Logo
FULL SITE MENU

Johnson 1972 20 hp (25 hp) no sparks

C

calle

Member
The motor is rated 20 hp but its most likely a derated 25 hp meant for the european market. There is no spark on either spark plug, what would be possible faults. Any advice appreciated, thanks.
 
Last edited:
calle said:
The motor is rated 20 hp but its most likely a derated 25 hp meant for the european market. There is no spark on either spark plug, what would be possible faults. Any advice appreciated, thanks.
Click to expand...

You dont tell us much in the way of history. New to you motor not working or a hitherto good runner just packed up or what ?

How are you checking for sparks?

Coils, points, condensers, bad plugs even but with no spark on either plug Id start by checking the stop button.
 
Last edited:
Pull the flywheel.----You will find 2 cracked coils or a replacement set already.-----Post a picture of the coils.---If coils have been replaced , likely a cleaning of points is all it needs.
 
This should be a fun fix. New coils, points and condensers. Will cost you all of 50 bucks. Good for 20 years or more.
 
calle said:
The motor is rated 20 hp but its most likely a derated 25 hp meant for the european market. There is no spark on either spark plug, what would be possible faults. Any advice appreciated, thanks.
Click to expand...

The 20hp was also sold in USA. There are significant internal differences between the 20 and 25.
 
Thanks for your advice guys. I was offered this motor hence the enquiry. After a more thorough check I noticed the 20 was sold in the states aswell, thanks.
would changing points or coils also mean readjustment of ignition timing is needed?
 
Last edited:
The only "timing" is the time that the breaker points open. That is determined by the points gap (0.020"). There is a timing fixture to get that more precise, but not absolutely necessary.
 
Back
Top