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

theticket · Feb 18, 2018

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

bertsmobile1 · Feb 18, 2018

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 · Feb 19, 2018

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 · Feb 19, 2018

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 ?

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 · Feb 19, 2018

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?

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 · Feb 19, 2018

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 · Feb 20, 2018

Also check the flywheel key. If not properly torqued when the flywheel was reinstalled could of sheared.

Boobala · Feb 20, 2018

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

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 · Feb 20, 2018

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.

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 · Feb 20, 2018

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.

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

More options

theticket

Member

bertsmobile1

Lawn Royalty

motoman

Lawn Addict

theticket

Member

theticket

Member

Luffydog

Well-Known Member

ILENGINE

Lawn Pro

Boobala

Lawn Pro

theticket

Member

theticket

Member

Footer Links 1

Footer Links 2