9N stumbles when giving gas

[Abbby]

I have recently rebuilt carb and also plugs, wires, cap, rotor, and points in front mount. I had this issue before this and also still have it if not a little worse now. Whenever I give it more gas regardless if at idle or mid range the engine stumbles a little and then runs fine after that. When pulling under heavy load at contant throttle it runs great. Seems to me maybe the governor is to quick to react to my throttle change and the engine gets lean for short time. Have tried adjusting carb and does not affect this. thoughts?
 

[Den N Ms]

Abbby,Have you tried opening up the main jet needle ,say 1/2 turn or so?Tryed pulling the choke out 1/2 way?To see if it is starving for fuel.Or it could be worn distributor bushings causing the problem.
 

[Abbby]

tried opening up the main jet but did not seem to affect it. Maybe I will try more or just go with the holding the choke half open. Did check the dist bushing when I put points in. Was not perfect but sems it had a little wiggle in it.
 

[Den N Ms]

Abbby,Try the choke and see if that helps.If it doesn't I would blame the worn bushings causing point setting to misfire.
 

[GB in MT.]

Abbby;
You state....:"
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I have recently rebuilt carb and also plugs, wires, cap, rotor, and points in front mount. I had this issue before this and also still have it if not a little worse now. Whenever I give it more gas regardless if at idle or mid range the engine stumbles a little and then runs fine after that.
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After you do what Den said to check, and have reported back with the results.......try setting up the carb to your engine, using my way of setting it.!!!
If these settings do NOT help.......then I am leaning to what Den, said about the distrib shaft, having worn bushings.!!!!!

Try this then report back as to weather it helps any at all.


By you doing work on the two main things that can cause your problem....we/you now have to cypher out, what the problem really is before we can give you the help you need.!!?????

Gary
 

[russb wa]

I get that stumble on 8N and also geo metro
w/throttle body injection. The best carbs for not
having that characteristic are the slide type with
vacuum dampener, motorcycle type.

What happens with your N is, when the throttle is
opened suddenly the air fuel mix goes lean for a
moment, till the velocity of the air increases and
draws more fuel. Of course the engine has to
speed up for that to happen. It is somewhat the
nature of the beast, worse when cold. As you
describe it, doesn't sound like much more.

Cars used to have accelerator pumps that gave a
little squirt of gas when you stepped down on the
throttle. If you advance your throttle slower it
should help.
 

[souNdguy]

how do plugs look? ( white ashy? )

any popcorn popping from exhaust?
 

[Abbby]

OK. So set the carb precisely as described and still same problem. The problem is fixed if I hold the choke out. I know some will say carb needs cleaning but I just rebuilt carb and soaked for days in cleaner. carb was actually fairly clean when I started. Not sure if you remember but a while back I was the guy that discovereed my carb did not have a main jet in it but I installed the one in the kit during the rebuild. Seems to me the diagnosis suggets my engine wants more fuel then what the carb can supply right now.
 

[Hobo,NC]

[W_B]

[Abbby]

Did some more trouble shooting today. Back out the1 main jet and has basically no affect afetr a certain point. Plowed some snow and put a clothes pin behind the choke knob and the thing ran great. Seems to me the main jet is just too small. As stated earlier, I just rebuilt the carb and am fairly certain there was not a main jet in there. Not sure what I put in for jet sizes but put in what is reccomend on this site. Is it easier to drill mine out or just replace them? Any thoughts on what standard size is and what I should go to?
 

[Gregorius]

I had the same problem after rebuilding my 8n carb with a TSC kit. Thanks to this site I determined the jet sizes were wrong, and after drilling them out by hand with a pin vise mine runs great, starts right up in 20 deg weather with very little choke and it's still 6 volt!
 

[Abbby]

Do you remember what size drill bit you used for main jet? Did you also drill out idle jet?
 

[Gregorius]

Here is the info I used off of N tractor forum:
I go ahead and put the econ jet in there. So far, all of the carbs I have rebuilt were already threaded for the jet. If not, it's a simple matter to run a 8-32 tap in the econ hole. Jet sizes supplied in the kits seem to vary widely in hole size. There are various recommendations based on what works for different folks. I know these sizes work:
Idle jet at least 0.032"
Economizer Jet at least 0.046"
Power Jet at least 0.043"

Make sure the related passages are larger then the jet sizes listed above.
KL

Here is info from this forum:

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=nboard&th=712077