Johnson AB 25 Help

[muddog2]

Tried to start the motor tonight after I installed a fuel line and gasket to carb. I pulled about 5 times and fuel started dripping from the intake. Took plugs out and no sign of fuel in cylinders. Took carb off and took needle valve out and the screw on the bottom under needle valve out. and blew through all the openings and nothing seemed to be clogged. Should I soak the carb? If so, in what? I really don’t know what to do now. Put 1/2 tea spoon in each cylinder and it fired. Would love to go to Lake Murrey, 15 miles away, for the 4th with it running.
Thanks again for your help, Robert

[stanley]

How many turns out did you have the needle when you were trying to start it?

[Tom]

After you open the petcock at the rear of the tank does the carburetor fill with fuel? (Remove the cover to check.) If the bowl fills, and you remove the needle valve. does fuel run out of the hole where the needle valve was? If yes to these two, the jet may be clogged. Remove the screws in the passageways and blow carburetor cleaner through them, making sure that some comes out the tip of the jet which you can see from the back of the carburetor (with the carburetor off, of course).

Tom

[The Boat House]

[muddog2]

I filled up the bowel and left the pit cock valve open for 10 minutes and no gas leaked out the top. I took the needle valve out and gas ran out of the hole. I took the screws out of the side and pulled the cam out and I took the screw out of the bottom under the spray nozzle and I pushed a wire in the spray nozzle and I could see it through the small holes on the side of the nozzle. i pushed the wire through the small holes on the side of the nozzle. I put everything back together and I rechecked the points and made sure that the points begin to break when the marks on the flywheel and armature plate are lined up. Pulled the rope 5 or 7 times and noticed that gas is leaking from the edge where I took the cam out of carb. Mostly the bottom edge. Is there supposed to be a gasket there? I also noticed that gas is around the rim of the intake. The gas is still not getting to the cylinder heads. Poured 1/2 teaspoon gas in cylinders and it fired when I pulled the rope. Any suggestions.
Thanks, Robert

[stanley]

No gasket in there.Not much left to check but compression/crankcase pressure.Did you check compression?Good fly wheel bounce is a good clue.

• This reply was modified 4 years, 10 months ago by stanley.
• This reply was modified 4 years, 10 months ago by stanley.

[The Boat House]

[muddog2]

Have not checked compression yet. That is what I am planning to do next. What is the specs for the compression test? I know how to check for compression through spark plug openings. How do hyou check crankcase pressure?
Tubs, I will try your method. If anyone wants to talk my number is 803-542-4998
Thanks, Roberrt

[stanley]

I don’t have a good idea of an exact minimum compression number,the important thing is that the cylinders are pretty equal.I would think anything above 60 would be good enough to get it to start.The assumption is that if the compression numbers are good then crankcase is also.The other thing to check is for badly worn crank bearings.Try pushing the flywheel from side to side to check that.

[muddog2]

Checked compression this morning and reads 62 +/- both cylinders. I grabbed the flywheel and no movement when I tried pushing it side to side. Still not getting fuel to the cylinders. Is there something I can spray into the hole that the carb mounts on to clean the inside of the engine? I am wondering if that is where the problem is. I appreciate all the help I have received from this site. I would have never got this motor this far without everyone’s help.
Hope everyone has a great Fourth of July.
Robert Clark

[Author]

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