Compression

Sebago13

Seaman Apprentice
Joined
Aug 20, 2019
Messages
33
Would anyone know what the compression should be for a 1971 20hp Johnson. 20R71S
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,051
There are many , many of these motors around that have hardly been used over the years.------Some spend much time in proper storage.----Used for just a few hrs every year.----If you just bought it remove the flywheel to check the coils.-----Bonus if you finfd them cracked.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
There are many , many of these motors around that have hardly been used over the years.------Some spend much time in proper storage.----Used for just a few hrs every year.----If you just bought it remove the flywheel to check the coils.-----Bonus if you finfd them cracked.

Not sure why you would want them cracked, didnt think they were like walnuts but am here to learn too
 

lindy46

Captain
Joined
Nov 27, 2008
Messages
3,886
Cracked means original and it probably hasn't been used for years and is most likely a low hours motor.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,051
Exactly----If coils are cracked then it likely has not been used for many years.-----Most likely then a low hrs motor.-----I see that all the time !!-----I have many new coils on hand here as it is a very , very common thing.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,924
The comp readings: as long as they are even or real close.
Different gauges read differently.
Harbor Freight sells JUNK and they don't give the right readings.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Ahh interesting, "cracked" in that sense seems to be an exclusive North Americanism
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
I see a lot of German, Japanese, and especially British Engineering that is Cracked
 
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