Evinrude 25 1975 Armature plate wiggle.

[redfisher2003]

Last week I identified a weak spark in the #2 cylinder and I have tracked the problem to that set of points and condenser. When I try to set them I find play in the armature plate itself. While the plate rotates it also will move side to side, and the point gap changes considerably. There are four screws attaching the armature plate to a ring which rotates when the throttle is advanced. In my book it shows a nylon retainer that can be replaced on a different model than I have. Does anyone know if all magnetos have a nylon ring that insures alignment of the armature plate as it moves with the throttle? There was no nylon part with the ring that holds the armature plate down. The ring is held in place by a circular brass retainer that is screwed done by 3 screws to the powerhead. The ring seems metal but perhaps not. <br /><br />Also, anybody know if I can see a picture of this motor on the web to checkfor the part I think I need.

 

[Joe Reeves]

Re: Evinrude 25 1975 Armature plate wiggle.

Red..... The following may be of interest to you.<br /><br />(Magneto Armature Plate)<br />(J. Reeves)<br /> <br />If the armature plate has a a loose fitting, wobbling motion (the plate that the points, coils etc are attached to), it is usually caused by a slightly worn support ring. This allows the point setting to change erratically as the armature plate turns.<br /> <br />The cure is to remove the armature plate so that the support which is attached to the powerhead with 4 screws is visible. Then, with a screwdriver and hammer, or some tool of your choosing, and looking straight down at the support ring, make an indentation at what would be called the 12, 3, 6, and 9 O'clock positions. Install the armature plate and check for a smooth turning wobble free movement.<br /><br />You may need to do that procedure a few times to obtain the proper fit (not too tight, not too loose), but it's worth the effort.

 

[wayne h]

Re: Evinrude 25 1975 Armature plate wiggle.

had the same problem with my little 9.5 but i was not so lucky to have a worn out ring. instead the armature plate that went into the ring was lost in the armature plate looks like its a brass ring thats molded into the aluminum armature plate.i am sure thats not what it is because they say aluminum and brass dont mix but eather way it was lost in there with no pix. it had to be replaced. thank god for a parts motor

 

[G DANE]

Re: Evinrude 25 1975 Armature plate wiggle.

I discovered Joes Excellent fix gets even better if I gett some of the ultrathin brass coil material and swept one turn around motor boss before putting stator plate back on. Now all play is gone.

 

[redfisher2003]

Re: Evinrude 25 1975 Armature plate wiggle.

Thanks to all,<br />Joe I am going to try your idea today. That is a creative idea that really did not occur to me.<br />G Dane you started me down this path last week end and I do think I will solve this problem ultimately. By ultra thin coil material do you mean wire used in coils? Secondly, when you suggested this was one of my issues I was interested in low compression, 80 psi per cylinder. I saw where you rebuilt a 1974 25 hp evinrude in the forum a while back. I have rebuilt lawnmower motors and old trucks, is it really much of a problem to pull the pistions and do a ring job. I do want to have a idle speed for trolling with this boat motor should the ignition issue not solve everything.

 

[redfisher2003]

Re: Evinrude 25 1975 Armature plate wiggle.

G Dane and Joe,<br />The techniques stopped the plate wiggle and the motor does run smooth. I used a nail set to make the indentations and some very thin copper wire around the motor boss. I think it probadly did not fire on both cylinders all the time before I corrected the armature plate wiggle. It still does not have a very slow idle speed but I do need to check it at the lake in gear. I also have to to see if it will run a full throttle for an indefinite period with out cutting out. That might have to wait due to rain in the area today.<br /><br />I rechecked the compression again still 80 psi. If it does idle slow enough higher compression probadly does not matter to me (it is on a light plywood boat and speed is not the goal). It does start easily. <br />Thanks again,<br />Redfisher

 

[G DANE]

Re: Evinrude 25 1975 Armature plate wiggle.

redfisher2003<br /><br />Glad to hear it worked for you. Actually I ment thin sheet material, made for repairing worn bosses. <br /><br />Joe had an excellent thread here for adjusting low speed jet. Something like: Turn lowspeed adjustment needle carefully all the way in to stop, without turquing, back it out 1 1/2 turn. Let motor warm up and run it wot for a minute. Go down to iddle, boat moving foreward unrestricted in gear. By 1/8 turn at a time, turn screw in again. After every adjustment, wait for motor to react, and iddle smooth. If iddle gets to high, adjust speed. When motor starts to surge or miss, back out 1/16 turn, sweet spot should be around there. You will probably be surprised that most problems are caused by too rich iddle mixture, making it load up.

 

[redfisher2003]

Re: Evinrude 25 1975 Armature plate wiggle.

Final report: Motor now runs fine at all speeds with no problems. I guess the low compressions is not too bad.<br />Frank