Certainly attending a class is a great thing and the best way BUT, if you can disassemble/reassemble a lawn mower engine without having any extra parts left over, you can do the same with a DD if armed with a few special tools and, most importantly, the DD service manual. Forget any of the chilton/clymer, whatever publications. For normal maintainance, you probably don't need special tools beyond an injector height gauge and the two valve adjustment wrenches - and some folks don't even use the valve adj wrenches. BUT you DO need the DD service manual!!
The biggest issue is that the various component parts are generally bigger and, more importantly, heavier than the same components on a smaller engine. So yanking the starter off that 8V71 is a bit more of a PHYSICAL chore than pulling one off your family car. But the process is no more complicated.
