Evinrude 55 hp 1957

This past week I was fishing a

This past week I was fishing and on the way back to shore all at once it seemed to drop one cylinder. When I returned home I checked the plugs and they were fine. Both cylinders have good spark and the keyway is not sheared. The engine seems to run fine in a barrel but does not have any power in the lake. If you remove one wire you can tell the difference when you rehook. The compression is 85 and 90. On the water with full power it acts as if it wants to go but can't quite go to full RPMs The plugs points are new and it was timed. It starts very easily. One or two pulls. Any help would be appreciated. This one baffles me.

Sounds like the lower unit is

Sounds like the lower unit is jamming due to a broken shock absorber spring.If in fact you have spark on both cylinders that will jump a gap of 1/4" or more than you may have to bull the lower unit apart to inspect.The problem is verified when you look at the bearing housing below the pump and it will show signs of being "unhappy" if the spring is broken.So make sure you are running on both cylinders and then the above may be the problem.

Thanks for the info. I checke

Thanks for the info. I checked the lower unit it is very smooth turning. I am thinking it could be a broken reed or maybe the jets clogged. If I adjust the idle and the high speed it seems to pick-up a little RPM. This morning I drained the foot and there was no water or shavings.

I am confused on the broken sh

I am confused on the broken shock spring in foot. When I did a reseal on the LU I don't remember a spring?

"It is there but you cannot se

"It is there but you cannot see it, it is inside the " lower driveshaft ". If it breaks the assembly gets longer and jams up the works.Simple really."

How old are the coils and cond

How old are the coils and condensers? Did you replace the water pump impeller? Are you using 50:1 or 24:1 fuel/oil mixture as the factory recommends?
All of the above could be causing your problem.

Replaced everything in the ign

Replaced everything in the ignition area earlier this year. 24:1 Will take a look at parts diagram of LU to find spring. Will let you know. I'm wondering if it could be a broken reed or the jets have a partial blockage. I changed it over to a fuel pump from old style. Everything has worked fine for months then this.

Look for the lower drive shaft

Look for the lower drive shaft assemly it has the spring inside.

Thanks to everyone for posting

Thanks to everyone for posting. The problem was a leather o-ring don't know how old but since it is a 1957 probably then. Evidently it was in the air silencer assy and decided after 20 or 30 years to get itself sucked into a leaf on the reed assy and hold it open. Some info that may be helpful in future. The lower unit has one drive shaft that goes from engine to pinion gear there is no lower shaft. The shaft which contains forward and reverse gears and sync gear. has no springs except for the shift position spring

Your motor does not have the o

Your motor does not have the original lower unit / driveshaft. It looks from here that it has the later 6hp lower unit (not as good ) with only a 0.432" diameter bearing surface as opposed to a 0.550" bearing surface.We are only trying to help from far away.