'54 evinrude 25hp troubles

[jbjennings]

I have had problems setting the float and getting spark on the bottom cylinder of this thing. I seem to have the float set and have finally succeeded in getting spark on the bottom cylinder. Here's how--I disconnected a single wire that goes from the points/coil/condenser connection to a device on the front of the motor up and to the right of the carb that has one vaccuum line going to it. I have from the most reliable source that it helps the motor rev down smoother by killing power to the spark plug on one cylinder. Since the wire attached to this device goes to the bottom coil/points connection, I assume this is the one it kills. Now, I've checked the connection on the device with a meter to see if it is grounded and it is not. I believe under enough vaccuum it will complete the circuit and ground the wire and short the ignition to the bottom cylinder. My question is, why is it shorting the bottom cylinder's coil if the connection on the device is not grounded. I couldn't find any bad insulation on the wire connecting the two.
Question 2-- I can't seem to get the motor to idle down smooth. I have cleaned the carb. My gasket on the high speed nozzle between the 2 carb halves isn't too sporty. When I turn the throttle down a little it will idle down for a few seconds and then die with a hard cough. If I richen it up with the slow speed knob it will not idle down without dying quicker. It will fast idle with the high speed valve totally closed.
ALso, I feel very little vaccuum on the hose going from the intake manifold to the over-revving control device. Should I feel quite a bit?
Sorry for all the questions but this thing is really eating me up.
JBJ

 

[jwh114]

Re: '54 evinrude 25hp troubles

Are the coils good?

 

[samo_ott]

Re: '54 evinrude 25hp troubles

The vacuum switch is meant to do what you said. It prevents a run away situation. In the event of a run away situation, the high vacuum will close the switch and short out the coil on the bottom plug and thus slow the engine down. You only see it on the big and bigger twins (not sure why only on the bigger engines though - a good question to pose). Anyway, in a runaway situation even closing the throttle will not stop it and the engine could self destruct, thus it shuts down one cylinder.

As for the carb. They take fine adjusting. There's a knack to it I'm still trying to figure out also. One of these years... All I can suggest is to make sure it's real clean...

At least your working on engines... Still many feet of snow here but it is getting warmer...

 

[tmcalavy]

Re: '54 evinrude 25hp troubles

Hey JB, wish I had a solution for you...I just recently gave up on a 58 Johnson 35 hp super sea horse twin that I've been playing with for the same reason. It runs good at speed, but won't idle down and coughs and dies in the low end. When I was inspecting the carb, I noticed the packing for both high and low speed needles was coming apart. I suspect I've got some small crud in there somewhere that interferes with the slow-speed idle circuit. Don't think the over-rev is causing your problem, it's only there to kick-in a shut down when the revs are way over spec in the top end. If you sort it out, let me know...maybe I'll be ready to tackle the Johnson again by that time. Take a day or so off and go fishin, then come back to it.

 

[BoatBuoy]

Re: '54 evinrude 25hp troubles

Here's the description from OMC of what that vacuum cut-out switch does:

"Conditions under which the cut-out functions to limit maximum idling speed are as follows: If when running at fast idle in neutral (2000 RPM or more), the throttle is suddenly closed, a surge or sudden increase in manifold suction is introduced. Under influence of abnormal manifold suction in this instance, the fuel vapor mixture is not consistently ignited but will tend towards firing erratically (as combustible mixtures form*) to result in irregular but excessively ?strong? power impulses to sharply increase motor RPM?s even though the throttle is closed ? Resultant high motor speed (RPM?s) cannot under the circumstances be otherwise reduced or controlled by simply closing the throttle and since no manually operated ground switch is employed, other means are required ? thus, the automatic cut-out..."

 

[jbjennings]

Re: '54 evinrude 25hp troubles

Thanks guys, now I'm really depressed.....If Ya'll can't get it idling down smooth with all your experience, it feels hopeless for me. But I am a stubborn person and if I have to try everything I will fix that rascal.
Just in case this will help, here's some info. Brand new coils by the way (I don't play on coils!) and condensers, cleaned/resurfaced pts.

Compression on top= 103lbs.
bottom= 106lbs.

Serial number = 25916-09962 '54 model, right??

Also, here's a pic of a tiny chunk missing from the butterfly shaft area. I believe there is still plenty of material there to make a good seal. What do you think?
Can any of you experts pose any possibilities on modifying the carb to get a better mixture on idle? I know this is stupid, but how about the boyesen reeds thing? Any chance?
I will try to clean the darn thing better but it is pretty dang clean.
Thanks again,
JBJ

 

[kbait]

Re: '54 evinrude 25hp troubles

Make sure gasket between the carb halves is sealing, and make sure needle jet packing is sealing. I've had 'em run just as you describe. I sometimes use 2 different size o-rings and grease/needle seat and it always works. g'luck,kirby

 

[wbeaton]

Re: '54 evinrude 25hp troubles

25916 is a 1954 Evinrude Big Twin Electric 25 hp. I'll send you the proper parts manual. I have the same motor all tuned up, but never run.

Your compression is fine. My old 1953 25 hp had about the same and ran great. Mine was hard to adjust, as well. It was very finicky. After a few outings I had it running WOT great and idling fine. However, low idle was tough until it was warm. It never idled as low as I would have liked, however it was low enough to troll so what am I complaining about.

I found my GPS helpful when trying to find the best opperating settings. Get the WOT setting worked out then tweak the idle. You will be in the boat for a while going fast then slow...fast then slow, but I doubt you will mind!

Its just going to take time, JBJ. And lots of patience. Make sure all the seals are good.

Good luck. I look forward to seeing some photos when you're done.

Also, I can't see what's wrong in your photo. Is it missing a piece behind the spring? I don't think it'll cause you any trouble.

 

[jbjennings]

Re: '54 evinrude 25hp troubles

thanks Wayne and KBait,
I'll try what you mentioned....
Wayne, why did you tune your '54 but not run it? Weather??
Run it and give me a report/ video! Hurry up, I don't have all day! Does your's have e-start? I'm going to try to get it for mine if I can get it running like I want. It does idle well enough to use, but not perfect. I want it to run like my 10's, 15's, and 18's! Am I expecting the impossible?

By the way KBait,
I see you haven't made a lot of posts here. Are you new? If so, I hope you'll stick around because I need a lot of help on my oldies! I really appreciate your advise.

Thanks again,
JBJ

 

[wbeaton]

Re: '54 evinrude 25hp troubles

I bought the 1954 thinking I'd put it on a small runabout someday. Since I don't yet have a runabout I didn't want to get the motor running and then put it away on the back rack for 2, 3 or however many years until I find one.

Mine has e-start. Yours should too. Unless it was removed. Does your cowl not say Big Twin Electric across the front and have a big lightening bolt? I just saw a 1950's e-start kit for sale for $80 locally. I considered buying it just to have the parts. Don't remember if it was for an 18 hp or a Big Twin, but it was Evinrude blue.

I figure that the Big Twins were not really meant for extended trolling or slow speeds so you can't expect them to run as nicely at idle as the smaller motors. Even my 1988 30 hp doesn't idle and troll as well as my 50's 7.5-15 hp motors.

 

[jbjennings]

Re: '54 evinrude 25hp troubles

Wayne,
I did a little tinkering on it and got it to run with the vacuum cut-off switch on and repacked the highspeed valve. It runs and fast idles but I can't get it anywhere close to idling at the 2 marks on the throttle cam. The throttle grip is pointing to fast when it is idling, I can't even get it close to "start" before it dies. Sounds like it leans out after a few seconds and then lean sneezes and dies. I have a new main gasket for it on the way along with a new float but I don't think they'll change anything. At least it is running and usable. The lower unit was full of water but I refilled it with oil and I'm going to take ti for a short ride tomorrow to see if I can make some adjustments. Here's a running pic of the rascal. I repainted it but may repaint again because I don't like the color. THen I'll paint the silver part and put some decals on it and run the pants off it after the lower unit is resealed, if it's o.k.
Later,
JBJ

 

[wbeaton]

Re: '54 evinrude 25hp troubles

It's looking good. I wish mine was that nice. Here is my cowl.

I also found that the low speed jet influenced the high even at WOT. It was quite a dance. I found setting the high jet slightly rich at WOT throttle made setting idle easier. If I set mine at WOT to the highest speed achieved then it would starve at idle. Turn it slighty rich and I could idle lower. It was the hardest carb I've ever set. Could be that all these carbs/motors react a little different. The newer carbs seem a little more refined and probably run better.

Keep at it.

 

[jay_merrill]

Re: '54 evinrude 25hp troubles

JBJ, the broken piece on your carb is a possible source of your problem. I recommend choking your motor at idle a little to see if it runs better. If it does, you are probably sucking air into the carb body from the throttle butterfly shaft. This is a common problem in older motors, even when there is no damage such as that on your carb.

 

[tmcalavy]

Re: '54 evinrude 25hp troubles

Hey JB,
What does that carb look like? Can you post a pix? Might be less aggravation to fit a later 30 or 35 hp carb on it, say 55-58 if they are compatible. I know you like to keep stuff original, but if it runs better...

 

[jbjennings]

Re: '54 evinrude 25hp troubles

Interesting question, Tim. I'll post a pic of the whole carb tomorrow. I'm not that particular about having it flawlessly original. If the newer carb will fit and make it run smoother, seems like that would be better than original! I'm even going to put '53 decals on it because I like them better. I don't care for the goofy looking lightning bolt or the evinrude "bird" on the '54. Just my personal preference so I hope nobody gets their feelings hurt in case their great grandpa was the designer of those decals. And I can always change 'em back if I change my mind. Original is neat. On a side note--I have always wanted a late 40's/early 50's chevy pickup but after driving one a few years ago that was all original, I don't want one that is original. It drove like an army tank! I'd like to have an old body on a newer chassis with a good 'ol carbed 350 and newer 5 speed standard transmission. It would be neat to pull my old motors with it, especially if I found myself a good old aluminum boat like your's to put them on. Just Dreamin'.
Good idea on the carb.
thanks,
JBJ

 

[Xcusme]

Re: '54 evinrude 25hp troubles

Question 2-- I can't seem to get the motor to idle down smooth. I have cleaned the carb. My gasket on the high speed nozzle between the 2 carb halves isn't too sporty. When I turn the throttle down a little it will idle down for a few seconds and then die with a hard cough. If I richen it up with the slow speed knob it will not idle down without dying quicker. It will fast idle with the high speed valve totally closed.

JBJ

Sadly, I don't have a pic(internal) of your carb to verify a thought. The gasket , probably a donut or thick cork-fiber type that seals the high speed riser tube going to the high speed jet can be a real problem. The gasket has been referred to as the Boss gasket. It seals , what I call the High speed riser cast tube in the middle of the lower carb bowl with the upper carb body. If it's not sealing, fuel can be drawn into the carb throat at idle throwing off the idle mixture big time, making it way too rich. As i mentioned, this is just speculation on my part, a wild guess really, not having an exploded view to look at.

 

[tallcar]

Re: '54 evinrude 25hp troubles

Those packing gaskets for the carbs are available from Sierra I believe part number 18-7106 ???? 10 per pack.

 

[wbeaton]

Re: '54 evinrude 25hp troubles

Sadly, I don't have a pic(internal) of your carb to verify a thought. The gasket , probably a donut or thick cork-fiber type that seals the high speed riser tube going to the high speed jet can be a real problem. The gasket has been referred to as the Boss gasket. It seals , what I call the High speed riser cast tube in the middle of the lower carb bowl with the upper carb body. If it's not sealing, fuel can be drawn into the carb throat at idle throwing off the idle mixture big time, making it way too rich. As i mentioned, this is just speculation on my part, a wild guess really, not having an exploded view to look at.

His carb doesn't have that seal. It came later. There is also very little room in there for it since it wasn't designed for it. Some folks add it anyway when rebuilding those carbs, but they may have to modify the seal (make it thinner) to get it to work.

The lightening bolt is my favourite part! lol

 

[tmcalavy]

Re: '54 evinrude 25hp troubles

Well I'm curious to see your carb since I have a 58 35 hp Johnson super seahorse in the shop that runs poorly at idle, and a 56 Lark 30 hp that is my next project. Their carbs look kinda similar but haven't looked up close just yet. Seeing your earlier carb would give me an idea of any carb changes, if there were any. If it turns out the carbs are the same, I have an extra one for the 58 35 hp, that you can have if you need parts for yours or a replacement. It's dirty, haven't cleaned it yet, but appears to be all there. If I can get the Lark running, I'll be real close to having twins 30 & 35 hp on the Texas Maid runabout...will have to extend the legs on both though. Keep this thread going, I'm real curious about the carb settings.

 

[jbjennings]

Re: '54 evinrude 25hp troubles: UPDATE!

Re: '54 evinrude 25hp troubles: UPDATE!

Update.....Good and bad news:

The good:

I came home from work and link-n-synced the carb (it needed it bad) and put a thinner, good gasket on the high-speed nozzle as suggested by everyone. Buttoned it back up and went to the lake.
It fired up on about the 4th pull and I was able to just push the choke in and it ran...I was pleased since this was different from usual. I was able to get it to idle much better and it would idle below the start position on the throttle. I decided to set the high-speed jet with a little fast run down the channel so I could really tune the low-speed perfect........

The bad:

The clutch started slipping just off idle and I never got even close to plane. I idled back to the ramp and went home. I'm pretty disappointed.
It did idle pretty darned low for a 25 2-stroke and didn't cough like usual, so I am confident that the powerhead is fixed and I'm well-satisfied with the idle already. thanks for all your advice. Incidentally, you guys were spot-on with the aomci guys as far as similar advice. thanks for all the help, I can't wait to get the lower fixed and plane it out!
By the way Wayne---Thanks for the parts manual---AGAIN!!!

Tim, here's some pics of my carb. You need to get those 35's fixed!
Later,
JBJ