1962 28 hp spark issue

[Woodstock60]

This one has me baffled. followed procedure to wake a sleeper, as I have many times before. rebuilt carb, new coils, regapped points, sprayed in double oil mixture into carb intake while carb was off and cylinders. put in new plugs and added electric starter, Changed all gas lines to new rubber and cleaned the old style feul pump. Fired her up and she ran smooth for all of 8 seconds, after a couple of tries to restart I put on the spark testers and had no spark to either cylinder. While I was here I did a compression test and both cylinders were 118 psi.....perfect, so I took off the flywheel again and whent through the whole ignition system again this time changing the spark plug wires and checking all the other wires for cracks or shorts. changed the condensors and triple checked everything ( I did not change the points because they looked good. ) I put it all back together and fired it up and it did the same thing, ran good for 8 seconds and then lost spark to both cylinders. WTF Im not sure what I am missing. I did a second compression test and both cylinders were 104 psi....both cylinders lost 14 psi just like that. could this be some kind of reed issue? I am ready to completely change the whole throttle plate and all the electronic components, but I just dont get why both plugs are loosing spark? Does anyone know what I should be testing here? what parts would control both cylinders? flywheel maybe? everything appears to be in good condition. Thanks for the help... Serial # is RX-10R Ronnie

 

[F_R]

Re: 1962 28 hp spark issue

There are only a couple of things that can kill the spark on both cylinders at the same time. Sheared flywheel key would be #1, but surely you would have noticed that. The stop button/ignition switch would be #2. Beyond that, it would have to be something bizzare and hard to guess. Or dumb, like not tightening the points' screws.

It is not the flywheel unless the keyway is all battered (shearing keys). The magnets never go bad, if that is what you are thinking.
It is not the reeds
It is not the throttle plate (assuming you mean the armature plate that igniton mounts on)----unless it is all wobbly or something.

 

[Woodstock60]

Re: 1962 28 hp spark issue

Flywheel keyway in good shape, magnet had some rust prior to me starting, obviously i lightly sanded off.
I was thinking reeds because there is a vaccume line coming out of the front of them going to the cut out swicth. one of the tests I tried was to pull it off the cut out and put my thumb on the end while I cranked the motor and I felt no suction. I didnt know if it was the suction that engaged the switch or vice versa. and does the switch kill both cylinders or just one.
The armature plate is not wobbly, and everything looks good, that being said looking good doesnt mean a thing here. M y only other thought is a short somewhere. I guess Ill have to start with a different armature plate and all new points and wiring. Thanks for the help and let me know if you think of anything else. Ive got way too many hours into this with fishing season moving into full swing! Ronnie

 

[samo_ott]

Re: 1962 28 hp spark issue

The cutoff switch kills one cylinder (top one I believe). Have you looked at the stop button/ignition switch as FR mentioned? That's the most common common area. Otherwise both ignition circuits are independent.

 

[Woodstock60]

Re: 1962 28 hp spark issue

I tried disconnecting one of the wires to the kill switch, still no spark.

 

[F_R]

Re: 1962 28 hp spark issue

The vacuum cut-out switch doesn't do a darn thing unless the motor is in runaway condition. If that happens, the high vacuum closes the switch and kills one cylinder till it slows down. It has absolutely no effect on the other cylinder at any time.

As said, you have two completely independent igniton systems. The only common items are the flywheel, stop switch circuit, and breaker cam. Something is being overlooked. I suggest getting out the multimeter and make sure the points have zero resistance when closed and about one ohm when open. Having worked on literally thousands of those magnetos, I just don't know what the problem is with yours. Um....speaking of the breaker cam, the key is in it, isn't it?

 

[Woodstock60]

Re: 1962 28 hp spark issue

This particular crank has the cam built right in, it does not slide off like most. I will test everything, and replace everything starting with the points and report back. I will figure this out. thanks for the help, I know where not to look now. Ronnie

 

[samo_ott]

Re: 1962 28 hp spark issue

I think they all slide off. Otherwise how would you get the ignition plate off? However I looked at the RX-10 manual and it did not show it. (btw, if you want the parts manual, PM me your email address and request)

 

[Woodstock60]

Re: 1962 28 hp spark issue

As you can see the cam is part of the crank on this one.

 

[samo_ott]

Re: 1962 28 hp spark issue

Hmmm... Sure looks like it!

 

[Woodstock60]

Re: 1962 28 hp spark issue

Well I have success, she's running smooth. as for what was wrong I don't know for sure but what i changed for the final time was the armature plate, points, one of the coils that i thought looked good and the cutout switch wires so it was one of those things. the kill switch is fine. I have one more small problem. There is a hose that runs from the block under the carb way down , to the side and up near the top just under the armature plate, I can see a split in the hose right after the clamp on the bottom and there is oil gathering under it. I need to replace it, but I don't know what it is for. Can anyone tell me the purpose of this hose? Ive seen it on eariler models made out of metal. Ronnie

 

[samo_ott]

Re: 1962 28 hp spark issue

It' to get oil to the upper bearing. It should be fixed.

And that's great you got it running