Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP

theticket

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
OHV Engine # 28N707 Type 0173-01. Was smoking terribly, almost to the point of not running, so I replaced the piston rings, properly I think. I inspected all moving parts, OK. I put on new gaskets also. Now, when I put it back together, I get spark, but no firing in cylinder. I have gas on spark plug when pulled to inspect and it sparks, it will not continue firing. Starting fluid is of no help either. I'm pretty sure I got all wiring back correctly. I don't really know how to check if a kill switch is doing its job or not. I have a switch mounted on the bottom of the seat, but it looks normal. The mowing deck is not installed at this time. I set the coil gap at .12. This is the first time I have ever replaced piston rings. Do I have a bad gasket? Do I need to adjust valves? What should I look at next to resolve my problem?
Many thanks
 
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bertsmobile1

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
Ok lets get this correct.
You told us you have spark
You told us the plug gets wet
You told us
it will not continue firing.
????
I am not quite sure what you mean by that statement? :confused2::confused2:

Does it fire, as in go bang at all ?
Does it go bang a couple of times & then stop ?
Do you mean you get a few sparks then no sparks ?
 

motoman

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
Try running cold compression test. Did you measure the bore for oval and taper? Rings have side clearance and need end gap . If new rings were put in a worn cylinder the compression could be low?
 

theticket

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
Ok lets get this correct.
You told us you have spark
You told us the plug gets wet
You told us ????
I am not quite sure what you mean by that statement? :confused2::confused2:

Does it fire, as in go bang at all ?
Does it go bang a couple of times & then stop ?
Do you mean you get a few sparks then no sparks ?

Sorry, I have spark when I ground the plug tip on the engine, so I assume it still sparks when it is screwed in, but it does nothing but turn over and over and does not start.
 

theticket

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
Try running cold compression test. Did you measure the bore for oval and taper? Rings have side clearance and need end gap . If new rings were put in a worn cylinder the compression could be low?


No, I did not measure anything. I am a novice. The lawnmower is 20 years old. I just ordered new rings and put them in.
 

Luffydog

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
Do a compression check and set the valves in..003/.005 & ex. .005/.007 see if that helps out. Might start at the valves first just to check if you don't have a compression tester. Or if you pulled the flywheel make sure the key way is still in.
 

ILENGINE

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
Also check the flywheel key. If not properly torqued when the flywheel was reinstalled could of sheared.
 

Boobala

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
OHV Engine # 28N707 Type 0173-01. Was smoking terribly, almost to the point of not running, so I replaced the piston rings, properly I think. I inspected all moving parts, OK. I put on new gaskets also. Now, when I put it back together, I get spark, but no firing in cylinder. I have gas on spark plug when pulled to inspect and it sparks, it will not continue firing. Starting fluid is of no help either. I'm pretty sure I got all wiring back correctly. I don't really know how to check if a kill switch is doing its job or not. I have a switch mounted on the bottom of the seat, but it looks normal. The mowing deck is not installed at this time. I set the coil gap at .12. This is the first time I have ever replaced piston rings. Do I have a bad gasket? Do I need to adjust valves? What should I look at next to resolve my problem?
Many thanks

THIS , should be your engine O/H Manual, I think you will find this, AND a camera (digital preferred) very useful, BEFORE attempting repairs, ( camera helps you "see" things as they WERE , makes re-assembly much easier ! )

https://drive.google.com/file/d/0B6NaqjIxWV1ybEN0LWo3azl6OUU/view
 

theticket

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
Do a compression check and set the valves in..003/.005 & ex. .005/.007 see if that helps out. Might start at the valves first just to check if you don't have a compression tester. Or if you pulled the flywheel make sure the key way is still in.


I got a compression tester and it read 125. I have not adjusted valves yet. I read on B&S website that they don't publish compression PSI, that they prefer a leak down test. Does this 125psi sound correct? The flywheel is turning and I wouldn't think that it would turn if the key snapped off or fell out, would it?
 

theticket

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  • / Briggs engine won't fire after new piston rings on Craftsman mower---15.5HP
THIS , should be your engine O/H Manual, I think you will find this, AND a camera (digital preferred) very useful, BEFORE attempting repairs, ( camera helps you "see" things as they WERE , makes re-assembly much easier ! )



Thanks for the information. Wish I had that before I started this adventure.
 
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