My cub became a bit hard to start last fall requireing a lot of choking. I started it about two weeks ago after having sat since November but had to cover the intake with my hand to start it. I removed the brass nut on the side of the carb and everything there seemed ok. I removed the air inlet and the choke is working ok. Today it would not start not even fire once in a while. I had choked it enough fuel was dripping out of the carb. I removed the coil wire and the spark looked strong. I removed the cap and it was clean and dry. I could see no cracks. My knowledge is such that if I work on it , it will never run again. I knew sooner or later it would get me. Where to next? Any suggestions?
Not starting
- Thread starter v w
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staninlowerAL
501 Club
Hard starting with the presence of a good spark (is it good at the plugs?) is a symptom of poor suction thus your attempts to "help" this by extra measures of choking. I would suggest that you do a complete tune up and start with adjusting the valve clearance (if needed) then do a compression test wet and dry to determine what kind of vacuum your engine has to pull the fuel into the cylinders. If the vacuum is weak (less than 90-95 per cylinder) after adjusting the valves your're likely to have to remove the head and check the valve seating and condition of the valves. JMHO Stan
Dale Finch
501 Club
Did you pull a plug to see if you have spark there?
If not it's something between the coil and the spark plugs.
If you do have strong spark at the plug then perhaps something like timing, valves, etc.
I'm sure someone with more knowledge will have some suggestions!
If not it's something between the coil and the spark plugs.
If you do have strong spark at the plug then perhaps something like timing, valves, etc.
I'm sure someone with more knowledge will have some suggestions!
coppersmythe
501 Club
Gasket bad and or loose connection between the carb and intake/exhaust manifold ? Stan has a good place to look .....coppersmythe.................
staninlowerAL
501 Club
How did the engine sound when it was running? Any unusual skips, pops, etc or did it run smooth? It's possible for the engine to run on 3 cylinders and there's multiple causes of that. The compression test will determine if you have any stuck valves so look for that. I once had a 52 FCub that the engine would have a valve stick open if it sat for a while without running the engine. I was usually able to reach through the spark plug hole with a small rod or dowel and with a small hammer tap on the vale head and the spring would pop it back into place. Usually required doing it several times to get it to work right. Another option if the compression is weak is try to pull start the tractor. Sometimes this will get it running where you can then diagnose problems. JMHO Stan
Board shortener Tom
Well-known member
It's no coincidence this thread showed up today. I am going to look into the non-running cause of Karla's loboy today. I'm sure the valves need adjustment. I heard them clattering last summer but didn't get to them in time. We have moved and her cub was DOA and had to be rolled off the truck. It was around 6 degrees F that morning and we've always kept it in a heated space. "Milly" was not happy. The comments here will help me find the cause. I always appreciate the knowledge here and the willingness to share it. 
So a couple things that are easy to check:
1) Dale is right, you need to check spark at the plug. I had a Super A that sometimes wouldn't start with nice spark at the coil but it wasn't making it through the distributor. Fix in that case was to wipe out the coil cover (magneto) with some WD40. I've seen condensation in the distributor cap cause the same problem.
2) Drain the fuel bowl/strainer and make sure it only has fuel in it. A little water through the carburetor will short out the spark plugs. To be sure remove each plug and heat it up to dry it.
1) Dale is right, you need to check spark at the plug. I had a Super A that sometimes wouldn't start with nice spark at the coil but it wasn't making it through the distributor. Fix in that case was to wipe out the coil cover (magneto) with some WD40. I've seen condensation in the distributor cap cause the same problem.
2) Drain the fuel bowl/strainer and make sure it only has fuel in it. A little water through the carburetor will short out the spark plugs. To be sure remove each plug and heat it up to dry it.
Dasitton
New member
. Same issue- ran great. Fuel - Air - Spark- compression all Cyl’s better than 90. Timing great- Checking Valve adj this weekend.- has less than 10 hours on it since I adj valves. When it was running it wouldn’t easily start with starter-hand crank on first turn…… keep a check on this talk track….. rebuilt carb (orig). Bought new….install. Flooding….. N
ricky racer
501 Club
Sorry to hear about your Cub issues Vern. I'd suggest a compression test to see if you may have a stuck valve. If you don't have a compression tester you can usually borrow on from a auto parts store.
If you're not in a hurry and can wait until warmer weather and haven't got it going by then, maybe I could ride my motorcycle up there and we could put our heads together and figure it out.
If you're not in a hurry and can wait until warmer weather and haven't got it going by then, maybe I could ride my motorcycle up there and we could put our heads together and figure it out.
Dasitton
New member
Plugs had less than 10 hours on them- 3 were bad. Go figure. Had fire to the plug head- after reading the thread decided to check. Thank you
Thanks Rick. It gives a good feeling to know that you would do this. I was able to get my wifes help today so went to see if I was getting spark thru the distributer. Placed a heavy braided wire in a spark plug hole and had my wife roll the engine over. I wish the wire manfacturer had used a bit more coating. Put on a pair of gloves and tried again to prove what by now I knew. Spark was getting thru the dist. Decided one more time to start. Only after I poured a small amount of gas down the air intake did it fire. Within just a couple seconds I had to take the choke off because the engine was dying. Decided to put the mule drive back on for the mott. I had to buy a new pully for it. I left the cub running while I got the mower together and went to mow asparaguus fern. Ran like a champ and appeared to have its normal power. Mowed some of the outback. Quit because I wasn't sure how much gas was in it. I have a niece whose son wrenches farm equipment and who has recently become interested in cubs. He might even be reading this. If I have more trouble I may try to twist an arm. I know he was rebuilding my late brother-in-laws cub and I have a few things here that now belong to my sister. I will look at things everyone suggested except tear down. That's beyond me. Thanks everyone! Vern
Hi,
To test the power of the spark the Battery Ignition unit is making, you just use the spark plug wires that are there on the engine. Don't use another kind of wire that you might get shocked through.
Below is info for doing a spark test.
Be sure the Cub doesn't roll while doing the spark test.
Remove the spark plug wire from the center post on the distributor cap, and hold the wire by the insulation, with the metal end about 1/4" from bare metal of the engine block.
Be sure the transmission is in neutral, turn the ignition switch to on, and run the starter.
The spark should jump the 1/4" gap, and be blue or white. A yellow spark is weak, and needs improving.
The engine may not run, or run right, with a yellow spark.
Do the test in a building, or not in bright light, so you can see the spark well.
The battery should be fully charged for the spark test. Charge the battery if necessary.
A low output charger is better, it may take several hours to charge it.
If the spark is weak, or no spark, the ignition points may have corroded when the Cub was sitting.
The points may need filing or replacing. Wipe off all filings with a clean rag.
The points need the right gap to work right.
If you mean you poured gas down the air cleaner pipe, above the hood, that would overfill the air cleaner oil cup, at the bottom of the air cleaner, and would thin the oil in the oil cup.
I would remove the oil cup and clean it, and fill it up to the line with new light motor oil.
If the oil in the cup was too thick, that can make the engine start harder than it should.
I have been suggesting the gas ( more ethonal and the water it attracts) can be an issue with hard starts. I do not have an easy affordable option for ethanol-free gas in my area. I use Stabil 360 marine to treat the ethonal and stabilize the gas. I think this is an issue, especially if the tractor has been sitting for some time. I would try some fresh gas ( fresh from the pump, not the can) first since you have good spark.
staninlowerAL
501 Club
Ethanol free is available where I am for a little more cost at the pump and I'm pretty sure aviation fuel is non ethanol but it's cost prohibitive for me. Stabilizer helps also. I try to not let it sit in the can/tank for more than a month. I go so far as to remove any fuel from the tank if it's been sitting for a while and replace it with fresh fuel JMHO Stan
It also collects a lot of water.
Running good. No idea why it was better after checking spark but the air cleaner definetaly needed cleaning. 
The "oil" was indeed rather thin, the center cup was however more like sludge. Got it cleaned and back to work mowing. Will run for a few hours and try again.
This has been an interesting conversation. Several ccomments on the use of ethanol fuels but I use it and will probably continue. Aviation fuel as far as I know does not contain ethanol but would have a much lower vapor pressure which might make for hard starting. I don't really use the cub a lot but those quickie 15 minute jobs do add up. In a couple of weeks it will be time to start the 404 which has also sat all winter. It did however have all new filters last summer.
Thanks to everyone. I also promised the cub I would try to do better!
Vern
The "oil" was indeed rather thin, the center cup was however more like sludge. Got it cleaned and back to work mowing. Will run for a few hours and try again.This has been an interesting conversation. Several ccomments on the use of ethanol fuels but I use it and will probably continue. Aviation fuel as far as I know does not contain ethanol but would have a much lower vapor pressure which might make for hard starting. I don't really use the cub a lot but those quickie 15 minute jobs do add up. In a couple of weeks it will be time to start the 404 which has also sat all winter. It did however have all new filters last summer.
Thanks to everyone. I also promised the cub I would try to do better!
Vern