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Cannot Get My 10 Horse Briggs Running Right


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#1 quartermilecamel OFFLINE  

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Posted September 02, 2013 - 07:43 PM

engine model is 251417-0159-01.   Ususlly it will sputter but not start.  Has good spark.  Points magneto was replaced with the electronic version at some point.  Now we can get it to start but not rev very high.  Will not start with any amount of throttle at all.  I usually get it to start by cranking and sloowwwllyyyy increasing throttle a bit from low throttle but not much.  It has to be exactly in the sweet zone.  Compression is all over the place.  Ive seen 50, 60, 80, 105, 110.  Took out valves, lapped them and adjusted clearance once reinstalled.  Right at this point in time I think I can go out and start it but it wont rev very much.  Even at full actuall carburetor plate full throttle it just wont rev very much. Adjusting the screw which I think is high idle or high speed does absolutely nothing.  Using the choke just pisses it off and I wont get any fire at all.  Valves don't seem to be sticking.

This engine is on the bolens I bought for 20 bucks...in another thread.

also have noted backfiring out exhaust.  Some scoring on cylinder wall.... I have seen worse.  My guesses are sticking rings, bad carburetor(although the high speed screw did work before), loose valve seats. 

Used to be I could rev it, just was a witch to start or get continually running.  Now I cant rev it much.  Have taken apart carb many times now and blown it out.


Edited by quartermilecamel, September 02, 2013 - 07:59 PM.

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#2 chris m OFFLINE  

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Posted September 02, 2013 - 07:53 PM

It sounds like something is up inside the carb. Have you had this carb apart yet? Also have you checked to see if the governor is adjusted correctly?

These carbs can be finicky if not cleaned good, and every Briggs I seem to get a PO has usually messed with the governor and had them adjusted wrong.



#3 EricFromPa OFFLINE  

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Posted September 02, 2013 - 08:08 PM

Those old Briggs carbs are a pain in the butt.Once you get them clean and adjusted correctly though they are one of the easiest starting engines you can get.

 

Most of the old briggs I've had the Floats needed reset.They will not run worth a darn if the float is closing to soon.Won't have enough fuel in the bowl for the carb to work correctly.

 

I've had a few that would not run at all until I backed the main jet screw out another 2 1/2 turns.This happens because someone took the jet out ad didn't reinstall it correctly.The jet needs to be threaded the whole way up in or it blocks the fuel inlet to the main jet.


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#4 quartermilecamel OFFLINE  

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Posted September 02, 2013 - 08:16 PM

Ok yes it will run if you back out the bottom screw well probably an additional 2 and a half turns.  I did bend the nozzle jet a bit cause I didn't know you had to remove that to get the top of the float off but I bent it back and it seems to install ok...almost lol.  But even after I bent it back and reinstalled it I could rev it just fine....but that was before............when it actually did start!!!!  Have no idea how to set the float.


Edited by quartermilecamel, September 02, 2013 - 08:19 PM.


#5 quartermilecamel OFFLINE  

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Posted September 02, 2013 - 08:17 PM

It sounds like something is up inside the carb. Have you had this carb apart yet? Also have you checked to see if the governor is adjusted correctly?

These carbs can be finicky if not cleaned good, and every Briggs I seem to get a PO has usually messed with the governor and had them adjusted wrong.

Well I havnt messed with the governor other than removing the governor linkage shaft to the carb when I remove it.  I used compressed air to blow the carb out and every passage I could find.



#6 superaben OFFLINE  

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Posted September 02, 2013 - 08:21 PM

Large Flo Jet carburetors can be painful, just like Eric said. 

 

They are picky about adjustments.  They also hate air leaks.  Check around the gaskets. 

 

Ok yes it will run if you back out the bottom screw well probably an additional 2 and a half turns.  I did bend the nozzle jet a bit cause I didn't know you had to remove that to get the top of the float off but I bent it back and it seems to install ok...almost lol.  But even after I bent it back and reinstalled it I could rev it just fine...........when it actually did start!!!!  Have no idea how to set the float.

 

I would replace the nozzle.  If it is crooked it will not seal at the top of the passage, letting too much fuel in which might cause it to not rev up do to flooding.  They are not expensive in a good carburetor kit. 

 

To set the float, split the carburetor and turn it upside down, you are wanting to make sure the float is level with the upper body.  It should be sitting on top of the needle valve (shutting the inlet) and level with the upper body.

 

Ben W.


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#7 quartermilecamel OFFLINE  

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Posted September 02, 2013 - 08:36 PM

yes it does sound like its loading up..like its firing twice as slow as it should.  got a carb kit coming from ebay as I doubt any mower shop would have the kit.  It will have this nozzle in it. 

Anyone care to enlighten me as to symptoms of a loose valve seat, or sticking rings.  Compression all over the place is still stumping me.  Did drop a good amount of oil in it, probably more than I should of down the spark plug hole, and compression rose 15 to 20.



#8 WNYTractorTinkerer OFFLINE  

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Posted September 02, 2013 - 08:59 PM

engine model is 251417-0159-01.   Usually it will sputter but not start.  Has good spark.  Points magneto was replaced with the electronic version at some point.  Now we can get it to start but not rev very high.  Will not start with any amount of throttle at all.  I usually get it to start by cranking and sloowwwllyyyy increasing throttle a bit from low throttle but not much.  It has to be exactly in the sweet zone.  Compression is all over the place.  Ive seen 50, 60, 80, 105, 110.  Took out valves, lapped them and adjusted clearance once re installed.  Right at this point in time I think I can go out and start it but it wont rev very much.  Even at full actual carburetor plate full throttle it just wont rev very much. Adjusting the screw which I think is high idle or high speed does absolutely nothing.  Using the choke just pisses it off and I wont get any fire at all.  Valves don't seem to be sticking.

This engine is on the bolens I bought for 20 bucks...in another thread.

also have noted backfiring out exhaust.  Some scoring on cylinder wall.... I have seen worse.  My guesses are sticking rings, bad carburetor(although the high speed screw did work before), loose valve seats. 

Used to be I could rev it, just was a witch to start or get continually running.  Now I cant rev it much.  Have taken apart carb many times now and blown it out.

Me thinks you may need to pull things apart a tad more..  The different compression readings make me think it is something else..  The ACR spring could be gone/ busted and that will definitely cause the symptoms you are seeing..  Hold the phone!!  I looked up the engine and it doesn't have ACR..  Now I'm stumped as well..  Look in the Carb bore with the engine off..  The throttle plate should be wide open when you increase the throttle lever.  If it isn't, there is something wrong with either the governor settings or the governor itself.  A closed plate will definitely affect your comp readings as it restricts airflow into the cylinder.  Just an idea..


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#9 chris m OFFLINE  

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Posted September 02, 2013 - 08:59 PM

yes it does sound like its loading up..like its firing twice as slow as it should.  got a carb kit coming from ebay as I doubt any mower shop would have the kit.  It will have this nozzle in it. 

Anyone care to enlighten me as to symptoms of a loose valve seat, or sticking rings.  Compression all over the place is still stumping me.  Did drop a good amount of oil in it, probably more than I should of down the spark plug hole, and compression rose 15 to 20.

Those engines have a compression release mechanism. So you can't read compression on these with a gage, unless you where able to spin the engine in reverse. 

 

Disregard. I didn't realize this didn't have a comp release!


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#10 quartermilecamel OFFLINE  

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Posted September 03, 2013 - 03:37 AM

Those engines have a compression release mechanism. So you can't read compression on these with a gage, unless you where able to spin the engine in reverse. 

 

Disregard. I didn't realize this didn't have a comp release!

if they do not have a compression release, then when exactly should the intake valve be totally sealed to the valve seat(not able to turn it with your fingers) when the piston comes up on its compression stroke?  On the compression stroke, the intake valve fully seats with spring tension when the piston is between an inch and 2 inches(cant remember exactly)



#11 boyscout862 ONLINE  

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Posted September 03, 2013 - 04:21 AM

Check in the Manuals section for the B&S Repairmans Manual. It will give you specifics on the older engines. I got to suspect the ignition. Good Luck, Rick

#12 Bruce Dorsi OFFLINE  

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Posted September 03, 2013 - 09:40 AM

if they do not have a compression release, then when exactly should the intake valve be totally sealed to the valve seat(not able to turn it with your fingers) when the piston comes up on its compression stroke?  On the compression stroke, the intake valve fully seats with spring tension when the piston is between an inch and 2 inches(cant remember exactly)

 

On many of the B&S engines, compression release was designed into the lobe of the camshaft.  ....At slow (cranking) speed, a valve is lifted slightly off its seat, allowing a reduction in compression.  ....When the engine starts, this loss of compression is insignificant.

 

Your intake valve should have .005"-.007" clearance, and the exhaust should have .009"-.011" clearance.  (I always tried to set them at .006" and .010".) 

 

The foolproof way to check and set valve clearances is to check valve clearance when one valve is at maximum lift.  ....Check & set the intake valve clearance when the exhaust valve is fully raised.  ....Check & set the exhaust valve clearance when the intake valve is fully raised.  .....This method prevents false settings due to compression relief.

 

Also, be aware that on some B&S engines, the intake valve has a 30 degree valve & seat angle, while some engines have a 45 degree angle.  ....All exhaust valves & seats have a 45 degree angle.

 

It is very hard to detect a loose valve seat unless you see it out of position.  .....When the valves are out, a really loose valve seat will rotate in the block, but often they are snug until the engine heats up.  ......Loose seats in aluminum blocks are common, and easily repaired.  .....I have never witnessed a loose seat in a cast-iron block, though it could happen. 

 

Others have given advice on your carb rebuild and float setting.  .....When removing & installing brass carb jets, use a screwdriver wide enough to fill the slot in the jet.  ....Preferably, the screwdriver will have a flat (not tapered) end.   ....The idea is to use a tool that will not mar the area where the needle valve will seat.  .....Also, NEVER use force to tighten a needle valve against its seat.  ....Just use light finger-pressure to seat the needle, and then back-off the setting the required number of turns.


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#13 quartermilecamel OFFLINE  

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Posted September 03, 2013 - 02:07 PM

trying to think of a way to even spin it backwards.  Its electric start.  would amost have to get an electric motor, install a belt, with motor on backwards onto the low or high range pulley.  Or somehow install the starter on backwards. 

  We did check for a loose seat by using a small screwdriver to see if the seat moved when the valve was raised.



#14 quartermilecamel OFFLINE  

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Posted September 03, 2013 - 02:16 PM

The major cause of it not running correctly was the flywheel key.  Mr yours truly looked at flywheel key and it looked good, but didn't notice that it was only half of the key in the flywheel.  The crank was 90 degrees further advanced.  Guess I didn't tighten it good enough.  I thought I had read on the briggs site that the flywheel nut was 100 pounds.  Hoping this is correct , as Im using a torque wrench.


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#15 AVB OFFLINE  

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Posted September 03, 2013 - 04:30 PM

Don't put any lube on the crankshaft when replacing that key.






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