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1972 Evinrude 25202R needs help!

C

CleverName

New member
First and foremost, a thank you ahead of time to anyone who reads this post and can point me in the right direction. Now, I'm running a 16' Jon with a 1972 Evinrude 25HP 25202R. I'm having 2 (what I believe to be separate) issues. First, when I try to start the motor, it'll pull star just fine and rev up decently. It spits good water, and sounds solid. Now, when I lower the throttle to the point where it says "Shift" or "Slow" the motor starts jerking back and forth pretty rough, and starts to backfire loudly. Once it begins that, it dies out. It's gotten to the point where it will take me 4 or 5 starts on the water and having to keep the RPM's a little up before I can throw it into gear and (hopefully) she gets going. Not a good feeling if there's a barge headed your way. That being said, when it does start up and get going sometimes it will seem like the motor will rev up and the prop not be pushing the boat, if I give it less throttle then throttle back up it will start to push again, just seems sometimes like the motor still revs but the prop isn't pushing. I've read something similar that claims there could be an issue with a bushing behind the prop and that I may need a new prop? Any help on these matters would be awesome, Thank you!
 
So I've read some other posts in this forum about similar issues, and I'm going to run it after backing the low speed needle out a full turn. Hope that helps, otherwise I need to read more about my motors other issue... Thanks again and hope I get it resolved!
 
Use Champion J6C spark plugs in that engine, gap set to .030

Make sure the flywheel key isn't damaged and torque the flywheel nut to factory specifications.

********************
(Point Setting Of Magneto Models)
(J. Reeves)

Note that there are other ways to set points such as using a ohm meter or timing light... however, the following will result in a setting so close to being exact that one could not tell the difference.


Make sure that your feeler gauge is absolutely clean so as NOT to transfer oil/grease to the points.

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE 1: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

NOTE 2: Should the cam have the word TOP embossed on the top of it, that is a cam that could be installed upside down and this is simply telling you which side is up. It is not a position where one would set the points.

********************
(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
 
That motor is running much too fast for the slow speed needle to have any effect. OK, so guess you are retarding the throttle and that makes it sneeze and quit, right? There is a problem in the idle circuit of the carburetor. OR the carburetor throttle shaft is not closing as it should.

Second issue (not pushing the boat) is a broken drive (shear) pin, OR a slipping propeller hub.
 
fdrgator said:
That motor is running much too fast for the slow speed needle to have any effect. OK, so guess you are retarding the throttle and that makes it sneeze and quit, right? There is a problem in the idle circuit of the carburetor. OR the carburetor throttle shaft is not closing as it should.

Second issue (not pushing the boat) is a broken drive (shear) pin, OR a slipping propeller hub.
Click to expand...

Yes, once I try to lower the RPMs even close to the "SHIFT" or "SLOW" marking on the tiller handle, it backfires like that and jerks back and forth, which then results in it dying. It'll start right back up, first or second pull every time. I can try to get a better video tonight, I'll admit that video wasn't very telling.
 
RE-read what I had to say in post reply #4......................

If you set the points and went through the carburetor adjustment as I stated..... taking into consideration that the flywheel key (timing) hasn't been damaged..... and that something within the carburetor hasn't been overlooked, that engine should be running perfectly.

Note that the Fast, Slow, Shift marking on the tiller handle means nothing more than to advise you which way is fast. Those markings are not actually indicators of when to shift etc.... ignore them.

Turning the adjustable slow speed needle valve 5 turns out would be more than enough to flood out the engine if fuel was flowing through the carburetor's passageways properly.

There is a scribe mark on the cam that slides against the roller that causes the throttle butterfly to open. The throttle butterfly should just start to open when that scribe mark is dead center with the roller, not before or after.
 
joereeves said:
RE-read what I had to say in post reply #4......................

If you set the points and went through the carburetor adjustment as I stated..... taking into consideration that the flywheel key (timing) hasn't been damaged..... and that something within the carburetor hasn't been overlooked, that engine should be running perfectly.

Note that the Fast, Slow, Shift marking on the tiller handle means nothing more than to advise you which way is fast. Those markings are not actually indicators of when to shift etc.... ignore them.

Turning the adjustable slow speed needle valve 5 turns out would be more than enough to flood out the engine if fuel was flowing through the carburetor's passageways properly.

There is a scribe mark on the cam that slides against the roller that causes the throttle butterfly to open. The throttle butterfly should just start to open when that scribe mark is dead center with the roller, not before or after.
Click to expand...

I definitely will. I'm at work and can't peek just now. Just trying to eliminate other possibilities by clarifying. Thank you for the info though I hope it resolves this.
 
Ok step 1, I don't have a flywheel puller and can't muscle it off. I took the carb off and have peeked around it, blew it out with some cleaner and my air compressor. I set the low speed needle back to 1 1/2 turns out from being seated gently. Where on the carb could the trouble spot be? It all appears to be clean.
 
Ok, Last question as I'm going to get the puller today to take off the flywheel. Could the issue be found with the low speed needle valve "bearing"? I have taken the needle out and only have that plastic bushing come out that keeps the needle from loosening due to vibration.
 
That adjustable S/S needle valve does have some bearing on the problem but is not the cause, UNLESS you or someone else has rebuilt that carburetor recently or at some time in the past because..............

You have mentioned that small nylon bearing that slides onto the tip of the needle valve comes out when the needle valve is removed...... it shouldn't be coming out!

That small bearing fits in a portion of the carburetor very tightly. It is not there to prevent the needle valve from loosening.... it is there to keep the needle valve tip from vibrating which would damage the taper of its tip. It fits so tightly in the carburetor that it must manually be removed if it needs removing.

The fact that it same out when you removed the needle valve makes me wonder if it was installed simply because it came with a repair kit. And, if so.... it is highly likely that the bearing is already installed and you are inadvertently trying to shove in another one... and again "if so".... that would make it impossible for that slow speed needle valve to actually seat, then be adjusted properly.
 
Last edited:
The one that slides over the tip is not the one that is coming out, the one that comes out is more like a collar at the front of the carb. However I'm looking inside the carb and can't tell if it has a bearing in their already or not, I slid a screw in and tried to grab and see if anything was in there but the screw just locked up and I had to turn it back out. I've added a picture.
2ev9ms3.jpg
 
Okay.... then you're speaking of the RED nylon fitting that sits in the top front portion of the carburetor. Yes that one's purpose is to keep the needle valve from turning.

Many carburetors do not use the smaller nylon bearing that I thought you were talking about. I'd need to check the parts book.
 
kimcrwbr1 said:
The nylon bearing keeps it from leaking vacuum pressure at slow speed item #35
http://www.marineengine.com/parts/j...202R&manufacturer=Evinrude&section=Carburetor
Click to expand...
Yes, that’s the one I’m referring to that I cannot see, ortell if it is there. The red nylon one that JoeReeves is referring to is fine,I have it and it slides into place just fine. But, in reference to part #35 Ihave one that I can slip in, but I can’t tell if there is already one in theport or not. As I stated previously I slid a screw in, thinking hey if it’splastic I can thread a little into it and pull it out, but I’m not gettinganything. I peeked in to see if I could discern the little plastic “bearing” asit’s called, but I can’t see anything, hence the picture. If there isn’t one inthere, I have one I can thread in. But, I don’t want to create a situation likeJoeReeves was talking about where now I have 2 of them down the low speedneedle port. I apologize if this is confusing, again I’m very frustrated.
 
Your 1972 25hp model does incorporate that small almost transparent nylon bearing/bushing in its carburetor. In the picture you provided, although excellent, it is still difficult to see but I do sort of detect a reflection that indicates it is there.

A screw easily goes through that thin nylon and hooks onto the aluminum. I use a very small tap, not sure of the exact size (a 440 I think), but at any rate one that I can hand screw into the bearing to pull it out of there. You have one (bearing) so you can figure out the tap size.
 
bobbyc said:
When it starts running badly at low speed, does partially chocking it help?
Click to expand...

I haven't tried doing that yet. I can try that next, still finding time to try and get that little "bushing" out with a 4-40 tap. The tap I had didn't look long enough so I put it back, but now I'm looking and it should work. Running back to Ace Hardware in like a half an hour. Trying to fix a motor on a budget is tough these days. Couldn't even rent the pulley puller to take off the flywheel, they wanted $119.99 just to rent it. Seems like highway robbery.
 
So, I grabbed the 4-40 tap and discovered there was no part #35 in the carb. So I installed one and seated the needle, took it out 1-1/2 turns. I ran the motor and the problem seemed a little lesser, and then it continued again as usual. I noticed a leak coming from one of my hoses so I took it off, cut it down and re-clamped it onto the nipple it was on. Hoping this to finally be the culprit, alas it is not. I'm assuming the last step here is going to be pulling the flywheel and checking out the key like joereeves had originally suggested. I hope this sheds light on my situation. Otherwise who knows, I am getting a lot of blue smoke while running it and a pretty rythmic miss it would seem. The motor is running NGK spark plugs and I'm not sure what they're gapped to. Going to have to check that out, but I'm going to pick up some Champion J6C plugs on payday. Here is a link to how the motor is (not) running now.

https://youtu.be/zBZ_A5Evsu4
 
Ok. I'm waiting on new spark plugs to come in that I ordered. I ordered some Champion J6C plugs as Joereeves suggested, and I'm picking up a pulley puller to grab this flywheel and get it off. I will continue this (mis)adventure shortly.
 
New plugs are in and gapped properly, engine still doesn't want to run. I'm nearing my wits end here. Thanks for all of your help. Next question, who needs a mechanics special?
 
joereeves said:
Use Champion J6C spark plugs in that engine, gap set to .030

Make sure the flywheel key isn't damaged and torque the flywheel nut to factory specifications.

********************
(Point Setting Of Magneto Models)
(J. Reeves)

Note that there are other ways to set points such as using a ohm meter or timing light... however, the following will result in a setting so close to being exact that one could not tell the difference.


Make sure that your feeler gauge is absolutely clean so as NOT to transfer oil/grease to the points.

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE 1: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

NOTE 2: Should the cam have the word TOP embossed on the top of it, that is a cam that could be installed upside down and this is simply telling you which side is up. It is not a position where one would set the points.

********************
(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
Click to expand...
Do you know if the air screw is supposed to have any type of o-ring on the threads or a tiny one before the threads or none at all?
 
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