overhaul when it wears out.
The LA 15 may well be stronger than the Magnum 15, they cost aboout the same. But I really think the Magnum will be giving its lesser power long after the LA has been given a permanent home in the trash bin.
Bill.