Lauson Sea King Outboard S353 serial 3744 4stroke

[joesnuffy]

#211722

Thanks for any help in advance. I have been gone a while and wanting to get back into tinkering on outboards.

I was needing some information on this outboard if someone could help I have never owned one before. I think it is a 3HP not sure though. Also on the starting instructions it says to change motor oil every 20 hours but does not tell what type or how much. I was wanting to know how much motor oil should be in it and what type/weight. It also says to use Mobile Marine Grease in the lower unit not sure what that is?

I took some pics

Here are my questions on it. Any help is greatly appreciated.

1. What should valve gaps be for exhaust and intake valves?
2. Can a new or NOS Tecumseh head gasket be purchased and if so what part number?
3a. What type and how much motor oil? how often should I change it?
3b What type of gear lubricant?
4. The spark plug that was in it was a H11 not sure but that sounds a bit on the hot side I cleaned the points and the coil looks to be one of those some people refer to as a Forever coil it has like over 1/4 inch of spark jump but I will need to change the ignition wire. So what type Spark Plug would be best to run?
5. The screen for fuel filter in the fuel tank is bad can someone recommend some I could replace it with or a process to make a small screen filter for inside tank?
6. It has good compression when I pull rope but I haven’t tested it yet with a tester but could someone tell me if a new or NOS set of Tecumseh rings be substituted and what would part number be?

Thanks,
Joe

[Buccaneer]

#211735

The S351 information I have recommends Champion J-8 Spark Plug. I presume the S353
is the same, but maybe someone will know for sure.

Valve clearance is shown as .008 to .010. Doesn’t say, but I assume that’s set with engine “cold”.
If more than .015 valve should be replaced.

Gear lubricant now days would be Lubriplate 105 or John Deere Cornhead grease. I prefer the later.

30 W oil, change every 20 hours of operation.

100 mesh brass screen works good to make a new screen. I bought mine on EBay. I guess some
hobby stores have it. If you search the forum, you should fine examples on how to make a new
screen.

I don’t know about the Tecumseh parts numbers.

Prepare to be boarded!

[frankr]

#211737

Oil capacity is two pints (one quart)

[joesnuffy]

#211743

Thank you guys for the help.

Joe

[joesnuffy]

#212144

Thanks Guys,
She is a runner even more quiet than the video sounds a very slow idle. Just wish I had the lower cowl that goes on the motor and its also missing the air cleaner box or silencer never seen one before so I don’t know what it looks like.

Thanks

https://www.youtube.com/watch?v=Fz2mWohYoQY

• This reply was modified 3 years, 8 months ago by joesnuffy.

[Buccaneer]

#212145

Glad to hear you got it running, but I was not able to get your link to find the video.

Prepare to be boarded!

[joesnuffy]

#212154

Thanks video should work now.

[Buccaneer]

#212164

Wow, sounds like a fine tuned Mercedes!

Prepare to be boarded!

[joesnuffy]

#212183

I was amazed how slow it would run and the smoothness of it since its a 4 stroke their is virtually no vibration. At idle it is like a whisper about a 1/4 of the sound the video makes it out to sound like and its not even in water. I got 2 of them the other one is missing the recoil starter assembly but I think I will fix it also just use a rope to start it. I picked them up for like 40 bucks super cheap can’t remember exactly what I paid but I think I will keep one on my little 14 foot aluminum fishing boat which stays on the lake for troll fishing and if it gets stolen I wouldn’t be out much. When I rev it up it sure feels like more than 3 hp it does have a cylinder head on it that looks to be higher compression unlike the ones I saw as a boy on Tecumseh lawn mower engines the plug screws in near the intake valve on a slant and its not located in the center of the cylinder. Can’t wait to see how it pushes the boat.