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The engine won't "pop" with starter fluid squirted into the head space. I measured the compression and it was below 50psi. Looks like a valve problem. Does anyone have any idea what the compression should be? How difficult is it to replace a valve?
 

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100 or better, 90 being ok, other things besides a valve would be... a head gasket leak, its not getting spark to even ignite the fuel, or the plug is fouled, maybe a sheared flywheel key,( it'll give spark but will be off timing ). that or maybe the valve, but a bad sealing valve. did it just start doing this?
 

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It had been getting progressively harder and harder to start. During the last operation it shut down upon running out of fuel. I didn't run it for 2 weeks then I found the problem when I tried to start it. I replaced the plug with a new plug, cleaned the fuel tank and cleaned the carb. The pressure washer pump connected to the engine rotates when I turn the engine over in attempts to start it. The plug does spark when held against the case as I rotate the engine. Compression is actually closer to 25psi.
 

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The engine won't "pop" with starter fluid squirted into the head space. I measured the compression and it was below 50psi. Looks like a valve problem. Does anyone have any idea what the compression should be? How difficult is it to replace a valve?
I just had a NO compression with GCV190. Tried brake cleaner in carby and cylinder , thru plug hole.. Replaced the plug and after a series of cord pulls,still no luck. I then emptied oil and took valve cover off and found inlet valve STUCK fully open. Lucky spring tension is minimal , so manually compressed spring and removed. Pliers on top of valve stem and pulling freed valve. Sprayed some lube on it and it then moved easily.Very briefly ( 1 sec ) engine run, without oil,cause need a new valve cover....which are hard to find.
 

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I just had a NO compression with GCV190. Tried brake cleaner in carby and cylinder , thru plug hole.. Replaced the plug and after a series of cord pulls,still no luck. I then emptied oil and took valve cover off and found inlet valve STUCK fully open. Lucky spring tension is minimal , so manually compressed spring and removed. Pliers on top of valve stem and pulling freed valve. Sprayed some lube on it and it then moved easily.Very briefly ( 1 sec ) engine run, without oil,cause need a new valve cover....which are hard to find.
Don’t forget there is decompression valve and your reading will not indicate correct on just turning motor.
 
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