Sun Aug 18, 2013 5:36 pm
hello all, i am helping a friend bring a nice little cub back to life. no pix at the moment but will try to cobble some up.
this ole cub is a 48 we believe and from all outward signs is in pretty good shape. it came with the property and by all accounts may have been sitting for upwards of 10 years. outside in western oregon with the spark plugs removed. fortunately the motor is not froze and it turns over fine. my friend has drained the fuel and oil and replentished them with fresh stuff. i went over to see if we could bring it back to life. after a quick once over i checked for spark and got the big zilch. nothing not even right at the mag. now i understand the basics of magnetos and have since done a little reading on them in the manuals archive but dont have much hands on expeirience except for using some that worked.. so not knowing much about magnetos i did not go through my normal no spark checks. we did nt even take the cap off so it could be something simple but i would like to get the lowdown on how to check the mag to be sure it is not the problem especialy if there are any quick checks that should be done first. is it comon after years of sitting to end up with no spark?
next time we attack the cub we will be ready to dig a little deeper on the spark issue, hopefully with some suggested course of action from the experts here.
thanks for any an all suggestions
Sun Aug 18, 2013 5:57 pm
G'day to you and congrats to your chum on his inadvertent entry into the wonderful world of Cubs
As you might have already discovered there are lots of resources for our members and it is well worth exploring all of them in the links below:
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
the Welcome Wagon
wherein you will find links to many useful sites and topics. One of the most important resources are Owner's Manuals, Parts Catalogs and Service Manuals. The Cub Manual Server
is the home of the jpg versions and the PDF Manuals
-- well the pdf's of course
Magneto's are pretty simple critters - here is the parts breakdown for one:
Here are some topics that should be of help to you...
Hope this helps.
Sun Aug 18, 2013 6:19 pm
Compression tests - - first. Then ignition system.
Sun Aug 18, 2013 6:47 pm
Eugene is right, you may have stuck rings and/or valves that will never let the engine fire up. However, just a couple of quickies on the mag. First off, these J-4 magnetos are not exactly like most others, but they are quite simple. Since it has been sitting up, check the post on the outside; there should be a wire to a kill switch, make sure that is not grounded, as it will kill the spark. Second, it is very likely your points, if any good at all, have glazed over in time. You would need to remove the distributor cap, and then the top plate, to get to them. Cleaning them with brown paper will remove the glaze, you really should NOT use emery cloth or sandpaper. The rotor is timed to a pinion gear that will only go back on one way; those are both located under the brown bakelite cover, no need to remove that yet. Once you start tearing apart, you can get into timing issues. Let's assume this Cub once ran, with all settings as is, and the current problems are purely from lack of use....
Sun Aug 18, 2013 7:14 pm
If it has been setting for 10 years I do not think brown paper will help the points, A point file is only 2 or 3 bucks. You can file the points and they should make contact , be sure to prime the oil pump. To do this remove the oil filter top and filter, there will be a hole in the block behind the filter. Use a squirt can to squirt about a pint of oil in that hole. This will prime the pump. Do this before trying to start. take the plugs out and pump in about an oz of oil in all the cylinders, take the brass plug out of the side of the carburetor and run a small copper wire in the hole on the back side of the plug. This is the main jet. That should give you a starting point.
Sun Aug 18, 2013 7:49 pm
This is a points file and is a useful tool to have.Performance Tool Ignition Point File, Model# W123CPERFORMANCE TOOL IGNITION POINT FILE W123C
An emory board would do the same thing or a manicure kit nail file (yup - raid the bride's tool chest
Tue Aug 20, 2013 9:04 pm
i gotta disagree on the compression check. i may be new to magnetos but i am not wet behind the ears. i have wrenched professionally for over 10 years on autos. i have found when dealing with a no start first thing i personally like to check is fuel and spark. also i didnt want to bore you all with the boring stuff. i did my basic diagnostics found fuel probs ( working on those) found no spark. if it had been a distributor ( or computerized distributorless) i would have continued down the basic steps for those systems. mags are new to me and i didnt want to be chasing a ghost down a rabbit hole before i read up on magnetos. so while i was downloading and reading i just posted about my questions surrounding mags. i have read the suggested links, watched the timing video along with reading and watching many other magneto instructions. between the suggestions here and what i have read, the next time i get over to my buddies i will be able to continue the diagnostic inspection. also, just from listening to it crank i am pretty confident she has enough squeeze to at least cough. i had him do the oil in the holes before installing plugs and letting it soak a bit. when he put the juice to her she (much to my amazement) cranked right over.
on the fuel side of things. i checked out TM tractor parts for a carb replacement. i am encouraging my friend to just swap out the carb for now to get it running and then he can learn all about the carb this winter and when he gets it rebuilt he will have a fresh one waiting on the shelf should he ever need it. i couldnt find carbs from TM is there a simple source for rebuilt/new carbs for the cubs? or am i going to have to dig into this one to get it up and running.
this tractor will be put into regular service on a intensive veggi farm supplying farmers markets a farm stand and onsite restaurant, she wont just be yard art thats for sure.
thanks for the help and suggestions, i will let you know how it pans out but it could be a bit before i get back over to work on it.
Tue Aug 20, 2013 9:23 pm
Kenny, Steiner and McDonald Carburetor both have new aftermarket carbs. McDonald also sells rebuilt. However, for half or less the price of a new one, you could send it to be rebuilt and have it back almost as soon as ordering a new one. Oftentimes, a good cleaning and new body gasket are all that is needed.
Wed Aug 21, 2013 7:37 am
Kenny'z Garden wrote:i gotta disagree on the compression check. i may be new to magnetos but i am not wet behind the ears. i have wrenched professionally for over 10 years on autos. i have found when dealing with a no start first thing i personally like to check is fuel and spark.
Suggest, at least consider the advice offered by board members.
By all accounts may have been sitting for upwards of 10 years. outside in western oregon with the spark plugs removed.
Typically with this engine, if it's been sitting for a long time, usually find a stuck valve or two.
Prime the oil pump.
The carburetor is dirt simple. Good cleaning and perhaps a kit. Much cheaper than buying another carburetor.
Wed Aug 21, 2013 8:04 am
Kenny'z Garden wrote:just from listening to it crank i am pretty confident she has enough squeeze to at least cough. i had him do the oil in the holes before installing plugs and letting it soak a bit. when he put the juice to her she (much to my amazement) cranked right over.
You are right, she probably will at least cough and maybe even run real nice when you get some spark. Not to beat it to death but a compression check is a good way to tell the general condition of the engine, stuck valves, stuck or worn rings... Another thing to consider is low compression = low power. Hope you get 'er figured out and let us know what you find.
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