Cub won't start

Mon Apr 22, 2013 3:38 pm

I'm a new member on the forum.

I have a 48 Cub that belonged to my Grandfather, I've had since his passing in 1989.

It has always been very reliable, and I have been able to fix anything that came up until now.

I was plowing snow in March, and it just quit like the switch was cut off, after working on it for a couple hours it started but ran poorly, I tried to get it back to building but it died, and I towed it in.

I have cleaned sediment bowl, replaced in line filter, put new kit in carb.

Pulled plugs, checked compression (it's low , but when cranking there is good suction at carb)

I have cleaned points and checked gap (it's a magneto)

Many times I have pulled a plug and grounded, it has spark, also if I pull coil wire it has spark.

Sometimes it will "put" once or twice, and occasionally will run for maybe 10 seconds.

I have read that I can put a coil on and rewire the magneto to basically make it a "points" system, and I think that will be my next thing to try.

I'm operating on the idea now that something is wrong with either the magneto coil or the magneto itself.

I'm getting tired of chasing this problem,and need to mow grass.

Any thoughts ?

Thank you !


Re: Cub won't start

Mon Apr 22, 2013 5:01 pm

Have you double checked the timing? I know that she "died in flight," but the fact that you have spark, and she "phuts" on occasion suggests timing may be off.

What carb kit did you use? If you used the Tisco kit, that may have contributed to the problem.

Have you confirmed that you have good fuel flow through the carb? With the shutoff open, hold a can under the carb, remove the drain from the bottom of the carb bowl, and make sure there is good flow.

Did you clean the main jet?

Re: Cub won't start

Mon Apr 22, 2013 5:42 pm

Mike has some good things to check.

Are you sure you replaced the plug wires in the correct firing order after checking for spark to a ground?

You are getting spark, but are you getting it at the proper time when needed in the firing sequence?

Copper core plug wires are a must when operating a magneto.

Re: Cub won't start

Mon Apr 22, 2013 9:42 pm

G'day to you and I am glad that you are the keeper of the family Cub and have been for so long.

The problem you describe - been there ... done that ... a couple times and now when it happens it usually is for the same reason. I am betting that there was a bit of condensation happening, and water/moisture got into the cap - so there may be a bit of arcing/tracing in the cap. Probably the condenser is done too - it was for me. I cleaned my cap with WD-40 and replaced the condenser. Since then .. works nicely. I would be leaning toward that as the problem. The best solution if cleaning the cap with WD-40 works, then replace the cap.

Even though I am thinking moisture is what caused the problem .. a couple questions. You say you have spark. How bright is the spark. Should be a hot blue spark and not a yellowish spark. If it is yellow then you might have coil problems. If the is the case, new coils for the magneto are available and that is route I would counsel. You will have to reuse the core that is in your current magneto coil. It is pretty simple to replace. Are your plugs in good shape? How old are they? What are they? I recommend Champion D-21 as that is what has worked best for me, others use different plugs - depends on what works for you. And btw, when was the last time you did a complete tuneup? Have you ran SeaFoam through? 1/2 can in the gas and 1/2 can in the crankcase will help a lot with the valves and with compression.

Both Michael and Brian have made excellent suggestions as well. Check them all out.

We have lots of resources for our members, you may wish to take some time and follow the links below:

Image to :big smile: Forum Family. And you have come to the right place for all things Cub related. If you click on the Site Rules, Regulations, & Important Information, it will point you to :arrow: the Welcome Wagon wherein you will find links to many useful sites and topics. One of which is the Cub Manual Server. Enjoy!.

Re: Cub won't start

Thu Apr 25, 2013 6:25 am

First of all thanks to all who responded !

This forum is a great resource.

I tried WD40 inside the cap, wiped out, no help.

I removed magneto coil cover, there was corroson on contact, cleaned it up,no help.

I removed magneto coil, replaced with conventional coil , wired quickly with jumper wires,set points to .020

Bingo ! We have a running Cub !

A couple of observations that may help someone:

I see on the forum that no one likes the Tractor Supply carb kit, I had already installed mine before reading the forum, there is a mistake on the insructions for float measurement, hand written was 1 13/16" should be 1 13/32"

I also see that a in line fuel filter is not recommended, I had one on this tractor for probably 10 or more years, it worked fine, my thinking was the sediment bowl couldn't work as well as a modern filter. WRONG ! After my Cub quit, I cleaned the sediment bowl, which had caught some brown rust flakes, then I cut open the inline filter to see what it caught , NOTHING ! When I took Carb. apart , there was nothing in the inlet screen. So when I put it back together I left off the in line filter,sediment bowls work great.

I always cut off the fuel, and let the tractor run itself out, when I opened up the carb, there was no varnish, or scum in the bowl, this was after at least 22 years of service, I do not remember ever having the carb off, not sure when Grampa did.

A little more history, my Grampa worked for the local IH dealer, he bought my Cub after the first owner traded back in for larger tractor, mine is supposed to be either the first, or one of the first sold in this area. By Grampa working at the dealership, he was able to get attachments, an spare parts from time to time, these were passed on to me, which is a blessing when something fails !

I'm not trying to have a "show" tractor, but a nice working tractor, I keep the snow plow on the front, and a flail mower on the back, un hooking one or the other depending on the season. The un used attachmet is held up with a come along. I guess I'm lazy, but season change over takes about 3 minutes.

Grampa had another Cub with a sickle mower on it, and a home made wood cart, it is still over home, I use it to mow the field there,my Aunt now owns the home place.

Well, this is long enough, thanks again guys, if it's dry this evening, I 'll be mowing with the Cub !


Re: Cub won't start

Thu Apr 25, 2013 9:28 am

desoto wrote:I see on the forum that no one likes the Tractor Supply carb kit, I had already installed mine before reading the forum, there is a mistake on the insructions for float measurement, hand written was 1 13/16" should be 1 13/32"

Sounds like you are back in business, probably for a good long time before something else pops up.

On the TISCO carb kit, they are usually packaged with the wrong set of instructions. Any correct information is a coincidence.

Re: Cub won't start

Thu Apr 25, 2013 4:27 pm

Thanks for reporting back what the issue was. 22 years on a coil isn't too shabby at all. Glad you got it running. Enjoyed your story of your Cub .. and there is a 2nd one :?: :arrow: 8) too 8) .... so is it your Aunt's Cub or yours :?:

Jim makes a valid point. Humourous but bang on.... :roll:

Jim Becker wrote:Any correct information is a coincidence.

Re: Cub won't start

Thu Apr 25, 2013 5:47 pm

Hi desoto, yes, these Cub graybeards are good. They helped me get my '48 Cub started as well. Right now she's still running, just waiting for me to get time to rebuild and restore. She was a working tractor right up until ~3 years ago when my father-in-law went to assisted living. Unbelievable.

Re: Cub won't start

Fri Apr 26, 2013 5:58 am

I guess you could say the second Cub will be mine someday.

I bought my Cub from my Aunt after my Grandfather passed away, she said she would give to me, but I knew she could use the money, and didn't want any family problems.

My sister and I are now my Aunt's sole heirs, and I'm sure my sister is not interested in the Cub, that's why I say it will be mine someday, I'm already the only one who uses it to mow the home place.

Have a great day !


Re: Cub won't start

Fri Apr 26, 2013 6:04 am

I forgot to mention on previous post, started mowing last night with revived Cub and flail mower, Cub has more power than before, didn't have to baby in thick grass.

However, after about a 1/2 hour of mowing, pulley on flail mower came apart (spun out the center), now I need to fix it.

Wife said too much power !

Always something with the old stuff.


Re: Cub won't start

Fri Apr 26, 2013 6:39 am

desoto wrote:Always something with the old stuff.

New stuff has problems as well. And new stuff isn't likely to be around 65 years from now. Happy Cubbing!