[ajgross]

The series 1 motors are prone to blow up if they are ran at steep angles. The rod journals are lubricated by oil falling off the cam and when you get it at a steep angle, it misses the rod that is higher in the air. The series 2 motors fixed this problem by increasing the oil pressure and lubricating the rod journals directly through the crank.

The only problem I consistently hear about with the series 2's is the crankcase filling with gas. It usually caused by either a bad fuel pump or the carb needing rebuilt.

As far as telling the difference between the 2 engines, I don't know of a way to do it accurately with out tearing into the engine. There are a couple of things that can make you lean one way or the other. The series 1 engine had a pipe plug for the oil fill. Series 2 engines had a plastic oil fill tube, but I've seen series 1's where the plastic tube was added. Also, the later series 2's have provisions for a external oil filter, but early ones didn't. The series 2 engine I have is out of a 1985 682 and it doesn't have oil filter provisions. Maybe the 1710 and 1711 engines did. Lastly, all series 1 engines have the better carter adjustable carb. But some series 2's have them also.

The only way I know of to truly tell if you have a series 1 or a series 2, is to pull the cover plate off and see if it has a oil pressure check relief valve. That was one of the improvements of the series 2.