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

T

theticket

Member
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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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.
Click to expand...
????
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 ?
 
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?
 
bertsmobile1 said:
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 ?
Click to expand...

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.
 
motoman said:
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?
Click to expand...


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.
 
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.
 
Also check the flywheel key. If not properly torqued when the flywheel was reinstalled could of sheared.
 
theticket said:
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
Click to expand...

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
 
Luffydog said:
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.
Click to expand...


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?
 
Boobala said:
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.
Click to expand...
 
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