UPDATE carb idle adjustment screw and question

Thu Jul 15, 2004 7:02 am

Ok thanks everyone and lurker carl your site was great!
Ok this is what I did and what I broke fixing things! :oops:

ok I had to go to tractor supply to get some seed and well I walked out with the TSC carb kit and as lurker carl said it has the wrong instructions but using his website I fixed up my carb.

What I found when I tore mine done.
1)gasket for bowls halves was closed shut for the idle circut (the part with the half moon shapped cut out of it) it was tight together there.
2)the float was well out of adjustment letting gas come up to the top half of the carb
3) warped carb top half which I have fixed as Lurker carls web site showed. it is not as good as carls but 100% better then when I started. It was warped up to almost 1/8" in a few spots.
4) I broke the idle tube off :shock: after pulling the two halfes apart not straight up and down man I was pissed.

I got the old idle tube out but only after breaking a easy out tip off in it.
I had to drumel around the hole to work at the easy out tip. fianly got it out and I used a #4-40 tap and found the old threads of the tube. I hope it was a #4-40. Then I took the old idle tube which broke off right at the base of the tube and re-thread it and screwed it in. It is now 3/16" short than it was. ( I have ordered a new one)

I got home and hooked it all up and it runs and the idle cicut adjustment screw now works!!!!!!!!!!!!!! the carb ran better than it ever has I could even start iff in third gear with out it dying or barley going.

One thing I need to figure out is now it is acting like the govenor is surging and it never did that before. sometimes it runs good and the next time you idle down it will surge you can kind of feel it very little at half throtal. Questio
is the govenor or carb not set right? Maybe a week spring on the gov?
or do you think it could be the idle tube being to short now that I borke it and fixed it till my new one comes?
any help?

oh yeah the good news is the TSC carb kit has the rubber tipped needle and seat and my carb no leaky any more!

Thu Jul 15, 2004 9:04 am

I have never (knowingly) dabbled with a Cub with a short idle tube, but I bet that 3/16" will never make a noticeable difference.

At idle, the throttle position should be held by the idle speed screw and the governor shouldn't come into play. Several things can affect the surging behavior, including fuel mixture, timing etc. But I expect you to have those things about on the mark. You need to check the linkage between the governor and the carburetor. First check the rockshaft extension (the rod) that comes out of the left side of the governor. It is keyed into the governor spring lever. If it is loose at the lever, snug it up as needed with shims, Lock-Tite or whatever it takes. There are some previous threads detailing this problem. Once you have that in shape, you adjust the linkage to the carburetor.

Engine off, unpin the clevis end of the linkage to the carburetor. Push the governor control fully forward. Hold the throttle plate wide open. Adjust the clevis to the longest position that will allow you to install the pin without moving any of the othe parts.

Most likely this will cure the surging. If it doesn't, you need to adjust the bumper spring on the front side of the governor. The adjuster looks like a stud with a jam nut. Loosen the nut then turn the adjuster in a bit at a time until the surging is gone. You want the engine off (fan!!) while you make the adjustments. You may want to unscrew the adjustment all the way to remove and clean the bumper spring before making the adjustment.

Thu Jul 15, 2004 9:13 am

when you say un-hook the clevis and push the govenor arm forwad do you mean towards the radiator?
Then you push the rob to the drivers seat to open up the throtal?
if that is correct then I unscrew the clevis to the line up point keeping the govenor arm pushed toward the radiator and the throat wide open pushing towards the drivers seat?
If that is what you mean then I think I went the wront way with the gov. arm last night when I put it back together. I didn't do that before but the tractor just ran bad.
thanks Jim

Thu Jul 15, 2004 9:25 am

What you need to do is:

1. unhook the governor/carb linkage at the clevis.

2. Push the governor control all the way forward ( also thought of as the throttle control, at the drivers seat).

3. Then reach around behind the carburator, and push the butterfly shaft to the rear of the tractor, so that it is set to full throttle. Then line up the holes of the linkage by adjusting the clevis, but not moving the linkage rod or governor arm. Let them rest where they are and only move the clevis yolk by turning it on the threads.

4. Reinstall clevis pin.

Hope this is clearer.

Thu Jul 15, 2004 9:34 am

when adjusting the govenor rod what postion should the throtal be set in the indicator on the sterring post?

Thu Jul 15, 2004 9:35 am

It should be set at full. Thats where you are confused. It is not really a throttle control, it is a governor control. Thats what I'm refering to in number 2 above. But most people call it the "Throttle".

Thu Jul 15, 2004 1:14 pm

I believe the threads on the idle tube are 4-48 (fine thread) instead of 4-40.

Thu Jul 15, 2004 1:27 pm

well crap if it was 4-48 it is now 4-40 and the new idle tube wont screw in.
such as life. I hope to get lucky and the short idle tube fix will work and I wont have to worry about it.

Thu Jul 15, 2004 1:29 pm

Chad, there are a lot of them out there running with no idle tube. I don't think you'll even notice.

Thu Jul 15, 2004 1:31 pm

thanks big dog! when I broke it I about had a heart attack! so proud I got the warp of the lid then break the idle tube.

Thu Jul 15, 2004 9:43 pm


I have had a similar problem to yours and had marked the proceedure in
my service manual. It reads as follows:

para 1 page 2-18

"(a) With engine stopped, advance the operator's engine speed control
lever to about half speed positon; sufficient to create tension on the
governor spring.

(b) Disconnect governor-to-carburator control rod (either end). Hold
carburetor throttle against its stop in wide-open position and adjust
length of governor-to-carburetor control rod so that it may be
reconnected freely without moving throttle lever or governor

(c) Lengthen control rod one turn from the above condition, to
compensate for wear, and reconnect."

Hope this helps out. I had three that I went exactly by-the-book and it
fixed all of them. Good Luck.

Fri Jul 16, 2004 6:00 am

Thanks guys for all the help! the carb is adjusted right and so is the gov.
I had to adjust it where the jam nut and screw is to finish taking the surging out of it. I have had the tractor 2 years and finaly got it running the way I wanted. it is nice taking off in third gear at half idle.
The carb was the main problem but thanks to LurkerCarl I got most of that taken care of.
Thanks again