1964 40hp evenrude

[oldxbiker]

my motor starts right up and idles fine. compression is ok, the carb was rebuilt 3 yrs ago.<br />when I try to run it at WOT it runs about 1/5 speed. when I open the choke cover on the engine cover the motor runs perfect or if I take the engine cover off compleatly the motor runs great.<br />What could be my problem?

 

[alcan]

Re: 1964 40hp evenrude

This sounds like you have an exhaust leak. This is where the motor is suffocates on it's own exhaust. Check the exhaust plate gaskets on the port side of the block. You may also have shroud gasket problems. There should be a short rubber hose between the exhaust housing and the outter shroud. This is the exhaust bypass port, you should find it about half way down the back of the leg. Anyway mix a test batch of fuel at 24:1 (so you get good smoke) run the motor in a tank and try to locate the leak. Let us know what you find.