1970's mercury 650 four

[nmTampafl77]

So I just bought a 1970's.... Not sure the exact year Mercury 650 Four cylinder. And Im just wondering if these are decent motors. I am using it to power a 15 ft tri-hull. The compression on it is 120 across the board. I am not very familiar with Mercury motors

 

[fastjeff]

Solid motor that doesn't like to troll, so don't do that and you'll be fine.

Jeff

 

[racerone]

1971 was the last year for the 4 cylinder 65 HP.------------Sure it will troll if in good condition.

 

[nmTampafl77]

Someone from another forum told me they were garbage motor's.... and thats why they made them for several years and stopped.

 

[racerone]

As always money plays a big part.---------------Mercury sales numbers were reduced by a " hot selling " 3 cylinder OMC product.-------------As a manufacturer you have to respond when sales go down.---That was the 3 cylinder 65 HP in 72.----There was nothing wrong with the 4 cylinder 65 HP Mercury and I would rather own one of those than that 3 cylinder Mercury.-----Money screams !!

 

[nmTampafl77]

As always money plays a big part.---------------Mercury sales numbers were reduced by a " hot selling " 3 cylinder OMC product.-------------As a manufacturer you have to respond when sales go down.---That was the 3 cylinder 65 HP in 72.----There was nothing wrong with the 4 cylinder 65 HP Mercury and I would rather own one of those than that 3 cylinder Mercury.-----Money screams !!

That makes alot of sense.

 

[fastjeff]

The logging guys in the northwest LOVED that motor since they ran forever. The fishermen who tried to troll with them did not since they scuffed pistons after extended trolling sessions (since they ran too cold. The use of a thermostat would have cured that.) '

The motor was NOT replaced; it was updated with the new power dome piston design, becoming 2/3 rds of a big six--and there was NOTHING wrong with them!

Jeff

 

[faztbullet]

Hate to disagree with ya but the pistons where never updated in this motor to the inline 6 pistons, still uses the flat dome crossflow.(2-15/16) They did not troll good due to it being a long stroke engine and do not like excessive rpm as they will disconnect rod from crank.

 

[fastjeff]

Note that I said "inline 6" not V-6.

Jeff

 

[faztbullet]

Note that I said "inline 6" not V-6.

I didnt post V-6 ...This engines piston dome is more line a OMC v-4 dome, and never was updated to use the inline 6 piston as dome is different, The early 950,1000,1100,1250 and 1350 also use this same piston design.. see below..