Hard Starting Cub

[Phillip W. Lenke]

Well, I have a cub that is hard starting but runs great after it starts. Any thoughts.
Here is what I have checked, plugs look good light brown,main jet .03-.032
spark good. New rings and valves spring 2005
Carb floods when starting, also I took the plugs out after flooding , thinking they would be wet, dry as a bone. will only try to run when at lowest possible range on throttle.
any thoughts.
Phil

[Mac from NS]

Is it the same after it gets warm?
Do you use the chock when it is cold ?
Do you shut the gas off when not in use?

One of mine wants the chock and the other does't want
any at all and if i do I would have the same
problem as you.

[Phillip W. Lenke]

when warm will start up but does not start well . Like I said runs excellent when it starts

[Clem]

you said that it floods easy? How's the timing? When you shut it off do you run the gas out of the carb 1st? You may have a stuck float. On one of mine I have to pull the choke wait about 10 seconds and then pull the starter that is because after each use I run the gas out of the carb.

[Clem]

"will only try to run when at lowest possible range on throttle. "

this is the key to your cubs starting problems. I think the answer is in your carb.

[gitractorman]

One thing to keep in mind, here in the states the fuel companies switch gasoline blends for summer and winter. Summer fuel has a higher vapor pressure, so that it does not "evaporate" as easily. Winter fuel has a lower vapor pressure so that it "evaporates" easier.

What does this mean when running a cub? Well, now it is down in the 30s at night (at least in the northern 1/2 of the states), and highs only in the 50s/60s during the daytime. If you store your cub in an unheated area, and you still have a tank of "summer" fuel in it, the carburetor/engine will have a harder time atomizing the fuel, because the temperature is lower. Gasoline, as a liquid, does not burn very well. The vapors from gasoline, or atmoized gasoline (as in an IC engine) burns instantaneously, therefore, summer blend gas can "act" like water in your engine. Don't get me wrong, engines will still burn the fuel, but if your engine is not tuned properly, or if there is something else wrong, this may help complicate the matter.

Gasoline also seem to go bad much easier now than ever before. I have gotten in the habit of putting Stabil in each of my gas cans when I go to fill them up at the station. That way if I don't get around to using a can, or maybe I top off the Cub and don't run it for a few months, the fuel will still be good. I know that I have gotten other people's mowers in to work on, because they could not start them, and usually all I need to do is empty the tank and fuel system and put fresh gas in it.

The chemistry and terms I have mentioned above may not be exactly correct, but I tried to make this simple for everyone and you get the idea. This also may or may not be a factor in how your cub is running, but it is worth mentioning.

[Eugene]

will only try to run when at lowest possible range on throttle. Phil

Phil. Does the quote mean that the Cub will not rev up? Or the Cub will only start with the throttle set in its lowest throttle position.? What ignition system? Battery or magneto?

Couple of thoughts.

1) Carburation problem and/or to much choke when starting tractor.

2) Ignition problem. Timing to far avanced. No mechanical advance. Govenor problem.

3) Vacuum leaks.

Guess. You have more than one problem.

Eugene

[Phillip W. Lenke]

Runs fine idle and high after starting, Gary Dotson and George W. checked the timing real close to perfect, good spark, Where would the vacuum leak be . I am befuttled.
Phil

[Dave Irish]

Hi Guys I had the exact same problem in the summer. And I was baffled. She ran great once started but she was;nt hitting and fireing up as she should. After checking everything twice.I decided to change the plugs.

And bang fired up first hit....been great since.



Worth a shot. Dave

[John *.?-!.* cub owner]

Don't forget that leaks in the intake ( carb gasket or manifold gasket can cause starting problems, but run ok.

[Eugene]

John has the vacuum leak locations. Take an open unlit propane torch and pass over the manifold to block joints and the carburator to manifold gasket area - with the engine running. Also run the torch over the bottom of the manifold. If the engine speed up - leak.

As far as the timing. Check it any way. Things change. The rubbing block wears. Someone left the ignition switch on, without cranking the engine, and burnt the points. All of which will change the timing. With timing light you can check to see if the advance is working properly.

Do the easy checks first. This is going to be a process of elimination and correcting the fault or faults.

Eugene

[Phillip W. Lenke]

Thanks
I started it last night , still hard to start, I do have hot plugs in 21's, they seem to look like as Donny puts like a cookie crumb brown. So I feel this is OK. I did have excessive carbon before.
I will try the propane trick tonight and let you know.
Phil

[Clem]

another way to check for vacuums is spray a little wd30 on the manifold and other areas.

[John *.?-!.* cub owner]

I haven't checked it out myself, but it was posted on another site recently that the formula for wd40 has changed to make it less flammable, and it does not work as well for this type test.

[George Willer]

I haven't checked it out myself, but it was posted on another site recently that the formula for wd40 has changed to make it less flammable, and it does not work as well for this type test.

The propellant has been changed from propane to some kind of freon.