48 8n that just wont start easy and run right

I just cant get this machine to run very well, or be very reliable to start. 8n front mount that i rebuilt the engine in over the winter. I just got it out this last weekend to move some brush with and it died when i was pulling a pretty good load. It would fire occasionally, but wouldnt keep running. It has great spark on every cylinder (1/4in jump). I let the gas run out the bowl for 30sec, no problem. I even took the dist off in the field and checked it on the bench. Here is how i have gotten this thing to run more times than not. If i take the intake pipe loose from the carb and put my hand over it and crank it 6-7 cranks, it will fire pretty well and usually start. It seems like it really needs some vacuum at the carb for it to start. It runs ok at just above an idle, but when its under a load it dogs out and has a hard time recovering. Im getting very frustrated with it and need some advise before something bad happens to this machine! (BFH or worse)Lol!!! Just kidding, i wouldnt beat on it after spending so much time rebuilding it. Any comments are appreciated.

" 8n front mount that i rebuilt "

Did the rebuild include a new/rebuilt carb?
50 Tips

Check the compression on it. If lower then 90PSI it has not been run long enough to break it in and that can cause you problems due to the low compression. It may need a good number of hours of run time to get things right.

DB454........check yer 4-nipple firing order;1,2,4,3 CCW. Many times nuebie mechanics swap sparkies 3&4. Theses N-Engines are soooooo goooood they will start and run on just 2-cyls but will not have enny power just as you complain. Report back ........Dell, yer self-appointed sparkie-meister

Whats your points gapped at?

vacumn leak maybe? and gas at bottom of carb just means fuel is getting to carb, it gives you no indication if gas is getting THROUGH carb.Every bit of gas the engine uses must pull through passages in bottom of bowl. Any rust or water in those passages and its dead.I got a little water in my 2n from a gas can,i bet not 1/4 teaspoon full in bottom of bowl.it wouldnt run at all.When i bought my latest a 48 just like yours ,it had set many years.The gasket between the bowl and and the upper body was dried out and not sealing,it would start with full choke but not run.Does it seem to be flooding?could be your air cleaner also is stopped up.And believe it or not when i first got my first 2n,it would run but not rev up, after many trials and tribulations ,i found a red grease rag lodged between the air cleaner,and the carb in the air tube. How it got there i have no clue,but the fellow i bought it from never could get it to run right, so it must have been before his time. another thing,has your been converted to 12volts?or is it 6v still.you could have a problem with the ignition resistor.

I did rebuild the carb when I did the engine rebuild. The points are gapped at .015. When I get off tonight I will check on the 3-4 spark plug.

check to make sure you have no leaks from the gasket between the carb and manifold, the trottle linkage and where the intake meets up with the block---you may also have a little trash in the carb. when it was having trouble, did you check the spark right then and there? or did you wait--important to check right when it happens since some electrical issues are caused from heat build up. if not just kick the snot out of it-it works for me some times.

youve got to cuss them in chinese nowdays,just to get all the new parts synced correctly!. I bought a dist cap the other day and had to take a grinder to it before it would even fit.cant complain too loud though,at least they still attempt to make parts.bought some from new holland last summer that were built in mexico.

Got home from work and tried a few of the suggestions from here. Firing order is correct, compression is 100# on every cylinder. Is there anything else I can check on it?

Venturi upside down or not sealing properly between carburetor body halves?



If everything else checks out okay - You may find yourself chasing a vacuum problem or lean condition.

Does fattening up the main jet make any difference in performance?

What heat range plugs are you running and what do they look like after working it for a half hour or so?

Old gas maybe?

Dollarbill, it has fresh gas and I'm running autolite 437's. The carb has plenty of suction, just seems like it needs a lot of choke or my hand over the intake to get it started. I have adjusted the jets according to the manual along with a few different combinations, but still cuts out and almost dies when quickly idled up. If I slowly add throttle, it does ok till RPM's get up there and then falls on its face.I sure wish somebody from here lived near Topeka Ks, I would give them some $ to give this thing a listen. Frustrated!

(quoted from post at 23:26:17 02/24/12) Dollarbill, it has fresh gas and I'm running autolite 437's. The carb has plenty of suction, just seems like it needs a lot of choke or my hand over the intake to get it started. I have adjusted the jets according to the manual along with a few different combinations, but still cuts out and almost dies when quickly idled up. If I slowly add throttle, it does ok till RPM's get up there and then falls on its face.I sure wish somebody from here lived near Topeka Ks, I would give them some $ to give this thing a listen. Frustrated!

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It sounds to me like there is blockage in the carb main fuel metering sysem. You say you redid he carb, but you may haave not got everything out of the passage ways. Very easy to miss something. At this point I thin k I would redo your carb rebuild and run a wire thru every paasage way after removing all of the jets. Also use a rubber tipped air nozzle to blow them out real good. Dan't assume everthing is clean, make sure! We all get to go back and redo things from time to time. We can get sidetracted by thnking that ," well I rebuilt the carb so it can't be that"
Good luck!

(quoted from post at 09:43:58 02/24/12)

(quoted from post at 23:26:17 02/24/12) Dollarbill, it has fresh gas and I'm running autolite 437's. The carb has plenty of suction, just seems like it needs a lot of choke or my hand over the intake to get it started. I have adjusted the jets according to the manual along with a few different combinations, but still cuts out and almost dies when quickly idled up. If I slowly add throttle, it does ok till RPM's get up there and then falls on its face.I sure wish somebody from here lived near Topeka Ks, I would give them some $ to give this thing a listen. Frustrated!

Click to expand...

It sounds to me like there is blockage in the carb main fuel metering sysem. You say you redid he carb, but you may haave not got everything out of the passage ways. Very easy to miss something. At this point I thin k I would redo your carb rebuild and run a wire thru every paasage way after removing all of the jets. Also use a rubber tipped air nozzle to blow them out real good. Dan't assume everthing is clean, make sure! We all get to go back and redo things from time to time. We can get sidetracted by thnking that ," well I rebuilt the carb so it can't be that"
Good luck!

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b:326b651b9d][i:326b651b9d]
Bob;
Ya beat me by about 5-10 mins. with yer reply!!!! :lol:
Here's a couple of things to help him get the carb "cleaned", and set up correctly, this time around!!!:
ALL passages in the carb need wired out:

After the carb is cleaned properly, and blowed out with the 80-90 lbs of air....then set yer carb up as instructed by this sheet:


GB [/i:326b651b9d][/b:326b651b9d]

DB, I do have a place out east of Topeka right off Stanley Road, but I won't be back until Memorial Day. Sorry! Charlie