cub starting problem

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rohrski
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cub starting problem

Postby rohrski » Fri Apr 07, 2017 9:34 am

Hello all, I am having a starting problem with the cub as soon as it fires the starter kicks out, I have had this problem before do you think it is a mag problem? how can I test it? it does the same thing when it is hot I have to catch it in gear to get it started.

:thanx: in advance
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Mike in Louisiana
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Re: cub starting problem

Postby Mike in Louisiana » Fri Apr 07, 2017 10:18 am

Sounds like the starter bendix is bad.
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Re: cub starting problem

Postby Eugene » Fri Apr 07, 2017 10:33 am

Timing light, check spark/timing while cranking over engine.

Do you hear the magneto's impulse coupling click when hand cranking the engine?

Does "catch it in gear" mean towing the tractor or rolling the tractor to start the engine?
I have an excuse. CRS.

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Re: cub starting problem

Postby John *.?-!.* cub owner » Fri Apr 07, 2017 5:24 pm

Since you mentioned magneto, there is a good possibility the coil is getting just a little weak. I have run into that a couple times with mags. A weak impulse spring will also cause it, but the coil is the primary culprit from what I have seen. With a distributor the problems tend to be more varied when you have that problem.
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Re: cub starting problem

Postby Glen » Fri Apr 07, 2017 7:15 pm

Hi,
The Cub might need a tune up too, the points get burned, then it won't start well.
The condenser, distributor cap, rotor, the spark plug wires, and spark plugs all have to be good, or it won't start well too.
The timing is important too, like they said above.
The coil could be putting out a weak spark, it is common on Cubs, especially if it has never been replaced.
To test the spark, remove the coil wire from the magneto cap, and hold it by the insulated part of the wire, with the metal end of the wire about 1/4 inch from bare metal on the engine, turn the ignition switch on, then turn it with the starter and see what the spark looks like. It should be a blue spark. The guys have said that an orange spark is weak.
Here are pages from the Cub owner's manual showing how to replace the points.
NAPA has points for Cubs, they are number CS1600.
The NAPA condenser is an IH 200. TM Tractor has them also.
Below is a listing at TM Tractor for a new magneto coil, if you want to see what it looks like. :)

http://farmallcub.com/rudi_cub/www.clea ... e%2030.jpg

http://farmallcub.com/rudi_cub/www.clea ... e%2031.jpg

http://www.tmtractor.com/new/el/713fp.htm

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rohrski
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Re: cub starting problem

Postby rohrski » Sat Apr 08, 2017 4:39 pm

I have tuned it up with points, condenser, plugs and wires, rebuilt the starter, I checked the spark this morning it looks like there is plenty of spark, I never thought about adjusting the time, I was always told put it on tdc on the compression stroke with the distributor turned towards the motor then rotate backwards, when it throws it is in time, how do you check the cub with a light? where is the best place to get a coil? when it gets hot it is worse, I've always heard that could be a coil problem. Yes it will start if you catch it in gear.
Thanks again
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Re: cub starting problem

Postby Glen » Sat Apr 08, 2017 5:14 pm

Hi,
I'm not sure if you have a magneto, or Battery Ignition Unit.
You can check either system with a timing light. If it is a 12 volt timing light, it works better to get a 12 volt battery to power it. The other wire hooks onto the number 1 spark plug wire.
The timing pointer is on the left side of the engine front cover, and there is a mark on the front pulley.
Here is a page from the Cub service manual showing the marks. A 1949 Cub probably has 1 mark, number 1 in the pic, they did not have 2 marks until later.
Run the engine at slow idle speed, and point the timing light at the mark, and see where the mark is, then we will know.
TM Tractor is probably a good place to buy a coil, I posted their listing above, but if you have a Battery Ignition Unit, it is a different coil. :)

http://www.farmallcub.info/manuals/gss- ... 001-43.jpg

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rohrski
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Re: cub starting problem

Postby rohrski » Sat Apr 08, 2017 6:16 pm

Glen wrote:Hi,
I'm not sure if you have a magneto, or Battery Ignition Unit.
You can check either system with a timing light. If it is a 12 volt timing light, it works better to get a 12 volt battery to power it. The other wire hooks onto the number 1 spark plug wire.
The timing pointer is on the left side of the engine front cover, and there is a mark on the front pulley.
Here is a page from the Cub service manual showing the marks. A 1949 Cub probably has 1 mark, number 1 in the pic, they did not have 2 marks until later.
Run the engine at slow idle speed, and point the timing light at the mark, and see where the mark is, then we will know.
TM Tractor is probably a good place to buy a coil, I posted their listing above, but if you have a Battery Ignition Unit, it is a different coil. :)

http://www.farmallcub.info/manuals/gss- ... 001-43.jpg

Hi, yes it is a Magneto I will put the light on it and see. thanks
Cub owner for the last 20 years, such a well engineered piece of equipment.
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rohrski
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Re: cub starting problem

Postby rohrski » Sun Apr 09, 2017 11:11 am

Put the light on this morning, it was about a inch before tdc I moved it to tdc and it started good, I tried mowing with it and it started to miss I don't know if that's because of moving the dist or bad gas, it has sat all winter I put fresh gas in it and will run it to see how it does. maybe get a new coil

:thanx:

:tractor:
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Re: cub starting problem

Postby Jim Becker » Sun Apr 09, 2017 1:16 pm

rohrski wrote:Put the light on this morning, it was about a inch before tdc I moved it to tdc . . .

Was this observed while cranking the engine with the impulse clicking or with the engine running and the impulse disengaged? If the impulse was clicking, at TDC is correct. If the engine was running, the mark should be about 1/2 to 5/8 inch before TDC.

You had too much advance before, but may not have enough now.

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Re: cub starting problem

Postby staninlowerAL » Sun Apr 09, 2017 2:11 pm

The last time I checked McDonald Carb had the J4 mag coil for about $75 plus shipping.

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Glen
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Re: cub starting problem

Postby Glen » Sun Apr 09, 2017 5:55 pm

Hi,
Maybe I wasn't very clear above, I thought if you checked the timing with the timing light, we would know where it is set. I wasn't too clear about where to set it. It should be like Jim B. said above, before TDC the amount Jim said, when the engine is running. :)

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rohrski
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Location: West Virginia

Re: cub starting problem

Postby rohrski » Sun Apr 09, 2017 6:50 pm

OK that was running so I will have to turn it back some, I will redo that. thanks again
Cub owner for the last 20 years, such a well engineered piece of equipment.
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