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Throttle control - after rebuild cannot increase revs


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#1 humpy OFFLINE  

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Posted February 08, 2018 - 01:52 AM

Hi,

With the help of this forum, have  proudly rebuild 2 MTD tractors now :-) -- first one unfortunately has different carby setup to second one   so cant compare to help with following problem ..

 

  Everything on second tractor now works, choke system works and  engine starts and idles well,  i THINK the governor is working, but unsure   as I dont have easy access  to an area of thick grass to test...

 

BUT one remaining niggle...i cannot  increase the revs with the throttle lever..!

 

The tractor was pulled apart and sat in the corner for several months before I was able to re-assemble..

I am not sure if i have lost a small spring or connection from the throttle controls while it sat....

 

I have uploaded a video showing  engine running, and how moving the throttle engages the choke correctly, but does not change  revs, but if i stick a finger in and push back "carby lever" , i can make it rev fine  Http://cybersol.com.au/uploads/throttle3.mp4

 

Am also attaching a picture of back of linkage plate with possible  attachment points for a missing spring or wire?

AND  have also attached the best pic I could find from the B&S info, with exploded diagram of the throttle plate, and that does not seem to show any missing linkages?!!!

 

Am i totally barking up the wrong tree? Totally confused  at  how to attack this,

 

Cheers Will

Attached Thumbnails

  • briggs.jpg
  • IMG_20180208_155221776.jpg

Edited by humpy, February 08, 2018 - 01:54 AM.

  • boyscout862 said thank you

#2 secondtry OFFLINE  

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Posted February 08, 2018 - 02:15 AM

Would need more pictures to see what is going on. What you are apparently calling the "carby lever"  is in fact the governor arm. It should have a spring between it and the throttle linkage. When the throttle control is moved towards high rpm the spring should try to pull the governor arm in the same direction you are pulling it when you manually rev the engine. When you manually rev the engine with the governor arm you should feel the governor arm pushing back. This push back is the force that counter acts the spring tension trying to pull the throttle wide open. It is a balance between the governor push back and the spring tension that controls the rpm.   Hope this helps. Don


  • boyscout862 said thank you

#3 humpy OFFLINE  

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Posted February 08, 2018 - 03:12 AM

Hi,

Thanks for the input,  governor arm has a spring and  linkage attached, governor works and pushes back when i push finger against governor arm.

Have attached further pic, and uploaded vid showing gov arm moving with help of finger  and this moving  carby throttle to http://cybersol.com....oads/mower4.mp4

 

The main problem still exists... moving the throttle lever moves  the linkage slide at other end, but has no way or direct connect to throttle linkages on carby,  only connection/control  at moment is via governor system... which maintains revs,  but still means  so revs cannot be adjusted to full revs  etc , and as shown in the B&S diagram, nothing  I can see provides this action, so I dont know what part to ask any mower shops for etc

 

The only way it can work that i can see is a connection must be missing from the end of the throttle cable  linkage, that then goes to the governor arm,  so as to be able to set  the revs  to high or low, and then the governor will do its job maintaining the set revs...

 

BUT once again back to square one in that i cant see any B& S part in the diagram that would do that?!

Attached Thumbnails

  • IMG_20180208_175323387.jpg

Edited by humpy, February 08, 2018 - 03:24 AM.


#4 EricFromPa OFFLINE  

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Posted February 08, 2018 - 07:07 AM

Your Missing a spring.  

part #  Briggs and Stratton 796260 Spring-Governor

 

 

The S shaped part just pushes on the choke linkage.

 

Here this video will help for reference on where the spring hooks to.

 


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#5 humpy OFFLINE  

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Posted February 08, 2018 - 09:09 AM

Brilliant!  That is exactly what i need.. thanks so much :)



#6 secondtry OFFLINE  

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Posted February 08, 2018 - 09:56 AM

Your Missing a spring.  

part #  Briggs and Stratton 796260 Spring-Governor

 

 

The S shaped part just pushes on the choke linkage.

 

Here this video will help for reference on where the spring hooks to.

 

   A video can be worth 10000 words. Thanks.  Don


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