Leaky carb. B&S 8hp lawn tractor ???

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  #1  
Old 05-30-08, 05:22 PM
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Leaky carb. B&S 8hp lawn tractor ???

The carb. on my Ford R8 with a B&S 191702 2139-01 83113010 is leaking through the over flow drain on the bottom of the carb. (little round thing with some sort of screen on it).

Only thing is it only happens when it's running ? When it's off it will never drip.

I tried bending the tab on the float slightly, still getting the same drip when it's running !?

Should I still be looking at the needle and seat, or could something else cause this ?


Thanks
Wayne.
 
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  #2  
Old 05-30-08, 09:39 PM
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Sounds like you might have a slightly burned valve, or the valve clearances are too tight. That's common even on old flatheads like yours when they've been run a lot over the years. It causes a little bit of gas spitback through the carb...can be enough to cause drips. It usually is accompanied by hard starting/excessive cranking before it starts.
 
  #3  
Old 05-31-08, 05:19 AM
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Originally Posted by cheese View Post
Sounds like you might have a slightly burned valve, or the valve clearances are too tight. That's common even on old flatheads like yours when they've been run a lot over the years. It causes a little bit of gas spitback through the carb...can be enough to cause drips. It usually is accompanied by hard starting/excessive cranking before it starts.

That's exactly whats happening !

It all started when I recently did the crankcase gasket. The tractor was always very easy to start, still is.. only I was kinda thinking... Hmmm seems a little harder to pull ? naa.. maybe I'm just getting weaker but sure enough what you describe is happening. The tractor starts on a half pull every time!

When I did the crankcase gasket I also did the carb. and it has been operating great.. no surging, only the drip.

I didn't do the head until the other day, thinking maybe carbon d up causing hard cranking. So I pulled the head.. surprisingly clean in there, valves looked really good.

So it would seem I messed up the clearances somehow.

How would one go about correcting this.

The gasket I removed was paper thin as was the one I installed.

Did I tighten the bolts too tight !?

Thanks for the help Cheese.
 
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Old 05-31-08, 08:37 PM
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Ok, I meant hard starting as in crank, crank, crank, no joy, spray ether, etc... then finally...vroom...

I didn't mean hard to turn...if anything, it usually makes it easier to turn over. If yours is harder to turn over than usual, and starts on a half pull, it could be that the flywheel key is "pushed" (partially sheared). This would throw the timing off a little, causing it to tend to kick back a little, and fire a tad prematurely (just before the intake valve gets fully closed) which would cause some spitback through the carb, producing your symptoms.
 
  #5  
Old 06-01-08, 03:55 AM
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I'm gonna have a go at that flywheel today and check the key...

Thanks again Cheese

Wayne.
 
  #6  
Old 06-01-08, 05:42 PM
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Thumbs up

Originally Posted by cheese View Post
Ok, I meant hard starting as in crank, crank, crank, no joy, spray ether, etc... then finally...vroom...

I didn't mean hard to turn...if anything, it usually makes it easier to turn over. If yours is harder to turn over than usual, and starts on a half pull, it could be that the flywheel key is "pushed" (partially sheared). This would throw the timing off a little, causing it to tend to kick back a little, and fire a tad prematurely (just before the intake valve gets fully closed) which would cause some spitback through the carb, producing your symptoms.

Ok I started pulling the flywheel today (was working on other tractor/reassembled transmission today) and first thing I notice is the flywheel bolt was fairly loose.

And sure enough your right again Cheese. Looking down at it, cause I haven't actually pulled the flywheel yet, you can see that the key is just slightly (as you put it) pushed. If you look at the edges of the shaft and the edges of the flywheel you can see them slightly out of alignment.

So now that I have found the correct bolts to fit the flywheel for my puller I will have a go at it tomm.


Thanks again Cheese
 
  #7  
Old 06-01-08, 10:18 PM
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Sounds like you've got it pinned down! Let us know how it goes!
 
  #8  
Old 06-02-08, 06:50 PM
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Pulled the flywheel today and all went well. Running good now, easier to pull and no drip from the carb. and much, much better on gas !

I noticed the little briggs&stratton flywheel key is not a very snug fit and add in the loose flywheel nut and I guess when I was over by the dog runs cutting last week I bottomed out a couple of times and thats probably when the flywheel moved out of whack !?

I tightened the flywheel bolt once then removed it to see if it moved which it hadn't so I added a little lock-tight and away we go..


Thanks again Cheese

Cheers
Wayne.
 
  #9  
Old 06-02-08, 08:38 PM
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Glad you got it fixed and thanks for the update!
 
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