1970 Johnson 20HP

[66fordguy]

Hey guys I am new to the forum and found it while searching for information on an outboard motor.

I purchased a 20HP 1970 Johnson 2 stroke with electric start. The guy I bought it from told me it needs carb cleaning and tuning and needs the impeller replaced. Last night I built a stand for it and I have a 55 Gallon drum waiting to be filled up.

I managed to get it running last night, but had to spray ether to keep it running so it is not getting fuel, but spark is there.

I am looking for an owners manual/repair guide if they exist, does anybody know where I can find one? I have no idea where the impeller is and where I would have to start tearing it down. I will probably take the spark plugs out and clean them up, or replace them if they are really bad.

Also where would I find those parts online?

Have some experience with carburetors since I own a 66 mustang with a 4 barrel 289.

Thanks for any help.

 

[05blastsrt4]

Re: 1970 Johnson 20HP

Hey guys I am new to the forum and found it while searching for information on an outboard motor.

I purchased a 20HP 1970 Johnson 2 stroke with electric start. The guy I bought it from told me it needs carb cleaning and tuning and needs the impeller replaced. Last night I built a stand for it and I have a 55 Gallon drum waiting to be filled up.

I managed to get it running last night, but had to spray ether to keep it running so it is not getting fuel, but spark is there.

I am looking for an owners manual/repair guide if they exist, does anybody know where I can find one? I have no idea where the impeller is and where I would have to start tearing it down. I will probably take the spark plugs out and clean them up, or replace them if they are really bad.

Also where would I find those parts online?

Have some experience with carburetors since I own a 66 mustang with a 4 barrel 289.

Thanks for any help.

First, never run an outboard with starting fluid your rings, pistons, and walls will thank you.

boats.net has some oem parts.

as for your impeller you will have to remove your lower unit, it should be right on top.

 

[tbfosback]

Re: 1970 Johnson 20HP

First off I totally agree with 05blastsrt4^^^^^^^ Never use starting fluid in a 2 stroke..
Many parts are avail. right here on Iboats. The sponsors of this site... Just give us a model number and many people can help you out...

 

[tbfosback]

Re: 1970 Johnson 20HP

This should get you started
Manual Many local libraries have them as well.
http://www.iboats.com/Johnson-Evinr...5913236--**********.614383349--view_id.214854
Impeller
http://www.iboats.com/mall/partfind...gd_poid=110866&gd_row=10&**********=014318664
carb kit with float.
http://www.iboats.com/mall/partfind...gd_poid=109344&gd_row=31&**********=325857940
This is just assuming it is a 1970 20hp.

 

[66fordguy]

Re: 1970 Johnson 20HP

it is a 20r-70e with electric start and 2 stroke. I can give the serial if necessary, but I would imagine the model number provides all required information?

I never knew about the starter fluid! Thanks. Does anybody have a reason why it is not recommended? Because it does not have oil mix with it?

I just came in from attempting to remove the carburetor. One of the two nuts is behind the starter, is there a simple way to move the starter out of the way without tearing everything apart?

I will probably end up ordering a service manual when I purchase the parts for it.

Where is the fuel pump located? I am assuming it is a mechanical pump and runs off the motor?

Sorry for the green questions but I have never owned a boat motor let alone worked on one, and I love working on anything carbureted

 

[66fordguy]

Re: 1970 Johnson 20HP

Some information about the motor: Sat for many years by an old lady and purchased by the previous owner (honest man who sells custom built fishing rods and reels) and he ran it for a few years, but has few hours worth of time on the water, so all the original blue paint is still on there, in fact any screws I take off removes that factory paint. Compression is very good just by hearing it, and the spark is great. Does appear to have a fuel issue but will not further investigate until I remove the carb and clean it up.

 

[CatfishMN]

Re: 1970 Johnson 20HP

I may have missed something, but in you original post you said you were waiting to fill up the drum. Did you run the motor with no water circulating? This should never be done.

 

[66fordguy]

Re: 1970 Johnson 20HP

For 5 seconds at maximum. I will fill up the drum now before I give it the maiden test. I just cleaned and rebuilt the carb, cleaned and rebuilt pump, and cleaned up the plugs.

Is there a way to adjust the needle for the speed? Is it the idle speed? I took it out cleaned it up turned it all the way (without bending it at the end) and backed it off 1.5 turns. If anyone knows anything about this please let me know.

Thank you for the help so far everybody, I am having fun working on this motor!

 

[66fordguy]

Re: 1970 Johnson 20HP

Well she fired right up and after adjusting the air/fuel she was purring oh so smoothly.

Apart from fuel line leaks there is a leak above the lower unit, it leaked oil all inside the drum. What could it be? There is like an outlet that it is slowly dribbling out of.

 

[tbfosback]

Re: 1970 Johnson 20HP

Did it pump good water? Many of the questions you have may be in the FAQ section here. Many of the pros on here I have found invaluable.
http://forums.iboats.com/showthread.php?t=207285
http://forums.iboats.com/showthread.php?t=167352
Wish you many happy years with your motor.

 

[CatfishMN]

Re: 1970 Johnson 20HP

It is normal to have oil in the test drum. It is unburnt oil/gas mix accumulating there. There will be some of this exhaust mixture that will weep from places that make you think it is the lower unit. You'll have to drain the lower unit and look at the oil to determine if it has a leak. If it looks milky, you have water intrusion. Give the fluid that you think is leaking a smell test. If it smells like gas/oil, it is not from the lower unit, but exhaust.

 

[66fordguy]

Re: 1970 Johnson 20HP

Yeah it pumped water great. In fact we agreed that the impeller is good. I think we will end up changing the oil in the lower unit and replacing the seal and seeing how it does.

One more questions, if you guys don't mind helping me out with, is we can't get it to go into gear? There is no change in the way it is when we put it gear. I am guessing the gear selector is the shifter on the side and neutral is in the middle? If so moving it left or right does not do anything. The water moves like crazy but my uncle said that it was just the exhaust because it moves faster as you raise the rpms.

 

[lindy46]

Re: 1970 Johnson 20HP

If you put it in gear in a test tank, it will throw lots of water out of the tank. If it doesn't do that, check the shift rod linkage - remove the oval plate on the side of the leg and see if both shift rod ends are properly attached to the coupler. Two bolts hold the upper and lower shift rods in the coupler.

 

[66fordguy]

Re: 1970 Johnson 20HP

Great! Thanks for that I will check it out at some point this weekend and post results.

Looking forward to this john boat being able to go farther than the troller motor will take us.

Does anybody think this motor is too big for a 10 ft john? The recommendations on the boat are 10hp max, but a new 6-8hp weighs the same as this 20hp. I am thinking as long as we drive it easy without pushing to much rpms from a stand still it will be ok.

 

[tbfosback]

Re: 1970 Johnson 20HP

I don't know if I would use that motor on that boat if it was me. If the hull rating is only 10hp max it is probably a pretty light weight transom. I am worried that your hull may flex under load. But if you do run it watch out for law enforcement. They really don't have too much humor anymore about overpowered boats.... Just my $0.02...