Circa 1954 f cub won't stay runnung

Tue Jun 18, 2013 11:19 am

Replaced the coil, points & condenser and plugs and cleaned the carb. Timing is on TDC. Have fresh gas. Compression is good. Engine will start but quits as soon as I try to move it and will just quit by itself after a minute or two. Getting spark but plugs are black and smell "gassy".
I'm going nuts!
Any thoughts are most appreciated.
David
ps new distributor cap and spark plug leads as well.

Re: Circa 1954 f cub won't stay runnung

Tue Jun 18, 2013 11:53 am

Welcome to the Forum!

-When you say compression is good, what are the actual numbers on each cylinder?
-Magneto or Distributor?
-Did you use solid copper core plug wires?
-Does the tractor roll freely when pushed? (Brakes not locked up)
-When it quits, does it sputter to a stop, or just quit like you turned the ignition off?

Re: Circa 1954 f cub won't stay runnung

Tue Jun 18, 2013 11:54 am

David:

G'day to you and welcome :)

Sounds to me like you have fuel starvation issues. Did you clean the metering jet? Both the larger orifice as well as the small longitudinal orifice. Clean it with a piece of telephone wire/twisted pair. I would also be checking the needle and cage for varnish flakes or other crud which could be the problem.

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Re: Circa 1954 f cub won't stay runnung

Tue Jun 18, 2013 11:58 am

Check for a loose or broken wire on the ignition switch or perhaps a bad switch....Jump it out and see if it quits when moving the tractor...2 1/2 cents worth...Dave

Re: Circa 1954 f cub won't stay runnung

Tue Jun 18, 2013 12:11 pm

Welcome to the forum. Since we're throwing out ideas. Are the plug wires in the correct order on the distributor cap for the correct firing order? Are the new plug wires seated all the way into the distributor cap?

Re: Circa 1954 f cub won't stay runnung

Tue Jun 18, 2013 1:15 pm

RaymondDurban wrote:Welcome to the Forum!

-When you say compression is good, what are the actual numbers on each cylinder? All four pump up to about 125
-Magneto or Distributor? Distributor
-Did you use solid copper core plug wires? No teisted
-Does the tractor roll freely when pushed? (Brakes not locked up) yes I have pushed it.
-When it quits, does it sputter to a stop, or just quit like you turned the ignition off?
Usually seems to hunt then quit, other times it just stops.

Thanks for your questions.

Re: Circa 1954 f cub won't stay runnung

Tue Jun 18, 2013 1:17 pm

Scrivet wrote:Welcome to the forum. Since we're throwing out ideas. Are the plug wires in the correct order on the distributor cap for the correct firing order? Are the new plug wires seated all the way into the distributor cap?

Yes they are and when it runs it is firing smoothly.
Thanks

Re: Circa 1954 f cub won't stay runnung

Tue Jun 18, 2013 1:19 pm

If it hunts then quits, then I'd say you have a fuel starvation issue. Pull the plug (metering jet) on the side of the carb with the fuel turned on and a pail to catch the fuel as it runs out. It should be a steady, continuous stream. Turn the fuel off, and with the jet still out of the carb, blow it out with compressed air and then reinstall and try again.

Re: Circa 1954 f cub won't stay runnung

Thu Jun 20, 2013 3:56 pm

Well, I'm a little embarrassed. Somewhere I got the idea the point gap was .030. No wonder the poor thing wouldn't run. Found a manual and re-gapped at .013 and it runs like new.
Thanks for all the help and sorry to have bothered all of you with my mistake.

Re: Circa 1954 f cub won't stay runnung

Thu Jun 20, 2013 4:10 pm

Don't be embarrased, if you asked a roomful of Cubbers how many couldn't get their Cub started only to find they hadn't opened the gas valve at the sediment bowl......there'd be a lot of hands in the air (including mine). :D

Bob

Re: Circa 1954 f cub won't stay runnung

Thu Jun 20, 2013 7:47 pm

Image to what Bob said .. :shock: that and a few other major :big shy: embarrassing moments :lol:

Re: Circa 1954 f cub won't stay runnung

Thu Jun 20, 2013 8:35 pm

I thought the points gap was .020...can someone verify which it is?

Re: Circa 1954 f cub won't stay runnung

Thu Jun 20, 2013 9:00 pm

Magneto : .013
Distributor: .020

He hasn't indicated in this thread whether it is a magneto or distributor aka battery ignition.

Re: Circa 1954 f cub won't stay runnung

Thu Jun 20, 2013 9:12 pm

Ahhh...thanks Rudi! Forgot about the mags!