1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

[Watt]

I have a 1962 Johnson seahorse rds-24. Bought her for $300 online. I ran it last summer with fairly good results. The major problem i had the whole season was trying to troll the motor! It would start to sputter and gradually it would die if didn't give it any throttle. Seams like i would have to run at WOT for a bit to "clear the carb" before returning back to a lower rpm. I adjusted the low speed quite a few times and found its happy spot, but still had the low rpm sputter. I Purchased a carb kit, fuel pump kit, points, and condensers from iboats which should be here in a few weeks. I have a feeling it's the carb but i figured I might as well replace all of these things while I'm down there haha.
If anybody has any advice or ideas that would be great. I plan on doing a complete overhaul of the motor in April while I can't fish. Might start earlier than that considering the amount of snow we have received here in Saskatchewan. It has been tough getting onto the ice lately!

 

[kfa4303]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

Hi Watt. Welcome to iboats. Cool old motor you've got there. You'll definitely want to give the carb a thorough cleaning and rebuild, which should imporve the low speed idle greatly. The new points and condensers should make a nice strong spark once you've got them installed as well. I sould suggest you read through the link(s) below a few times while you wait for your parts to arrive. Assuming the compression is ok on the motor, all the rest is pretty cheap and easy to fix using a few wrenches and a flathead screwdriver. Holler if you have any questions.


Reviving a Vintage Big Twin - Part 1

http://forums.iboats.com/engine-fre...sorted-carb-variations-joe-reeves-167352.html

3 HP Evinrude Lightwin Ignition System Tune-Up 1952-1967 (great ignition rebuild link)

5.5 HP Evinrude Johnson 1954-1954 Carburetor Tune-Up Procedure (great carb rebuild link)

Vintage Evinrude Johnson Outboard Parts & Diagrams - Catalog 378826

 

[Watt]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

Thanks for the response. I am going to post a few picture here of my progress here in the last two days. One question i do have is that when i took a look at the diaphragm for my fuel pump it was very thin and loose. I was looking at pictures of new ones and it appears to me that mine is extremely worn out. (could this be the reason for significant throttle to engine response delay?) When in a trolling speed it would really take a while to start accelerating once the throttle was opened up. As for Cleaning the carb, i stripped it down and threw it in an old pot a boiled it with lemon juice. (heard this works great) Seems like it did a pretty good job. I used carb cleaner and canned air to make sure every passageway was clean. Now i just have to wait for the parts to show up before i finish the rebuild for the carb and the fuel pump. As for the condensers and points i need to get my hands on a gear puller.(part source should have this.)
Thanks for the feedback and here are some pictures so everyone can see whats going on.

 

[F_R]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

For one thing, that has the infamous water heated automatic choke. Even when brand new, they often didn't work worth a hoot. That could be part of your loading up problem. Most people operate them manually. Just open the door and flip it to choke-on position to start the motor, then flip it to choke off position.

If you insist on using it in automatic position, at least be sure the thermostat int the head is working. But irregardless of how you operate the choke, the thermostat controls the engine temperature (and somewhat the under hood temp also). That affects idle quality.

Spark/carb throttle synchronization is extremely important. You are fighting a losing battle if that isn't correct.

Your thinking is correct on the ignition system. Most "carburetor" problems actually are ignition problems. Dirty/oily points are almost a certainty and cracked coils are common. Get it all right and it will treat you right.

Probably not a factor, but a possibility is clogged crankcase drain valves. Their function is to prevent loading up at idle.

Yes, a pin hole in the fuel pump diaphragm will make it run rich on one cylinder.

Last, but not least, is it leaking exhaust smoke into the hood? Does it run better with the door open? Could be the rubber donut between the inner and outed exhaust housings, but also very common is the seal on top of the water pump housing.

Lots of diagnosing to do, and as you can see, it is not as simple as just saying clean the carburetor.

 

[Redwing4900]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

My humble opinion I think once you do the carb rebuild you will be good. I have the same motor like yours, but have yet to use my 1962 (RDSL-24). I plan to use her this spring. Did you find that your battery power ran down when you used the motor? I also have the electric shift motor (RKL-25D, 1963) that needs the generator, and was wondering why the mechanical shift didn't have the generator with it. Until I saw the pictures of yours I was sure I would need it, but now, not so much. You do have the mount for the generator or what could be used as such, maybe its not needed though. Thanks for the pictures, I was working on mine this afternoon, and was delighted and encouraged to see a picture of what I was looking and cussing at today. Encouraged, because I thought mine was the last of its kind!

 

[Watt]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

I tried it in the auto choke position once, didn't move an inch. Its just decoration on the carb. As for Spark/carb throttle synchronization i haven't been able to find much on this other than a manual i found.(johnson evinrude 1956-1970-1-5-40hp outboard repair manual improved)I am not an expert and found it pretty confusing seeing as all the pics in there are from the 60`s. If anyone has any material to help me figure out the synchronization that would be awesome. Regards to the exhaust leaking into the hood i don`t think i had that problem last year. It ran no different with the hatch open or closed. (seamed to be open always because i was constantly fighting with needle adjustment lol. I know with this carb i seat the needle fully closed, open 1 1/2 turns, turn 1/8 at a time closed until i hear a sputter and crank it a 1/4 turn open. I am Looking forward to pulling the flywheel next weekend so i can get a good look at the ignition.

Reply to Redwing4900
No i did not find that my battery was draining while the motor is running. I wonder if you could hook up a voltmeter to it and source out where its drawing from. I'm amazed at the response i have gotten on this forum, its great. I ran that motor all last year on a deep cycle battery and it still had plenty of cranking amps at the end of the year. (thats with lots of stalls lol) Gonna throw it on a maintainer to top it off to ring in the new year.

 

[Willyclay]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

If anyone has any material to help me figure out the synchronization that would be awesome.

This Johnson factory manual is the best I have found online: Boatinfo - 1922-1964 Johnson Service Manual

Your description of the low speed/idle problems reminds me of my RDSL-21. It was seized when I got it and, after a complete teardown and rebuild, it started and ran on the first crank. However, it would not idle. Finally, I found some hard crud in the low-speed needle valve passage that somehow had survived three previous cleanings. It required a pick to remove. Ran great from that point on. Good luck with that great old motor. The old RD series motors will not die, you have to murder them!

EDIT: Link & sync procedures are on manual page 156.

 

[F_R]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

The battery on a manual shift motor is used only for starting. So, it will go a long time without re-charging, and a generator kit was sold as an accessory kit. All bets are off if you have a bunch of other stuff connected to it.

A generator is necessary on an electric shift motor because it requires power to keep it in gear. That is why they came from the factory with a gen.

 

[Watt]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

Sounds like those electromatics are bad news.

 

[kfa4303]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

yeah, the electromatic models can be a bit of a nightmare. you have to have a battery, they're complex and parts aren't cheap, assuming you can find them. although, they are very smooth....when they work. I'm a big fan of KISS, so I don't mind a manual gear change. It's a small price to pay for increased reliability and decreases expense.

 

[Watt]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

This Johnson factory manual is the best I have found online: Boatinfo - 1922-1964 Johnson Service Manual

Your description of the low speed/idle problems reminds me of my RDSL-21. It was seized when I got it and, after a complete teardown and rebuild, it started and ran on the first crank. However, it would not idle. Finally, I found some hard crud in the low-speed needle valve passage that somehow had survived three previous cleanings. It required a pick to remove. Ran great from that point on. Good luck with that great old motor. The old RD series motors will not die, you have to murder them!

EDIT: Link & sync procedures are on manual page 156.

After reading this manual i completely understand how to sync my motor. Thanks for the post.

 

[Willyclay]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

Glad to help. Post updates as you proceed so we can share in your experiences. Good luck!

 

[Watt]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

Will do. Might not get a chance this weekend. hopefully i will next weekend.

 

[nwcove]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

i notice mention of a "gear puller" in an earlier post......dont use a gear puller , a harmonic balancer puller is the tool to remove the flywheel.

 

[Watt]

Re: 1962 Johnson Seahorse RDS-24 runs poor at low rpm while in gear.

My bad thats what i meant. Google imaged a harmonic balancer puller and that is what I thought it was. Thanks