1961 johnson fd-15 18hp

Riverrat47274

Seaman Apprentice
Joined
Sep 6, 2013
Messages
41
Hello all!I just recently bought a 1961 Johnson 18hp motor and it is lacking power.runs about like a 9.9 or so.its on a 15' bass catcher.motor starts right up,idles good but top speed is just not there.i dont notice and bogging down or anything like that.just put new plugs in it today.if anybody
Can give me some things to check out what might be causeing this i would appretiate it.thanks!
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
Re: 1961 johnson fd-15 18hp

likely it is running on one cylinder.----It has a dual ignition system and one of the 2 may not be working properly.-----The only acceptable test here is as follows.----Make the ignition system jump a gap of 1/4" or more.---That is the proper test.---Laying the plugs on the block and seeing spark is " fools gold " and useless information.
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: 1961 johnson fd-15 18hp

Check the compression on it.
 

kfa4303

Banned
Joined
Sep 17, 2010
Messages
6,094
Re: 1961 johnson fd-15 18hp

Hi rat. I have a '66 20hp, which is virtually identical to your motor and it pushes my 14' Tinny along nicely at around 20mph. I suspect you may only be running on one cylinder too. Thankfully, the compression looks good, so I would confirm that you are getting a nice strong spark capable of jumping a 1/4" gap. You want to use Champion J4C or J6C plugs. Here are some handy links.

3 HP Evinrude Lightwin Ignition System Tune-Up 1952-1967

Maintaining Johnson E & FD Serie
 
Top