Cub is hard to start

Greg Crowder

New User
Just got home with 2 new toys from an old estate. JD 1010 RS and a 1951 Cub. On the Cub after checking the fire making sure that I am getting gas to the carb I go to crank and it fires but won't start up until after many tries. Once it starts i can shut it down and every time I crank it cranks right up.
I'm thinking it may be a head gasket or valve issue. what direction should i go in first.
 
I'd go in every other direction before I went after a head gasket or valves because of a starting problem. Mag or distributor, I'd go over the ignition system. Carburetors don't discriminate, that is, if the tractor will run, it will start (from a carburetion standpoint). Ignition is another matter. Inspect, adjust and clean points, maybe change plugs, etc.
 
First I would run a compression check. That will tell a lot. If that is reasonable start with fuel. Clean the filters one at the fuel line to carb connection and there may be a screen at the top of the fuel bowl. Clean the main jet. All very simple. Next would be a complete tune up including setting the valves. Post a progress report.
 
Are you using the choke when it is cold? I would chc=eck to be sure it is closing if you are. These things usually start immediatly. Valves and gaskets are not on my list at all. Jim
 
Check the arm on the carb that the choke is fastened to they do get loose. Sounds like trouble with choke cause you say after it runs it will start easy. Mite need to remove the hose into the carb so you can see he choke response when you pull the lever.
 
after personal experience with my cub what i found was the little piece that connects the choke rod to the carb was slipping on the shaft, you can pull the rod, but it isnt actually closing the choke flap in the carb, this is common on cubs and the piece is available from several sites, the fact that once it does get started it will fire right up virtually eliminates everything else
 
Talk about throwing the baby out with the bathwater! The tractor is a little hard to start, so you're ready to tear the engine down and do a complete overhaul? No offense, but that's just crazy talk.

First off, do you know what the choke does, and how to use it? Most carbureted gasoline engines require some amount of choke to start up cold, and start just fine warm.

The key is learning what your tractor wants at startup. Unless the previous owner can show you, you're stuck figuring it out on your own by trial and error.

Try giving it a little blip of choke at first, and see where it goes from there. When it finally catches and runs you might have to feather the choke on and off to keep the tractor running. Not enough and it will starve for fuel. Too much and it will flood out.
 
I had a farmall A that became hard to start after it sat for a few years of which I only started it occasionally. Found one day that it was unusually hard to start. (Yes the choke was fine) WHEN I finally got it started, I noticed it was missing. Long story short, it seems a valve guide got tight , the valve stuck open and the push rod fell out of place. Freed up the valve, straightened the pushrod :) and she was starting and running fine again.
 
re the previous post, seeing as it was an intake valve stuck open, the fuel was being pushed back away from the intake back to the carb even though I was choking it.
 

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