Super A magneto problem

Wed Apr 02, 2014 8:08 pm

So. Tractor was running great until I left it out in the rain for about 3 days. After that she wouldn't fire. I figured something that got wet that wasn't supposed to. I narrowed it down to a weak spark, so something was clearly wrong in that area. I popped the distributor cap off to check it, didn't notice much, cleaned it anyways. I then took the rotor cap and nudged the center of the arm a wee bit out (so it would be closer to the center point on the cap) and It fired right up. It was running just fine for about 1 minute, then it shut off, I had the gas off, oops haha. So I turned the gas on and she fired right back up again. After that the tractor ran for about an hour until I finally shut it down. I went to start it again and nothing. She just turned and turned and turned. I pulled the cap off again and found little metal shreds all over the inside. They were around the entire inside, like the rotor decided to machine the center of the cap. Could this be solved by just getting myself a new cap/rotor? I also noticed the arm on the rotor had a small crack on that little rivet thing that holds it on, could that cause a problem?

I think its having poor contact with the center point on the cap.

I think I have the H4 magneto, but I'm not sure.

Re: Super A magneto problem

Wed Apr 02, 2014 9:43 pm

Sounds like maybe cap and rotor

Re: Super A magneto problem

Wed Apr 02, 2014 9:46 pm

The center of the cap should have a little carbon button that sticks out for the rotor to contact in the center. I suspect yours broke off or wore off. You need to also check the rotor to see if it has a smooth spot where it contacts that carbon button or if it has worn through and is cutting it up. It does not want much pressure where it contacts that button.

Re: Super A magneto problem

Wed Apr 02, 2014 11:49 pm

John *.?-!.* cub owner wrote:The center of the cap should have a little carbon button that sticks out for the rotor to contact in the center. I suspect yours broke off or wore off. You need to also check the rotor to see if it has a smooth spot where it contacts that carbon button or if it has worn through and is cutting it up. It does not want much pressure where it contacts that button.


Thats what I figured. The carbon button looks fairly okay, but the spring seems to have lost its "springyness". The carbon button doesn't push out as far as it can go. I'm probably just gonna replace both parts. I assume I have the H4, but how can I know for sure? I just don't wanna pull the trigger on parts that won't fit right. I already did that once lol.

Re: Super A magneto problem

Thu Apr 03, 2014 10:49 am

It will have "H4" stamped into the serial number. Post a picture and we will tell you for sure.

Re: Super A magneto problem

Thu Apr 03, 2014 1:53 pm

First 3 photos are my tractor, the last one is a google image of what it looks like.

Image

Re: Super A magneto problem

Sun Apr 06, 2014 5:15 pm

Yes, you have an H4 magneto.

Re: Super A magneto problem

Sun Apr 06, 2014 5:20 pm

Rick Spivey wrote:Yes, you have an H4 magneto.


Figured, thanks! New parts on the way. Hopefully it will remedy the issue.

Re: Super A magneto problem

Mon Apr 07, 2014 12:29 pm

I had a similar problem on my cub. and the problem turned out to be a cracked insulator for the kill switch screw. The insulator had a hairline crack and it would short just enough when it rained to allow an inconsistent\weak spark. I don't have a drawing for the H4 but the part shown below was for the J4. But there has to be a similar insular for the H4.

Kill Swtich Insulator.JPG


I found the same part for the H4 is is 51A or 51 in the diagram below:
H4 Kill Switch Insulator.JPG
You do not have the required permissions to view the files attached to this post.

Re: Super A magneto problem

Tue Apr 08, 2014 7:23 pm

Awesome thanks. The coil cover gasket was ripped and shredded so hopefully the new one I got will stop the water next time.

Re: Super A magneto problem

Thu Apr 10, 2014 12:23 pm

Yeah, so something isn't quite right, I think I have a grounding/short issue here, I have ZERO spark. I think I'm gonna have to pull the magneto off, and take a more thorough look. I have a question, if I remove the magneto, will I have to re-time it after? And If I do, should I follow this?: http://www.yesterdaystractors.com/articles/artint7.htm

Re: Super A magneto problem

Thu Apr 10, 2014 10:03 pm

Found the problem. Bad gaskets + rain for 3 days =

Image

Yep, water in the points housing.

Re: Super A magneto problem

Fri Apr 11, 2014 12:17 pm

Usually moisture in the points housing will not stop a spark, unless it was standing in puddles in there. However, if the moisture got inside the coil housing, that is another story. My loader cub sets under a lean too on the side of my shed, and I keep a layer of bubble wrap plastic over it, held in place with reusable cable ties. Makes it much easier to start in high humidity, or just after a rain or even early in the morning before the dew has dried good.

Re: Super A magneto problem

Fri Apr 11, 2014 12:27 pm

Well I can tell you John, it was more than a little moisture lol. The cavity was filled up halfway. There probably is also water around the coil too. Any tips for drying it out short of tearing the entire thing apart?

Re: Super A magneto problem

Fri Apr 11, 2014 10:46 pm

Lay it outside on a nice warm sunny day, or if you have a dehumidifier turn it down to 35% and set it over the vent.