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The Tuul Crib

16 horse runs only when the choke is closed

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The Tuul Crib

Got this fresh 16 horse running today

end it only runs with the choke closed but runs perfectly could this be a float issue?

it quits when you open the choke.

Edited by The Tuul Crib

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squonk

How many turns do you have the main jet adjustment backed out?

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Ed Kennell

Excess air leaking in around the throttle plate shaft or a bad seal with the block can cause this problem.

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stevasaurus

You are sucking air, closing your choke shuts the air down.  Carb adjustment, bad gasket, leaking clamp...also, something cutting off fuel flow can do this...a spider in the petcock for instance.  Spraying carb cleaner around and listening for engine changes can pin point the leak.  Cranking the engine with the feed hose off at the fuel pump...and after the fuel pump.  Things like that.  :occasion-xmas:

 

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The Tuul Crib

I'm a little worried. This engine has been bored out to 30 over. It is sucking a lot of air !  It s only a few thousands from being a 4 inch bore! I haven't checked the compression yet as I just got it running.

can't wait to see what it is on this one!

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ZXT

It's lean for sure. Is this a known good carb? If you don't know the history on it I'd pull it apart and clean it. If you have a good 14/16HP carb on another machine you could throw on this engine it would be a good diagnostic tool!

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sqrlgtr

Its been my experience in this type situation that the carb was gummed up/stopped up and required a tare down and thorough cleaning.If nothing is broke the hardest part is taking carb off of motor :D.Most of the time if throttle shaft is wore you can still get them to run but are hard to get them to idle right because of the extra air getting by throttle shaft:wacko:.BTW thats unfiltered air and would not be a good idea to operate engine in real dusty conditions.Alot of the fuel today is junk and will gum one up in a little while,especially if the machine sets a few days between running.I try to run 100% gas but sometimes its hard to do and sometimes I really dont know if it really is 100% (no corn) fuel:twocents-02cents:

 

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pullstart

Carb clean might be a good helper tool when it’s running, spray around the carb base, throttle shaft, etc.  if it revs up or bogs hard, you’re getting more air through the system where it shouldn’t be.  Like Steve mentioned too, it could be a fuel supply issue.  Try bottle feeding the carb direct to see if the issue goes away.

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The Tuul Crib

The thing is l rebuilt the carb allready

l just got done yesterday putting on a new

gasket to see if that helped. No diff!

Must be the throttle shaft suckin 

alot of air.

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echris

If you just rebuilt the carb and are sure it's clean etc, @stevasaurus idea is probably the easiest next step. By spraying carb cleaner etc around all the joints between the carb and the engine, you will definitely hear the idle change if you have an air leak because it will suck in the liquid and choke it out.

I doubt it would be float unless it's way, way off. It should still idle without choke even if the float bowl is a bit low.

Also, when you rebuilt the carb, did you replace everything or just do a cleanout? I've seen air leaks around worn adjuster screws. Sometimes the springs on the screws are so worn the screw moves and you may not realize it.

Just throwing some ideas out there. Hope you get it sorted!

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The Tuul Crib

I haven't had a chance to get back to it since I got it started. I'm suspecting the throttle shaft will need to be done.Did a chem dip on the carb and then put an

oem carb kit. Any ideas were to get 

A kit to fix the throttle shaft?

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953 nut
12 hours ago, The Tuul Crib said:

Any ideas were to get 

A kit to fix the throttle shaft?

If you have a hardware store the handles the Hillman line of hardware ask for thrust bushing # 58087, you will need two of them. McMaster-Carr also has them, 5906K56, they come in a package of 10 for about the same price as two at the hardware store. They are 1//4" ID, 7/16" OD and about 1/16" thick.

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The Tuul Crib
3 hours ago, 953 nut said:

If you have a hardware store the handles the Hillman line of hardware ask for thrust bushing # 58087, you will need two of them. McMaster-Carr also has them, 5906K56, they come in a package of 10 for about the same price as two at the hardware store. They are 1//4" ID, 7/16" OD and about 1/16" thick.

Is it best also to replace the throttle shaft?

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oldredrider

With new bushings, you shouldn't have to change the shaft.

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953 nut
7 hours ago, The Tuul Crib said:

Is it best also to replace the throttle shaft?

:text-yeahthat:         The shaft is hardened steel, the body it passes through is aluminum, chances are the shaft is fine.

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pfrederi
1 minute ago, 953 nut said:

:text-yeahthat:         The shaft is hardened steel, the body it passes through is aluminum, chances are the shaft is fine.

 

Richard:  That was my first thought also.  I am working on a Kohler carb on my M-16.  The throttle shaft was nonmagnetic and brass colored.  Of course one of teh butterfly screw sheared off.  The screws were bras i had to drill out the remains and run a 3-48 tap through to clean it up.  Looked and felt like brass.... I could feel a bit of wear on the shaft but after putting it back in with 2 new seals it was pretty tight but this engine didn't have a lot of hours on it.  so maybe with more time a new shaft might have been in order... Do not know...  If it had a steel shaft i am sure it would not need replacement.

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953 nut
19 minutes ago, pfrederi said:

after putting it back in with 2 new seals it was pretty tight

The part of the shaft where the thrust washers go has only seen wear from the felt bushing that was installed in the factory.

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pfrederi
43 minutes ago, 953 nut said:

The part of the shaft where the thrust washers go has only seen wear from the felt bushing that was installed in the factory.

Well the felt was long gone:P but that explains why it was tighter.

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81blackhood

9E5AF234-F8F2-48B3-A79F-1391CB1E0278.jpeg.9c6984d61ab862a6ee9a65af4e3fd33d.jpeg
If you have a dial indicator you can measure shaft play.  I think the maximum is .010

EF4AD1E4-8FE3-4F7F-87B0-A685623EB2B4.jpeg.4755e8bfd18ab51e99b763034e7e9626.jpeg

with bushings installed

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