Mercury 20 hp 1977?

[OFF SIDE]

Recently I purchased a Mercury 20 hp, 2 stroke motor. The serial is number, 7132777. I got that the last two digits 77 are the year, 1977.
The serial number when doing a look up is not recognized when searching. Each cylinder has 100 psi, however when pulling the cord its very difficult, maybe one complete stroke, about 20" of rope.
Is this normal for these older outboards? The flywheel spins good, lots of spark however difficult to pull. The motor appears to be in good shape doesn't look abused.
Tks

 

[racerone]

That would be a Canadian built 1979 model.-----Install a new water pump impeller before your first fishing adventure.

 

[OFF SIDE]

Tks yes always a good idea. It is Canadian made . Doesn't the last two digits on the serial number indicate the year? The motor pulls over good with plugs removed. With the plugs installed its difficult to pull. Any suggestions as to why?
Does it just have you be run to loosen up . I'm taking the pull cord assembly off to see if the flywheel has a problem rotating. Tks

 

[racerone]

NO it does not mean the year !.

 

[OFF SIDE]

Can you please send the link? Ive looked up in a few locations can't find it. Also it looks like a 1979 uses muffs , this motor has to be put into a water tank run running

 

[racerone]

Do you still believe your motor is a 77 model ?----You can post pictures of your motor.

 

[Chris1956]

Remove the spark plugs, and turn the flywheel by hand. You should feel some compression in the crankcase, as she rotates. She should feel smooth, and except for the compression in the crankcase, she should turn over easily.

If not, drop the gearcase and repeat the test. Gearcases can bind up.

 

[racerone]

Many older Mercury models end with a 20 in the number.----Mercury started in 1939

 

[OFF SIDE]

Remove the spark plugs, and turn the flywheel by hand. You should feel some compression in the crankcase, as she rotates. She should feel smooth, and except for the compression in the crankcase, she should turn over easily.

If not, drop the gearcase and repeat the test. Gearcases can bind up.

Tks. Got to the flywheel, seems to turn with effort, good compression.
Reinstalled the pull cord assembly, can only pull about 20" of rope, very difficult . Its enough to get it running, but why?

 

[Chris1956]

If you get on a parts site, you may be able to tell the original length of the pull cord. 20" seems short. Maybe it broke and the PO retied the pull handle?

 

[racerone]

Most recoil ropes are 60" or 5' long.-----Installed a new impeller ?

 

[OFF SIDE]

Tks everyone, back at it. Replaced impeller, rebuilt fuel pump it was contaminated with ethanol crystals, cleaned carb .
I'm used to primers, this one has a choke.
When working the choke, I pull the knob out, the flap closes but opens when let go, springs back. Is starting this motor a two hand operation? Hold out the choke and pull the cord?

 

[racerone]

Repair / adjust the choke mechanism.

 

[airshot]

Neighbor has a 15hp motor and that is a tough pull for me, but was quite easy about 25 years back !! At 73 my 2.2 hp is all I want to pull nowadays, thats what they make electric start for...

 

[OFF SIDE]

The choke lever has indents on it. When working the choke ar these indents positions for the choke? Currently it just pushes in/out, but springs back to open when closed

 

[OFF SIDE]

Looks like the choke assembly has to be changed. Only problem part 72465 and 86874 are not available anymore. Any suggestions where to purchase, I'm in Ontario, Canada.

 

[racerone]

Where in Ontario?

 

[OFF SIDE]

Lake Simcoe area near Sutton.