Help Identifying Motor

[beerpilot]

Hello, I just bought a used 1970 Johnson 20HP outboard motor. I got it from a web purchase from a guy in Florida who rebuilds and resells used motors. I think the guy was honest but there's a few things that I don't understand.

In short my question for the forum is 'can you identify or confirm that it is the motor that was advertised'? Or, better yet what model is it?

The ID tag is no longer on the mounting bracket. The cover is from a 25HP Johnson Sea-Horse. Those are the confusing things.

The web site from the place I purchased has a good set of pictures. I hate to ask people to go look at another site but I couldn't do it any better than the seller did, http://www.smalloutboards.com/j2069.htm

I looked around for a manual, easy to find but it helps to know the model. It looks like the following 20HP models existed around 1970:
20R70
20RL70

25HP models around 1970 included:
25002
25003
25R70
25RL70

I don't understand the R, L or 70 identifications either,

Any help will be appreciated. I am a competent mechanic but don't know anything about boats or motors. I just picked up this motor and a 14 foot aluminum boat to put it on. The boat is rated for 18HP but those are really hard to find, I've been looking for months and found this 20HP. If it is really a 25HP than I might be worried about over powering the hull, at least I assume I should be worried.

Thanks,
Rick

 

[hidef]

Re: Help Identifying Motor

Based on the photos I think it is a 1969 or a 70. R = Rope L = Long Shaft. The 20 Horse was manufactured from 66 to 73. The cowls were interchangeable between the 20 to 35 depending on model.

 

[nwcove]

Re: Help Identifying Motor

have you looked around the power head for a freeze plug with the model/ serial number stamped on it?

 

[beerpilot]

Re: Help Identifying Motor

The power head does have what looks like a serial number, I assumed that was what it was, now I know. There is no sign of a model number though.

I got some details from the guy I bought it from, I'll include in case it's helpful to others:
----------------------------
The Johnson 18,20, and 25hp were all the same engine just carbureted differently. All parts were interchangeable. The person who traded it in to us mentioned it was a 20 hp. It may very well be a 25hp. The motor runs on pre-mix 50:1 gas to oil ratio.
---------------------------

So, I guess I'll start by getting a 20HP shop manual and if the carburetor doesn't match the book very well go get a 25HP manual.

Thanks for the responses.

 

[samo_ott]

Re: Help Identifying Motor

Bad paint job! They even painted the pull starter! It is true, the 18, 20 and 25hp are all the same 22 cubic inch block used from '57 to the mid 70's or so. Parts are pretty easy to find. But unless you can find the model # you will never know exactly what you have as they are hard to tell apart and I have a lot of them (10 or so). Someone more knowledgeable might be able to tell the subtle differences though, but not me!

And OMC 18's are pretty common. I'm surprised you cant find one. What part of the country are you in?

 

[samo_ott]

Re: Help Identifying Motor

Another thought I just had, how does the seller know it's a 20hp? I would ask him to prove it was and not an 18.

And welcome to the forum