FC420V Exhaust back fire

[Richie F]

Engine is a 14 hp. on a Scag walk behind mower.
End of season started with no problem and moved into shed.
This season won't start but only pop out the exhaust when trying to do so.
That shows the engine has fuel,spark and compression.
Have checked valves and are in spec.
Pulls over with no problem. Compression release is working correctly.
I thought timing might be off and inspected the key on flywheel and it's fine.
Is there an issue with the coil on this engine ?
Thanks.

 

[DunDikke]

Probably not getting enough or bad fuel. Iff you spray some carb cleaner or brake cleaner in the intake does it start then?

 

[Richie F]

No
Has fresh gas.

 

[StarTech]

Probably has a bad ignitor module. I had even one to shoot an one foot flame out of the exhaust and sound like a .357 magmum going off. Definitely got my attention that day.

 

[Richie F]

This engine doesn't have that, it's FC420V, integral coil.
Did compression check and found zero (0) compression.
Brought piston up to TDC, backed off the valves and blew regulated air into the cylinder, 30 psi.
Air came out the exhaust.
Removed the head, found no bent push rods or valve damage.
Turned the head over so combustion chamber was level face up and filled with mineral spirits.
Leakage out exhaust port.
Did notice that it looks like the exhaust valve guide has moved down towards the backside of the valve head.
Can't find any information on if this if it can be a Kawasaki design problem.
Can't find specs to measure the height of the guild either.

 

[Scrubcadet10]

In most Kawasaki engines I've worked on, the valve guides are generally the same height,(I wouldn't take that to the bank, I haven't seen every Kaw.) I've seen a few Kawi's with the exhaust valve guide pushed up into the head, might try lapping the valve, which grinds the valve seat and valve together to create a fresh sealing surface,

 

[StarTech]

Curious to which spec the FC420V you have as the FC420V-AS10 has ignitor?

 

[Richie F]

OK update
Measured the height of the intake guide and made a spacer that height.
Installed spacer (stack of washers) over the exhaust guide and jacked it back up using a 1/4" bolt and nut.
Using a punch I staked the head close to the guide on the top and bottom of the guide itself.
Use a wire wheel and cleaned the valves and one for the valve seats also.
Assembled the head, leveled the chamber and put mineral spirits in the chamber. No leaks.
Assembled the engine and problem fixed. Engine runs.
How long before the guide moves again don't know.

 

[Scrubcadet10]

Staking them usually holds them tight! I know it works good On valve seats.

 

[Richie F]

Been repairing cars, trucks, snowmobiles and lawn equipment for many years.
Was taught that trick when I first started out in the automotive field.
Thanks for your reply.