Is lauson rsm really a marine engine.

[James R]

I have a lauson rsm 825 # 7-41334,I have learned it is a marine engine,I was wondering how I can find out what type of boat/application was it used for?.
The motor came with an old boat I bought years ago but was it ment for this boat?( I don't know the history of the old boat) .
I am sure this type of information get lost along the way but I thought I would ask,thanks

[Doug Hudgel]

Lauson did make a four stroke outboard, is that what you have?

[Andrew Mackey]

Lauson actually made 2 4 cycle outboard units. I worked on one of the twins, an opposed 2 cylinder, air cooled. it had one carb, and ran quite well, but was noisy as all get out. It used the short screw in mufflers. As I remember, it was not too well balanced either - it vibrated like hell, but it had plenty of power.
Andrew

[bill chasser]

Yes your RSM is an adaptation of an RSH/RSC. The "M" designates it as a marine engine. I can't tell you specifically what makes it marine except it will probably have a crankcase base with an extended sump for increase oil capacity. I recently purchased a TLM which is a variant of the TLC/TLH. Mine is equipped with a rope pull start, a special cast oil pan with a sump that is angled as to fit the keel of a boat. These engines were used as direct outdrives and could be fitted with a in/out transmission and or possibly a reverser. They would have been installed in small boats probably not larger than 12-14' built from the late 1930's and into the early to mid 1950's. I'm not a lauson specialist by any means but I have several tlc's configured for motor scooters and the one Marine that I bought for parts. When I got the motor it was complete and had very little grunge on it. After a very brief look over and a quart of fresh oil in the crankcase, it fired right up on the second pull after cleaning the points with a grocery bag. Original in all respects, it looked like a screwdriver had never been put to any part of the engine. Even the oil fill cap hadn't had any wrench gouge marks. Too nice to part out so I will keep it intact. I believe the rs series engines are smaller than the tl series. The tl's are rated at 2.3 hp for the scooter. Your year of manufacture is 1947 based on the serial# starting with 7-xxxxx I cant find a way to post pics in my reply but if you wish some let me know and I will start a new thread(?)