'48 cub surging

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ferret_airlift
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Zip Code: 49251

'48 cub surging

Postby ferret_airlift » Wed May 10, 2017 7:07 pm

So, my '48 cub is surging, and searching around I found that
A: I should check the main jet and
B: I appear to have the Zenith carb.

My question is, where is the main jet on the Zenith carb? I haven't found a good picture of it that shows

Thanks in advance

staninlowerAL
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Re: '48 cub surging

Postby staninlowerAL » Wed May 10, 2017 7:16 pm

You might try a search for Don McCombs posts. I believe he or Dale Finch posted a parts schematic some time ago. If you don't find one send me a PM and I'll dig through my info and see if I can find one. EDIT: Found this one, maybe it will help:
Zeneth Page-02-10.jpg
Last edited by staninlowerAL on Wed May 10, 2017 7:23 pm, edited 1 time in total.

tst
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Re: '48 cub surging

Postby tst » Wed May 10, 2017 7:22 pm

the main is easy to get to with out taking the carb off, on the bottom of the bowl on the back side there is a 1/2" hex plug, take the plug off and the jet is inset about 1/2" in the hole, ck for fuel starvation, filter in the bowl and the filter in the carb, if they are good check governor adjustment

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pickerandsinger
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Re: '48 cub surging

Postby pickerandsinger » Thu May 11, 2017 4:24 am

Surging also could be governor linkage...I had that once and after adjusting it , it settled down...Dave....PS just read your post Tim and I see you suggested that also...Oh well two suggestions are better than one...hahah...Dave
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ferret_airlift
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Re: '48 cub surging

Postby ferret_airlift » Thu May 11, 2017 8:40 am

I found the plug, and I can see the jet, but I can't get it out. Is there a trick to it?

ferret_airlift
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Re: '48 cub surging

Postby ferret_airlift » Thu May 11, 2017 3:16 pm

What has to be done to adjust the governor linkage? It seems to move well enough

Crimson Tim
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Re: '48 cub surging

Postby Crimson Tim » Thu May 11, 2017 6:18 pm

ferret_airlift wrote:I found the plug, and I can see the jet, but I can't get it out. Is there a trick to it?


A flat bladed screw driver that is small enough to fit in there without boogering up the threads, but large enough to span across the back of the jet and fully engage the slot at each side. Some people have had to grind down a larger screwdriver to get a good fit.

ferret_airlift
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Re: '48 cub surging

Postby ferret_airlift » Thu May 11, 2017 6:36 pm

Cleaned the jet, and still having the issue. I think I'm going to rebuild the carb, just because and go from there. It hasn't had that since I've owned the machine

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Stanton
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Re: '48 cub surging

Postby Stanton » Fri May 12, 2017 7:43 am

Don't forget to look at your governor linkage. Refer to Service Manual GSS-1132 Fuel System found via the Quick Links, then PDF Manuals, then Service Manuals. Download manual for future reference.
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ferret_airlift
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Re: '48 cub surging

Postby ferret_airlift » Tue May 16, 2017 7:15 pm

Okay, so carb rebuild actually made the issue worse. I adjusted the governor linkage, and that's helped a lot. I think I need to adjust it just a little more and it will be good.

On a side note, there seems to be a little bit of play on the linkage. Is that normal, or should I tighten it up? It isn't much, probably around half an inch back and forth

Crimson Tim
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"George", 1958 LoBoy Cub with Wagner 45 Loader
"Ringo", 1977 Cub

So far, Paul and Ringo have arrived. John and George will follow in a few weeks.
Circle of Safety: Y

Re: '48 cub surging

Postby Crimson Tim » Tue May 16, 2017 11:11 pm

This is the linkage between the governor and the carb that you're talking about? I think consensus will be that it only takes a little play in that linkage to cause response issues like what you're having. Half an inch sounds like a lot.

Where is the play coming from? There is a keyed joint where the transverse shaft crosses behind the fan and attaches to the inboard side of the governor that often gets worn. People have used shims, JB Weld, actual weld, and all kinds of other things to address that joint. Occasionally, actual replacement parts!


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