8N runs rough after warming up

Adam Brandt

New User
I have a 52 8N which I have been having an issue
with. Basically after running for longer than 10
minutes, when I change gears and use the clutch it
will act like it is going to die, and runs rough
for a few seconds and if I ease into gear slowly
it runs fine, but if I release the clutch fast it
dies. I replaced spark plugs, checked for spark
which is good, fuel flow seems to be fine,
replaced the coil - no difference. I am not sure
what else to check. The cap rotor and points are
all clean and look good. I am thinking of
replacing the spark plug wires, but they look good
so I dont think that is the issue. Any ideas?
 
(quoted from post at 19:43:00 03/04/13) I have a 52 8N which I have been having an issue
with. Basically after running for longer than 10
minutes, when I change gears and use the clutch it
will act like it is going to die, and runs rough
for a few seconds and if I ease into gear slowly
it runs fine, but if I release the clutch fast it
dies. I replaced spark plugs, checked for spark
which is good, fuel flow seems to be fine,
replaced the coil - no difference. I am not sure
what else to check. The cap rotor and points are
all clean and look good. I am thinking of
replacing the spark plug wires, but they look good
so I dont think that is the issue. Any ideas?

By dropping the clutch all the extra load is dumped onto the governor in a hurry driving the throttle plate open. Try opening up the high speed needle about a half turn. The engine will go lean for a second with that throttle plate wide open.

The N clutch should general be slipped into action.
 
Front mount point gap is .015 that's a long way from .125. Not sure if you can even get points that far apart.

Sparkplug gap is .025
 
I am new to the 8N carburetor. Which one is the high
speed needle? Also what is the best way to adjust
the gap of the points, should I use a spark plug
gapper?
 
Trouble shoot then parts not the other way around. You say spark looks good well make sure it is good as in Blue/white in color and will jump a 1/4 inch gap or more at all plug wires. Point gap on a side mount is 0.025 same as the plugs. Next when was the last time you serviced the air cleaner?? It could be full of water or ice and dirt. So does choking it help or hurt?? If it helps you may have a clogged main jet if it hurts go back to the air cleaner and or the main jet is to far open and it is running to rich but you should see black smoke if that is the case
 
Adam.......the M/S carb has 2-adjustment needles. The down-pointing mainjet is best set to 2-turns and LEAVE-ITT!!!

The side-pointing idlemix is adjusted for FASTEST idle, NOT SMOOTHEST idle. Understand the DIFFERENCE??? The behind the carb idle speed is adjusted for a SLOOOooow 400rpms. (ennythang under 500rpms is good)

The last time I adjusted the idle on my eazy starting 6-volt 52-8N, the idlemix screw was about 1/8-th turn. Remember, the side-pointing idlemix is BASSACKWARDS; out fer lean; IN fer ENRICH.

As for ignition points gap=0.025". A sparkie gap round wire can work iff'n yer careful. Remember to clean/polish the ignition points after installation and adjustment (0.025) Me? I use a clean $1-bill clamped between the points and pull. Iff'n yer really cheap, tear a strip from HEAVY brown paper grocery sack and use that.

As fer yer ruff-runnin' when warmed-up; yer weaksister ignition switch starts causing weak sparkies after about 15-mins. New switch, $15 (cheap) .........Dell, yer self-appointed sparkie-meister
 
AS per the manual front mount point gap is 0.015 which a 49 would be. This guy say he has a year that would be a side mount and again as per the manual the point gap is 0.025. If you have to set your points to what you said you have bigger problems like bad distributor bushings and you need to fix that
 
I would say the tractor running well is what is best - compensating by widening the gap does the job and just resets the distributor for its advance - actually the points will open wide more so than less.
 
So I have done the following to troubleshoot the issue. I removed the carburetor, fuel line, reservoir bowl and cleaned everything. The Carburetor was extremely clean - no gunk at all in it. The filters were a bit dirty. I also removed the air filter and hose assembly and ran the tractor without it, and it seemed to run great. I did notice after some time that in the clear fuel filter I have the gas would flow fine for the first few minutes, then it would drip into the filter. I dont think it is getting enough gas. Again, it will run for about 10-15 minutes then it will act like it is starving for fuel - I pull the choke out it will run for a few more seconds then dies. I have the fuel turned on all the way, so it should be getting fuel from the tank. I drained the tank and refilled it, when I drained the tank it didnt look like any large particles drained out with the gas into the collection container. I also replaced the spark plug wires with a new set of copper core ones as I did notice that a few were a bit cracked and when I ran my hand across one of them I could feel electrical shock. The ends of the spark plug wires that run into the distributor were quite dirty and 2 of them were split down the middle. When the tractor runs now it runs very well and has more power - but it will still die after 10 minutes of use. Any further ideas on what to check next?
 
After the 10 mins have you tried to see if the igintion switch is working? By using a jumper wire across your terminal block? if that didn't narrow it down I'd probably toss in a new condenser... As I don't know of a way to really test one of those...
 
[b:1f95247c02][i:1f95247c02]
Adam;
You say......:I did notice after some time that in the clear fuel filter I have the gas would flow fine for the first few minutes, then it would drip into the filter. I dont think it is getting enough gas. Again, it will run for about 10-15 minutes then it will act like it is starving for fuel - I pull the choke out it will run for a few more seconds then dies. I have the fuel turned on all the way, so it should be getting fuel from the tank. I drained the tank and refilled it, when I drained the tank it didnt look like any large particles drained out with the gas into the collection container. end quote!

You are right ......you do have a fuel restriction problem.!!!!
Could be in any filter, BUT my guess is......"running the fuel wide open" (which tells me that you are trying to run off the 'Reserve' section of the sed. bowl), and the reserve passage in the sed bowl is plugged up, not letting enough fuel get to the carb bowl, to run the engine!!!
Thus the 10-15 mins of run time you have stated.
MY ? would be/is.....How did you flush out/drain the tank.....through the sed bowl,...OR with the sed bowl out of the tank??????
Next.....Only open the fuel valve at the sed. bowl two full turns, then start the engine after waiting for the carb bowl to fill!!!
If that extends yer run time and or fixes yer problem,....then you have found your run-time problem........(Sed. bowl screens are plugged inside the tank!!!!!)

Just my WAG!!!!!!

Gary :roll: [/i:1f95247c02][/b:1f95247c02]
 

If you are using one of those after-market, in-line fuel filters, get rid of it. The next culprit that comes to mind is that it might be time to check the clearance gap on the valves.
 

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