'Surging' just started, troubleshooting advise.

[Lurker Carl]

3/8", that's the one. I'm always grabbing the 7/16" first, then making 2 trips. You'd think I'd learn by now!

[Buzzard Wing]

Yep Don I am thinking you are right on draining the gas. You probably know how 'scared' of ethanol blends I am in a vented tank. Especially this close to the water and our humidity. And a tank that is never going to be full.

As for the jet, that will be an easy one Carl.... Don may remember the 'original' jet from this carb... I sent it to Rick for use in his dyno testing and replaced it with a new one from TM. Would have been cheaper to buy one of his new ones with the time and money I have in this carb!


This Cub came with the 'lunch box' size tool box, so won't be a problem to give her a 3/8" wrench of her own!

[Buzzard Wing]

Oh and Gilles, that is the side of the house, I already have a picture of a Cub in front of the house.... Figured this one wasn't dressed for the main gate!
http://s2.photobucket.com/albums/y40/Bu ... 8Small.jpg

[Lurker Carl]

I like that tool box better than the tobacco tin that IH provided. Who sez size doesn't matter?

Don't worry about the alcohol attracting water into the gasoline. Condensation is gonna be your biggest concern, so keep the gas tanks very full or very empty and protected from large daily temperature swings.

I have a $1,000,000 carburetor of my own. I put WAY too much time and effort in a set of junk castings, a lesson in futility. That jet you removed looks like a pipeline compared to the replacement!

[Bus Driver]

If one suspects water in the gas, the first place to look is in the sediment bowl. Empty that bowl, several times may be necessary. For additives to deal with water, never use the methanol. Those sell for about a buck a bottle. Use Isopropyl, sells for about 2 bucks a bottle. The back of the bottle tells the type. Don't use rubbing alcohol because it already has all the water added that it can absorb. My last case of water in the Cub is a mystery. Could not have been rain. I did not believe it to be vandalism, but the volume could not have come so quickly from condensate. It was about a quart. And I was on a "road trip". The thing stopped several times for sediment bowl and carburetor draining along the way. Never happened again.

[Buzzard Wing]

Thank Driver... Good advise, I never use the 'cheap' dry gas.

Drained the tank, checked the main jet (clean) and put a 3/8 - 7/16 wrench and a stripped piece of data cable wire in a plastic bag in the the lunchbox. Also mounted a SMV sign to the rear rockshaft... gotta be legal!

I put about a gallon in with StaBil and it seems to have done the trick. Went for a short spin and it is running good again.

Got to love PO's that kept the Cub under cover.... what a difference between this 49 and the 64 Lo Boy. Look at the toolbox and light from the 64...
http://s2.photobucket.com/albums/y40/Bu ... 7Small.jpg

Thanks again for the great advise!

[Don McCombs]

Larry,

Believe it or not, I have come across several more of those "big hole" jets since we discovered yours. If you look down in that big hole, you will find a normal size orifice down there. Who knew

[Lurker Carl]

I guess the final design all depends on the particular supplier. I'm sure there were many considering 30+ years of Cub production with another 30+ years of post production parts providers. Bound to be some unique pieces that still meet the spec and get 'r done.

[Buzzard Wing]

Dang $23 down the drain! But it least it went to a good home, so I guess all is not lost.

[Buzzard Wing]

Finally got around to this one again and it is consistently 'acting up'.

It runs fine with about 1/2 choke. Seemed like a an air leak to a friend of mine (the old spray carb cleaner trick) but tonight I pulled the carb and slapped some gasket sealer on the throat gasket and it's still the same.

What I don't get is why it would run fine and suddenly not. That would seem to rule out the governor, mixture screw, replacement main jet, etc. Or should I tinker with the governor adjustments like GW said a month ago??? Could it be that 'warming' it up after who knows how long since it was used would make a difference??

My next step would be to adjust the governor or swap carbs with Cathy. What little sense I have tells me it's the fuel/air mixture (carb). I did adjust the idle air screw and it made no difference.

I'm just too stubborn to run it with 1/2 choke, that's like giving up.

[Gary Dotson]

I'd try the carb swap with Cathy. Never can tell, they might both run ok, or you might move the problem to Cathy. Either way, it's a good diagnostic step.

[Bus Driver]

"What I don't get is why it would run fine and suddenly not." A bit of debris moves into the smallest hole in the high speed jet.

[Buzzard Wing]

Instead of swapping the carb, I swapped the main jet.... and it runs great again.

The only weird thing is that the new jet that was in nameless won't fit in the other carb. I took the dial cal to it and there is only a few thousandths difference (the new one is 1/4" and the other, good one, is just under). Strange cause it is an IH part.

There was some stuff that looked like fine sand (magnet got none of it) in the bowl so I cleaned that out. Ran a 24 ga wire through the new jet and put it back in.... still needs 1/2 choke to run.

So I guess the answer may be that I should have gotten the larger orifice main jet?? I forget which one I ordered.

At any rate I am glad to have it run right.

Thanks again for the tips and encouragement!

[Don McCombs]

Strange. There's only .002 difference between the two jets. I wouldn't think that would be enough to cause you to need to run at half choke.