Surging only at full throttle

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Re: Surging only at full throttle

Postby Bob McCarty » Thu Aug 08, 2013 8:54 pm

If you have a set of nut drivers, those also work well for the discharge tube and main jet. The idle tube is threaded in about 1/4". If you're sure you need to remove it, spray it for several days with a penetrating oil and then slowly wiggle it back and forth with a good pair of needle nose pliers until it will let you unscrew it. You risk breaking it even if you are careful, and that repair involves drilling and chasing the threads. A rebuild kit probably isn't needed, a new "OEM" body gasket may do it. Check to make sure the top isn't warped by placing the halves together without the gasket and see if it fits evenly all around.

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Re: Surging only at full throttle

Postby Rick Spivey » Fri Aug 09, 2013 5:09 am

The two holes Raymond mentioned, in the carburetor throat at the throttle plate, are often plugged; a piece of copper wire will open them right up and make a marked change in idle characteristics on some cubs. Also make sure all loose debris is flushed out, or you will immediately stop up the main jet; it also can be cleaned with a strand of copper wire.
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Re: Surging only at full throttle

Postby Eoghan » Fri Aug 09, 2013 3:05 pm

Problem solved! thanks to Everyone for the suggestions. It turned out to be both the carb AND the governor. This morning I cracked open the carb again and sure enough, those tiny holes in the idle circuit were plugged up! Had to jigger some copper wire around in there and eventually they cleared out. That solved the low idle problem (she purrs now with the throttle on the lowest setting!), but it was still surging at high rpm so i figured i'd mess with the governor. I couldn't quite tell if the linkage was touching at all, so I bent it until i was darn sure that it wasn't. that didn't stop the surging, but the throttle was a lot smoother, so i guess that was part of the problem after all. Finally, i turned in the bumper spring little by little and eventually it stopped the surging. I'm not sure how many turns it took, but It doesn't seem to have problems under load so i guess it wasn't too much. I Went out mowing and it handled the thick stuff way better than it used to! The only time it died on me was when i took it through some THICK grass that I haven't cut all year and is full of bindweed. I can live with that!

:thanx: :worthy: :{_}: :||):
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Re: Surging only at full throttle

Postby RaymondDurban » Fri Aug 09, 2013 3:11 pm

Glad to hear everything has worked out!
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Re: Surging only at full throttle

Postby Eoghan » Fri Aug 09, 2013 5:21 pm

I'm sure this is just the beginning of my adventures with this tractor. I'll continue to haunt this forum and learn as much as I can. these cubs sure are fun to play with (not to mention functional)!
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Re: Surging only at full throttle

Postby Rudi » Fri Aug 09, 2013 8:39 pm

Eoghan:

Coming in to this a bit late... the guys had you well covered so no need to duplicate or confuse. Let me just say G'day to you and proceed with what I normally do :

Image to Farmallcub.com :big smile: Forum Family. And you have come to the right place for all things Cub related. If you click on the Site Rules, Regulations, & Important Information, it will point you to :arrow: the Welcome Wagon wherein you will find links to many useful sites and topics. One of the most important resources are Owner's Manuals, Parts Catalogs and Service Manuals. The Cub Manual Server is the home of the jpg versions and the PDF Manuals -- well the pdf's of course :wink: Enjoy!.


Recommend that you might wish to take a little time and read the info at the links above. There really are a lot of resources available to our members and it continuously grows.

One of the other things is the Cub Book of Knowledge aka CBoK. It gets updated usually regularly .. mostly when there is snow on the ground and I is not so busy trying to play with my own Cubs etc.. but one of the things you might want to think about is taking care of the Fuel Circuit. DIrt and crud a happy carb does not make .. as you have just found out. There are a few things you can do on top of making sure the stock system is clean and working properly. This thread encompasses the previous 2 upgrades and adds a bit - How To Upgrade A Cub Fuel System. It isn't a have to do but a nice to do upgrade if you like it. Makes for less maintenance down the road if everything from Point A to B is clean and shipshape.
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Re: Surging only at full throttle

Postby Boss Hog » Fri Aug 09, 2013 9:08 pm

Eoghan wrote:I'm sure this is just the beginning of my adventures with this tractor. I'll continue to haunt this forum and learn as much as I can. these cubs sure are fun to play with (not to mention functional)!

If you find out that the governor is not responding as is should with the screw turned in, you can replace the spring on the outside and turn the screw back out some :wink: the spring is only 10 bucks or so
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