Fri Jul 12, 2013 5:08 am
It's actually harder for a spark to jump the plug gap the higher the compression, but it is almost impossible to start an engine with low compression, unless you pull it off. I definitely agree you should now look elsewhere for the problem, sounds like your mag and timing are spot on. Check compression, dry then wet, if that's good we have to move on to the fuel. However, it wouldn't hurt to re-check the wires are in the correct firing order, connected to the correct cylinders, that is the last thing that could be wrong in the ignition.....cylinders are 1,2,3,4 starting from radiator, dist cap should have wires in 1,3,4,2, clockwise as viewed from the operator seat.
Sat Jul 13, 2013 1:24 am
i believe my engine needs new rings or theyre all stuck my readings were all about 40 dry and they went up considerably when i squirted oil down the cylinders. but i also read that using a hand crank will give you low readings so i might put it in gear and pull it few feet so the engine will spin quicker. although i dont see the readings getting that much better. i guess i'm going to start looking into new bearings rings and such. thanks for all the help
Sat Jul 13, 2013 6:17 am
Before you tear it down, it is normal for a Cub that has been sitting up to have "stuck" rings. SOmetimes, not always, running it a few hours with Seafoam will do wonders for it. If it were mine, I would either get the starter working and jump it off, or I would carefully pull it off and get it running. IF your carburetor is working well enough to keep it running, then here is my treatment. Remove the inlet hose from the air breather, put some Seafoam into a squirt bottle like cleaner comes in. Squirt Seafoam into the throat of the carburetor until it starts to kill the engine, then stop and let the engine return to normal speed (1/2 open throttle or so during this treatment). Repeat this 5 times, on the 5th time, keep squirting until the engine dies. Let engine sit for 30 minutes, then restart. At that point, put 1/2 can Seafoam in gas, 1/2 can in oil, and find a way to work the Cub (plowing, pulling a weight, mowing heavy grass, etc.). After that see if the engine is good enough , or still requires rebuild, ANd expect a shower of carbon soot during this whole process, along with white smoke from exhaust.
Mon Jul 15, 2013 1:28 am
i bought a can of seafoam today and as soon as i get a helper i'm going to try to pull start the tractor, hopfully she'll start. i gently tugged the tractor about 3 feet per cylinder in 3rd gear with a forklift to redo the compression test and the numbers were at 100 or over on each cylinder. that probably wasnt advised i took it easy though. so i figure it should start if i pop the clutch. so hopefully the seafoam will work its magic
Fri Jul 26, 2013 1:15 am
well we tried to pull start it today and we didn't even get one fire. i just dont understand i had it firing at one point after i adjusted the valves and sort of cleaned the carbon at the valves. i wasnt thinking at the time cause i hooked 2 of the wires on the wrong cylinders and got the fire but no start and didnt check hard enough for that and assumed it must have been a timing issue and fooled around with that and now nothing. im certain it's timed correctly. is it possible maybe some carbon dislodged and is preventing the valves from sealing ? again thanks for the help hopefully this will get figured out!
Fri Jul 26, 2013 5:17 am
I know how frustrating this situation can be, because I've been there myself. It is very possible carbon has dislodged, but I still think you'd get some signs of life when pull starting. I hate to say it, but no fire at all tells me we still have an ignition issue. I would quickly check the point gap and run a piece of brown kraft paper (shopping bag) through them to clean them. Some of the weather around here might have caused the points to glaze or corrode, or even some moisture in the cap. While you're at it, with the freshest brain you can muster, confirm the wires are in the right firing order. I'm gonna believe timing is probably static timed correctly, since I feel like you've been there several times, but if still no start, you have to confirm that again also.
Now just one more thing, if you are getting nowhere, spray some starting fluid in the carb as you try a pull start, see if you get a chug. And one last question, and pardon me for asking, but I've done this more than one time, are you sure the gas was turned on last night?
Fri Jul 26, 2013 5:34 am
Its like reading a good mystery...I'm looking forward to the next installment and when you get it running as I know you will....You've gotten some great advice and from your posts it shows your no amateur yourself....Were all cheering for you....Patience and shuffle the cards....
Fri Jul 26, 2013 6:20 am
Pull the air cleaner tube connection from the inlet of the carb. Shoot a little starting fluid in there while someone pulls the starter rod. If the engine does not start while cranking over using the starting fluid, you've got an ignition problem. If it fires up and runs on the starting fluid, you've got a fuel delivery problem. However with the 40 lbs. of compression you mentioned, I don't know if it will ever run until you freshen up the motor.
Fri Jul 26, 2013 8:40 am
It has to be either timing, firing order, or no fuel. He seems to be getting good spark.
since the electric starter is dead.
He used a hand crank to get the 40 something psi compression readings.
1990caprice wrote:i gently tugged the tractor about 3 feet per cylinder in 3rd gear with a forklift to redo the compression test and the numbers were at 100 or over on each cylinder
ricky racer wrote:Pull the air cleaner tube connection from the inlet of the carb. Shoot a little starting fluid in there while someone pulls the starter rod. If the engine does not start while cranking over using the starting fluid, you've got an ignition problem. If it fires up and runs on the starting fluid, you've got a fuel delivery problem
Like Ricky said (as long as he can spin the engine fast enough) that will definitely tell him where to look.
pickerandsinger wrote:Its like reading a good mystery...I'm looking forward to the next installment and when you get it running as I know you will....You've gotten some great advice and from your posts it shows your no amateur yourself....Were all cheering for you....Patience and shuffle the cards....
Keep us informed on the progress, it's become intriguing!
Wed Jul 31, 2013 12:14 am
i havent forgotten yall, i have just been busy. i somehow must still have have an ignition or timing issue hahah probably both. while tugging the tractor around last week we had been spraying starting fluid in the intake of the carbureator also carb cleaner spray and nothing. it was getting gas you could smell it coming out of the exhaust pipe. today i had a few moments and checked in the distributor cap and cleaned the points with a strip of paper bag but didnt attempt to start it. is there a way the rotor could be 180 degrees off with the timing marks lined up? maybe something needs to spin around one more time? it fired before i had the bright idea of taking the rotor off. thanks again for everyones encouragment patience and help
Wed Jul 31, 2013 6:05 am
Bypass the ignition switch and see if that does it. I had one go bad once and beat my head against the wall trying to figure out what was the problem.
Wed Jul 31, 2013 6:08 am
Yes, rotor could be off by 180, since there are two symmetrical drive lugs on the mag drive. A quick refresh on magneto timing: get the rotor to pinion correct using the cast line on the rotor to the cast triangle or dot on the pinion. Then set engine to TDC on cylinder 1, closest to radiator. Then insure that governor drive lugs line up at 2 and 8 o'clock. Then, with rotor pointing to number one cylinder tower on cap, install mag. snug down loosely, roll it into the engine block as far as will go. turn engine over 1 complete revolution until timing mark on pulley lines up with pointer on front cover. Roll mag away from engine, slowly, just until impulse coupling snaps. Finish tightening magneto down at that point, and you are static timed enough to start a Cub, unless there is a second problem.
If ANY of the above is not correct, or cannot be performed as stated, get back to us with a picture or very clear explanation. If Cub still will not start, check spark quality, should be bluish white in color, not yellow. Otherwise your issue is with fuel.
Sat Aug 03, 2013 1:37 pm
i retimed it twice today. and still no luck once i have it running i should be a pro at static timing. i tried to see if i could spin the drive lug around so the other would be on top. it seemed like only one lug would ever allow the rotor pinion's mark line up with the rotors raised line. the spark is nice and blue. i have read you should use the copper cored ignition wires i have a set but they are not the exact length as the originals are supposed to be they measure 20" 19" 18" 16.5" i don't see how an inch here or there could matter all that much. installed right now i have a set that i bought before i found out you should use copper cored wires and they are the fiber wires but they do carry a spark and i cut them to the 17" 14.5" 15" 17" inch lengths. should i buy a new univeral set that are copper cored and cut them to the respective lengths? maybe the few inches on the first set i described messed up the firing order. oh and to what rickyracer said if the ignition switch was broken wouldn't i not get spark? thanks again everyone
Sun Aug 04, 2013 9:27 pm
Copper wires are better for a magneto; but I don't think that is the cause for your no start. Also, an extra inch of wire in either direction will make no difference, so long as the wire reaches the plug. You are correct that the rotor and pinion only line up at one spot in the rotation, but there is something in your discussion that gives me pause. Once you have the rotor and pinion lined up, forget that part. What is important then is that when you install the mag into the engine, the rotor is pointing near number one spark tower; I honestly don't know at that point where the rotor and pinion marks are, doesn't matter. I can more than imagine how frustrating this is, because I have been there myself. I have to believe at this point that you also have it static timed correctly, but if there is any question, please ask. If not timing, then you need to look at fuel next. I assume you are trying to hand crank, based on previous posts. If this tractor hasn't run in a while, you may have to pull it off to get it going, then the hand crank will likely work after the bugs are out.
Fri Aug 16, 2013 12:32 am
i am starting to think its the carb not tuned appropriatly only for a few minutes this evening i nudged the addjustment screw and maybe 3 times in 5 minutes of relentlessly ripping up the hand crank it almost fired up. but it sure wore me out i need to try to pull start it again and fool with the carbureator i figure so hopefully this ole cub will be running again. again thanks for all the encouragment and help!
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