runs rough 58 JohnsonRSD20

[rebars1]

1958 Johnson RSD20: I've replaced the plugs, points, checked timing, rebuilt fuel pump, & carb. The motor ran good for a little while, but still had a slight miss fire about every 5 seconds or so. Now I'm seeing more smoke than before and it seems slow to accelerate when I push the trottle up (seems to bog down)<br /><br />Any ideas? Can the cut out switch cause the miss fire?

 

[rolmops]

Re: runs rough 58 JohnsonRSD20

You will have to tweek the idle needle valve and do the same for the high speed one.It sounds like they may be a tat to lean.

 

[CFronzek]

Re: runs rough 58 JohnsonRSD20

This motor is closing in on it's 50th birthday! Old age can bring on a lot of nickle and dime problems. <br />You've gone over what's on the outside. How good is the inside. A compression check would identify how much wear and tear is on the engine. Age could be effecting the insulation on any of the wires. Your carb job could have loosened up some dirt that didn't get into critical passages until after you put the motor back into operation. There could be an accumulation of dirt in a fuel line, etc. <br />A motor this old is kind of a geriatric case. It can suffer from problems you'd never see on a newer motor. To keep it putting along you're going to have to put up with a lot of small, age related problems.<br /><br />Charlie <br /><br />"1940 Johnson HD15"

 

[CATransplant]

Re: runs rough 58 JohnsonRSD20

Hi!<br /><br />We have the same outboard. Mine runs as smooth as silk, and yours should, too. These are excellent outboards and, when properly tuned, run very smoothly.<br /><br />So, the goal is to get yours running that way, too.<br /><br />You say it misses every 5 seconds or so. Do you mean it actually cuts out, then picks up again? If so, that's not a miss...it's an ignition problem.<br /><br />Yes, your kill switch wires could be causing this. As a test, disconnect both of them, and insulate the ends. Two small black wires come down from under the flywheel. One goes to the vacuum cutoff switch on the throttle side of the engine. The other goes to the wiring harness plug on the side of the engine. <br /><br />Take the first one off the vacuum cutoff switch, then tape the connector. The second one has a knife connector in the wire before it gets to the harness. Disconnect this and tape that end, too.<br /><br />Now, try the outboard out. If this cures the miss, then you'll have to track down the problem, which will probably be somewhere in the external wiring harness to the control box and ignition switch.<br /><br />If not, then it'll be time to check under the flywheel. Your coils may be old and failing. If so, new ones aren't all that expensive. Points can be dirty, but that normally doesn't cause a repeated problem that occurs like you describe.<br /><br />If the plug wires or kill switch wires are misrouted, they can rub on the flywheel and short out sometimes. A physical examination will disclose that.<br /><br />Bottom line is that your old 35hp Johnson should run as smoothly today as it ever did. Ignore those who tell you otherwise.<br /><br />Mine will idle down to a bare tickover and run my boat less than 2 mph. It will also instantly speed up to 4500 rpm and push my little boat at 28 mph.<br /><br />So, describe your problem in as detailed a way as possible and we'll help guide you to a fix.

 

[BoatBuoy]

Re: runs rough 58 JohnsonRSD20

And besides that, geriatric motors are much easier to work.

 

[CATransplant]

Re: runs rough 58 JohnsonRSD20

The excess smoke and poor acceleration may be a carburetion problem. Rebuild kits for this carburetor are available from johnnyrude dealers and from Sierra Marine Parts, through any NAPA dealer or here on iboats or other online marine parts dealers.<br /><br />You should be running this motor on a 24:1 fuelil mixture (one quart of TC-W3 oil to 6 gallons of regular gas). It'll smoke some.<br /><br />If you haven't already done so, do change the water pump impeller, also available from Sierra marine parts. If you can't find the part numbers, just ask, and I'll look them up for you.<br /><br />Spark plugs should be Champion J4C, gapped at .030". Point gap is .020". <br /><br />Give us details about your problems, again, and we'll get you running smoothly.

 

[almost retired again]

Re: runs rough 58 JohnsonRSD20

Hi Rebars1;<br />This thread seems to have a lot of (at Least 2)sailors on it,so I just had to chime in seeing as how I spent 20 years in the submarine service. After I retired I spent 2 years in a marine Tech school, then worked as a mechanic for 17 then taught a marine service tech school for 5. I am retired now.<br />What I wanted to say about your problem though is to listen to what CR Transplant said; hi is giving out good information.<br />I have in my notes from an early OMC school that says that any engine that Johnson/Evinrude made in the past will run on a 50:1 if it has been decarbed first. I have used this advice on older engines with no problems. Ithink the reason for this is that the newer 2cycle oils lubricate better and stay in suspension better than the old 30 weight oils of the past. Anyway good luck and keep us informed

 

[rebars1]

Re: runs rough 58 JohnsonRSD20

Hey, you guys have gotten me this far with info from the past and I actually had the boat in the water last week (after 15 years!) and I know I'm getting close to getting this engine back on track. <br /><br />I had it on 50:1 until about two weeks ago when I was informed by CATransplant (and confirmed in my factory manual) that it should be on 24:1. Just prior to that, I had had it tweaked by a mechanic who replaced the flywheel (cracked) and adjusted the points, and carb., but he was using 50:1. I already have the rest of the electronics, so I'll replace those as well. The mechanic got it running smoothly except for the occassional skip in the firing, which he suspected might be from the vacuum cutoff, but wanted me to try it out first. <br /><br />I have already replaced the waterpump and thermostat.<br /><br />I'll do a compression test and check the cutoff switch per CAtransplant's procedure and report back. <br /><br />Thanks again.

 

[rebars1]

Re: runs rough 58 JohnsonRSD20

I just warmed it up and did a compression test. Both cylinders tested at 150 psi. The bottom plug was clean and looked (and is) brand new. The top plug was black and oily, but not fouled. I think it may not be firing all the time, or maybe not at all?<br /><br />CATransplant: The motor does not back fire, but, rather, skips a beat, jerks, and keeps running.<br /><br />There are three wires coming off the cutout switch. The third one connects to where the trottle shaft enters the motor housing, then a tan wire goes from there to the harness connection.

 

[krb113]

Re: runs rough 58 JohnsonRSD20

ARA, I also have been told the same about 50:1 on any because the newer oil is better by my uncle that worked on outboards in New Mexico for about 40 yrs. I have run my '58 18 hp this way for 4-5 yrs. with no problems. My brother runs his '57 35 hp John. Javelin the same now for 6-7 yrs.

 

[rebars1]

Re: runs rough 58 JohnsonRSD20

I did the cutout switch test but the skipping problem did not change.

 

[CATransplant]

Re: runs rough 58 JohnsonRSD20

OK, then it's probably not the kill circuit. An intermittent miss like that can be hard to diagnose.<br /><br />Are the coils in that outboard the originals? If so, I'd replace them, especially if they look broken down. The new ones are cheap enough, and will outlast the rest of the outboard.<br /><br />I'd also check the plug wires for proper connection in the coils, especially if they've already been replaced.<br /><br />This could still also be a problem with the kill wires. If they're making contact with the flywheel anywhere, or the insulation is worn or rotting, one or both could be grounding intermittently, which will cause the kind of miss you're experiencing.<br /><br />I would still run that outboard on 24:1, despite the reports of some running them on 50:1. It's your choice.

 

[rebars1]

Re: runs rough 58 JohnsonRSD20

Thanls CATransplant. The coils were replaced about 15 years ago, but new used. The spark plug wires are original. I'll replace both and report back.

 

[CATransplant]

Re: runs rough 58 JohnsonRSD20

Good idea on those coils. The new ones are much better. New wires are also a good idea. Just be sure that they're fully seated and that they have real wire cores. You don't want to be pulling the flywheel more often than necessary. While it's off check the point gap again, just to make sure it's .020" at its widest point.

 

[rebars1]

Re: runs rough 58 JohnsonRSD20

Update: I replaced the coils, points, condensors, & spark plug wires and tried it out. It ran OK at first at slow speed and medium. I push it full throttle for a shor wile then backed it off because it started running rough. Then one cylinder shut down, but would kick in once in awhile as I headed back to the marina. Back on land, I tried pulling off one spark plug wire at a time. There was no change when I pulled the bottom one, but the motor stopped running when I pulled off the top one. I checked the sparks. The top cylinder was strong and blue, firing every time. The bottom one was orange/yellow and did not always fire. Maybe the spark is not hot enough to burn the fuel? <br /><br />Any ideas to fix the spark?

 

[Chinewalker]

Re: runs rough 58 JohnsonRSD20

Could be dirty points, or possibly a misadjusted coil. The laminates of the coils must be BANG-ON even with the machined outer rim of the mag plate. Could be a loose mag plate, too, causing the point gap to bounce around a bit (see below). Could also be a partially blown head gasket, although your compression numbers appear to be good and even. Any evidence of water on the plugs?<br /><br />Your next step after eliminating the above suggestions might be to swap magneto components one at a time and see if the issue follows one. It's possible you got a bum coil or condenser.<br /><br />Are the points gapped at .020" with the rider of the point rocker aligned with the crankshaft keyway? Can you move the mag plate back and forth at all, effectively changing the point gap? Is the cam oiler present and oiled?<br /><br />It sounds to me like this is either going to be a "forehead slapper" (Doh!!) issue, or you may have gotten a defective part somewhere along the way....<br /><br />- Scott