Hi guys.I have a 1956 Johnson sea horse 35. Last year the motor ran great but this year on our fist couple fo times out there seems to be no top end to the motor. It starts fine and runs really well. But when you give here full throttle it feels like its only getting the power of half throttle.I checked the plugs and I get spark on the top plug on the motor but the bottom one doesn't seem to show any spark. I switched the plugs around and even put new plugs in with no luck.My father in law thinks that the bottom plug is only for the top end. I don't think this could be true.Do I just need to check the points or maybe clean the carb?What would be a good starting point?Sorry for the long post.Thanks,Matt
I am having the same problem with my 1956 30hp. I went to the gas tank and slowly released the cap. At a certian point it took off like it should. This is why I am done with pressure tanks and want to convert, but I dont know where to draw vacuum from.Jeff
ZOOMAN, Your problem is in the magneto, you should have a strong spark to both cylinders. On an engine of that age, I would give the magneto a complete over-haul with coils, points, condensers, and if needed, plug wires. That should but it up, and running again.Larsen: If your engine takes off when releasing the fuel cap, the carb is probably flooding because of a worn needle, and seat. The carb is the problem, not the fuel tank. Opening the cap would bring the engine to a stop as the carb ran out of fuel. For a brief time the engine runs properly when you open the cap, as the pressure is no longer flooding the carb.
ZoomanR.Johnson has hit the nail on the head for you. Buy yourself an manual of at worst the clymer's repair manual and rebuild that whole magneto coil points condensor and wires. You will be happy that you did. You will prob. find that the coils are cracked if they are red they are the originals. Think about how many years have they been in use? Now you can get better coils for not much $. I just did my 57 Sportwin and after the mag rebuild it runs real nice. It will go for another 50+ years. You may want to take a compression check just to make sure it is worth the $'s to rebuild.Check out this link http://www.maxrules.com/fixtuneitup.html Good luck! Have fun!