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BS 18.5HP Intek: Engine racing


Heffe's Avatar
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Join Date: Apr 2007
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04-08-07, 02:00 PM   #1  
BS 18.5HP Intek: Engine racing

Greetings all: my Craftsman lawn tractor would not start so I had a Sears tech come by (2 days ago). He adjusted the valves and it fired right up. I used it for about 15 minutes that evening.

Began using it again yesterday and after about 15 minutes I noticed that the engine seemed to be running a little faster than normal...then after a minute or so it would back down some...seemed to be related to load. I turned a corner and then the engine started racing like crazy. The throttle had no affect unless I put it into choke. I mean it was going really really fast. I shut it down because it was a little scary. I checked the throttle cable and it seems to be fine, and like I mentioned, it goes into choke no problem.

I thought it might be something stuck because of the cold temps outside but it was waaaayyyy faster than it has ever run on full throttle. I'm guessing it is the governor, but its hard to look at the external parts of it as it is behind a plate.

Below are the engine specs, thank you in advance for any words on this problem!
Heffe

Briggs 18.5 HP Intek OHV single valve model number 31P777 Type 0348-E1

 
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puey61's Avatar
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04-08-07, 02:42 PM   #2  
It sounds as though you have a governor related issue, if the throttle shaft (in the carburetor) is not "frozen". To adjust the static adjustment on the governor do as follows: Loosen the governor shaft arm nut slightly; Manually move the throttle linkage to wide open throttle (WOT) position (on the carb) and hold there; Using a common pliers, grab ahold of the governor shaft and rotate it in the same direction as is needed to obtain WOT. In other words, if you had to move the linkage leftward for WOT then you will rotate the governor shaft counterclockwise or clockwise if you moved the linkage rightward; With the linkage and shaft held in proper positions, retighten the governor arm nut back down. Done! This is the only external governor adjustment possible. If after you have the static adjustment set absolutely correct and you know the throttle shaft is not "frozen" and you still have an overspeeding issue then you will have an internal governor issue and would then need to remove the engine and get inside crankcase.

 
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04-08-07, 02:55 PM   #3  
RE: BS 18.5HP Intek: Engine racing

Posted By: puey61 It sounds as though you have a governor related issue, if the throttle shaft (in the carburetor) is not "frozen". To adjust the static adjustment on the governor do as follows: Loosen the governor shaft arm nut slightly; Manually move the throttle linkage to wide open throttle (WOT) position (on the carb) and hold there; Using a common pliers, grab ahold of the governor shaft and rotate it in the same direction as is needed to obtain WOT. In other words, if you had to move the linkage leftward for WOT then you will rotate the governor shaft counterclockwise or clockwise if you moved the linkage rightward; With the linkage and shaft held in proper positions, retighten the governor arm nut back down. Done! This is the only external governor adjustment possible. If after you have the static adjustment set absolutely correct and you know the throttle shaft is not "frozen" and you still have an overspeeding issue then you will have an internal governor issue and would then need to remove the engine and get inside crankcase.
Thank you for the quick reply. I have a couple of questions as it relates to setting the static WOT position on the governor:

1. Do I move the throttle to WOT via the cable/throttle lever or move it on the carb with my hand?

2. I understand the clockwise and counter clockwise motion your talking about on the governor shaft, however I'm not sure regarding the direction of the throttle linkage. As I look at it I'm perceiving forward and backward on the throttle/carb - toward the front of the mower or toward the back. I'm an imbecile haha.

Basically as I look at the carb and the governor shaft (going into the engine) is below it by about 5". The arm on that also, in my perception is front to back in motion, except that it doesn't appear to move more than about an 1/8th of an inch in either direction when I used the throttle lever.

Thank you again Puey61 for your input!
Heffe

 
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04-08-07, 03:05 PM   #4  
Using this as a reference http://www.thepowerportal.com/scripts/EmpartISAPI.dll?MF&app=BASE&session=b1225cca-0d83-4884-9c5c-784e8690a04c&cat=1&TF=epcFrame&assem=96211&highlightNode=No&selAssem=126347&mdDescrip=31P777-0348 (copy and paste into your browser), reference 202 is the throttle link and this is the first move you make (after the nut (reference 505, in the web link I provided) has been loosened, that is). You will pinch it between your thumb and forefinger and move it in the direction to obtain full throttle on the carburetor. I believe this will be a leftward direction (as looking at it from the carburetor side of the engine) and therefore the governor shaft (reference 616, in the web link) rotation will be CCW.

 
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04-08-07, 03:10 PM   #5  
Thank you Puey, as I paste the entire link into my browser the reply from the server is "undefined" on the webpage and that is all. I'm sorry for the trouble. Can I go to the initial site and type something specific into a search to get to the same place that you referenced?

Thank you ,
Heffe

 
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04-08-07, 03:49 PM   #6  
Sorry, this is a dealer only site and I wasn't sure if it would work. You shouldn't, anyhow, NEED this link. Just read my posts closely and perform as indicated.

 
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