Rough running F-20

SW EM

Member
Good morning, I have a small problem I thought I would run past you guys before I did anything about it. I overhauled my F-20 last summer and I"ve driven it periodically since, but it sounds rough unless it is under a load. In my opinion I believe the magneto is set one notch to advanced. Plus, sometimes when I"m crankstarting the tractors it will puff and spin the crank backwards.

I am contemplating on whether or not I should install one of Nebraska Kirk"s rebuilt mags and retime everything to make sure. But, could this issue be the carburetor? What are the standard settings for the adjustment screws?

I would just like this F-20 to start on command and be a sweet runner like some I"ve seen at shows.Thanks for your help!
 
(quoted from post at 10:29:39 07/19/14) So I should retard the Magneto one bolt hole?


one whole entire hole is pretty drastic. the bolt pattern is staggered between the two so you only have to go a small bit to get another set of holes lined up. just remember when you do that you wont put the bolt back in the hole it came out of
 
I set I back just a tiny bit and it seemed to help. Is it OK if I idle the tractor with the Mag lever halfway on, and then turn it all the way on when I drive or work the tractor? It can't hurt the mag to have it in the halfway position for a long time can it?
 
(quoted from post at 12:55:06 07/19/14) I set I back just a tiny bit and it seemed to help. Is it OK if I idle the tractor with the Mag lever halfway on, and then turn it all the way on when I drive or work the tractor? It can't hurt the mag to have it in the halfway position for a long time can it?

It won't hurt it at all, that is the reason for the lever, timing advance and retard. Partial advance with the tractor idling and full advance with the engine running wide open!
 
I had the same problem with my F-20, took me a while to figure it out. My manifold was not drawing up tight against the block. One way to check is to spray some starting fluid around manifold, if the engine revs up, you have a leak. I removed the manifold and had it staighten out at a machine shop. The F-20 ran great after that.
 

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