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Discussion Starter · #1 ·
My GC135 engine had the exhaust valve head break off. I torn engine down and the only damage appeared to be a few dings in the piston head so I replaced the exhaust valve and reassembled the engine. Now it won't start. It tries to but seems as though it doesn't have enough compression to actually keep runing. I removed the plug and attached a air line in the plug hole and I feel and hear air coming out from the exhaust port when the valve is closed. Just wondering if anyone out there has ever had this experience or knows how much of a compression leak you could get by with and still have the engine run.
 

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Did you lap the valve when you installed it? You may have damage to the seat from when the valve broke off. I would wait for someone who better knows Honda engine to chime in, but you may have to Cut and relap the valve seat.
 

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Discussion Starter · #3 ·
I didn't lap the valve seat. I did a visual inspection and didn't see any damage to the seat area. I don't have any tools to do it anyway and a machine shop would probably be more expensive than a new head....
 

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Did you set your valve lash? Maybe your valve is just not closing all the way.
 

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Discussion Starter · #8 ·
Nope, check that also. It's fine. But I noticed today that when the piston is at TDC and both valves are in there closed position, there is some air leaking past the intake valve also. So maybe when the exhaust valve broke, it damaged the intake valve also.
 
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