poor performance on water

[hwcd24]

I have a 1971 evinrude 125. I have had several problems with this motor but am unwilling to give up on it. It seems when I run the engine with the muffs it operates just fine, but the minute I put the boat in the water it idles very rough. I will put it in gear and the motor barely chugs forward and then just dies out after a few minutes. I had it on the water working fairly well last week then I spun the prop hub. I did drop the lower unit to replace the impeller between the time it ran well and now. I have noticed mores water spraying out between the exhaust housing and the lower unit. could a bad lower exhaust seal cause my motor to operate like this while it is submerged. also can anyone give me an idea on adjusting the low spped needes on the front of the carbs. the manual doesn't specifically say what the initial adjustment should be (ie. one turn out). <br /> I have replaced the following over the last 2 months:<br />water pump, fuel pump, plugs, wires, timing sensor, ign coil, starting solenoid, electric choke,fuel tank and hose,inspected leaf plates (perfect, cleaned carbs, synched the throttle and distributer.

 

[Joe Reeves]

Re: poor performance on water

(Dual Carb V/4 With 4 (2 each carb) Slow Speed <br />Adjustable N/Valves)<br /><br />The adjustment procedure of the carburetor slow speed needle valves follows. NOTE... if the needle valves turn too freely, replace the nylon bearing retainer (the nylon item at the front of the carb that the needle valve goes through first) with the newer type RED retainer #315232. If your engine has that weird linkage that connects all four of those needle valves, the newer RED retainers will enable you to discard that linkage. The RED retainers make it impossible for the needle valves to viberate out of adjustment. <br /><br />(Carburetor Adjustment - 2 Slow Speed Adjustable Needle Valves, each carburetor) <br /><br />Initial setting is: All (4) Slow speed valves = seat gently, then open 1-1/2 turns. <br /><br />Facing the carburetors, start with the top left needle valve, then the top right valve, then the bottom let valve, then the bottom right valve. It may be necessary to redo these steps to get the adjustments ideally set <br /><br />Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. <br /><br />Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting. <br /><br />Do not attempt to gradually adjust all four of the valves at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve. <br /><br />When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[hwcd24]

Re: poor performance on water

Hey thanks for the adjustment procedure. Any thought on the other part of my problem?

 

[Joe Reeves]

Re: poor performance on water

If you're speaking of the water spray, That is simply a metal to metal surface which uses no gasket. I apply Sealer 1000 to the lower unit surface a minute or two befor I install it. This squeezes out somewhat and seals that area. It doesn't hurt anything to let that water spray out, and eventually it will seal up with debris, salt, etc.

 

[hwcd24]

Re: poor performance on water

I was trying to find out if the lower exhaust seal being bad could cause my motor to run poorly on the water. Like I said it runs perfectly smooth out of the water.

 

[Joe Reeves]

Re: poor performance on water

Do the basic checks. Compression on all cylinders should be approx 100+ psi and even. Spark (with the s/plugs out) should jump a 1/4" gap on all cylinders with a strong blue flame.<br /><br />The timer base under the flywheel should slide smoothly, through its range from idle to the full throttle position, up against the rubber stop on the full spark advance screw. If it sticks, it would be running at a retarded spark setting.<br /><br />If the three items above are okay, that leads back into the carburetors.