I am at a loss at where to go from here. I've almost exhausted everything I can think of. I'm not a mechanic and don't have a lot of experience. I can be resourceful and follow directions when I need to though . I got a 25R70E - 25hp Johnson Seahorse from a guy near me for a decent price. He told me that it probably just needed a rebuild on the carb :rolleyes: (yeah right). I really wanted it because I already have a matching 1970 6hp Seahorse family heirloom that runs like it's brand new. When I first got the 25 home I could get it to fire occasionally but not start.
Compression on the cylinders after a good cleaning with seafoam was 115 on both. Yay! Checked the spark plugs and they were both firing , but I discovered they were the wrong model. I checked all the cross-references and they were definitely not the right ones. Replaced the plugs with correct ones and got it to hit and sputter a little more.
Pulled the flywheel off. Condensers, Coils, and Wires checked good on the ohm meter. The points looked... weird. They looked almost new. I discovered they were the wrong set for this motor and were bent to achieve the gap. Replaced the points, set the gaps. Motor would now run a little bit, but very hard to start and smoking like crazy. Bottom spark plug was black and wet, top one was black and sooty.
New fuel pump. No more wet bottom plug. Still running crazy rich though.
I decided to make sure the water was flowing so I wouldn't overheat it. Gearcase was full of muck, so I fully cleaned it out and replaced the seals. The impeller was mostly together, just two fins broken off - replaced.
Rebuilt the carb. I took it fully apart and checked every passage. It was already very clean and the replaceable parts looked new. The only gunk I could find in it was just some mild debris behind the metal plugs. HOWEVER... I noticed that the hole in the old needle seat was larger than the one in my new sierra kit (18-7222).
I'm thinking that somebody cludged together parts without doing any research and something else may be the wrong part number. The carburetor is definitely used and in good shape, but I wonder if it was taken off another motor. I wonder if it has the wrong size jet in it. I don't know what else to do. The power head looks like it's never been opened, as far as I can tell. Any suggestions?
Videos!!!
Compression on the cylinders after a good cleaning with seafoam was 115 on both. Yay! Checked the spark plugs and they were both firing , but I discovered they were the wrong model. I checked all the cross-references and they were definitely not the right ones. Replaced the plugs with correct ones and got it to hit and sputter a little more.
Pulled the flywheel off. Condensers, Coils, and Wires checked good on the ohm meter. The points looked... weird. They looked almost new. I discovered they were the wrong set for this motor and were bent to achieve the gap. Replaced the points, set the gaps. Motor would now run a little bit, but very hard to start and smoking like crazy. Bottom spark plug was black and wet, top one was black and sooty.
New fuel pump. No more wet bottom plug. Still running crazy rich though.
I decided to make sure the water was flowing so I wouldn't overheat it. Gearcase was full of muck, so I fully cleaned it out and replaced the seals. The impeller was mostly together, just two fins broken off - replaced.
Rebuilt the carb. I took it fully apart and checked every passage. It was already very clean and the replaceable parts looked new. The only gunk I could find in it was just some mild debris behind the metal plugs. HOWEVER... I noticed that the hole in the old needle seat was larger than the one in my new sierra kit (18-7222).
I'm thinking that somebody cludged together parts without doing any research and something else may be the wrong part number. The carburetor is definitely used and in good shape, but I wonder if it was taken off another motor. I wonder if it has the wrong size jet in it. I don't know what else to do. The power head looks like it's never been opened, as far as I can tell. Any suggestions?
Videos!!!