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Sorry fleetwin, I did not see your most current reply.
There were no signs of over-heating, and someone gave this motor to my friend saying, “it runs fine but gets hot”. There is no telling when was the last time the motor ran (probably 20 to 30 years ago). The first thing that I did with the motor was try to see if it truly would run. With all the problems I found with this motor it was probably given to my friend because had too many bad issues. Broke the motor completely down, cleaned all water passages, and replaced all gaskets. Tested the water flow through the motor and was now normal. Water pump was providing good pressure, but I changed the impeller just to be sure.
After restoring the water-cooling system, I then started working on getting the motor to run. Both coils were bad, one spark plug was bad, and the cork float in the carb was dried out and cracked. Re-built the carb due to the bad float, O-rings, and gaskets. Varnish on the needle valve had to be scraped off. Installed new needle valve and seat.
This is when the motor would barely run. After super cleaning the carb, the motor will now start on the first pull. Glad to get it out of my shop. I never charge for parts or labor to get old motors running again, because I enjoy it and I learn something new each time. Thanks again for the help.
Great news! Yeah, most carb cleaners of today won’t break solid gunk. Soaking them too much can lead to casting porostiy as well, so the ultrasonic is always a great option.
The thing to remember about these engines is that they normally run a bit hot. The exhaust cover is not water cooled, so it will get hot, the head gets hot as well. Temp readings are taken from the starboard side of the engine block. All that being said, they do have some small cooling passages that love to get plugged up in salt water.
Sounds like you have successfully tackled many issues and revived this nice old engine. I always liked these engines, although they didn’t idle as nicely as the 3hp models they replaced, but much more powerful. I know the factory says that 50:1 is fine, but going a little heavier is best for these engines that have “plain rod bearings”. I have seen many 4hps with holes in the block where the rods said “good bye”.
Nice work!