I've been working my way through a host of fuel and electrical problems with a JD LX178 that I bought on an auction. Finally got it running nicely, let it run for about 10 minutes before shutting it off. Went to start it a few days later and couldn't get it to fire at all - not even a pop. After the usual fuel and spark checks I find that it has almost zero compression on both cylinders. Any guesses as to cause? Seems odd that both cylinders could lose compression at the same time.
Kawasaki FD501V - Lost compression
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bertsmobile1
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check to se if the valves are moving when the engine rotates.
If not suspect a failed cam
Some of these engines had a plastic cam gear that was not quite up to the job.
If not suspect a failed cam
Some of these engines had a plastic cam gear that was not quite up to the job.
Thanks. Was guessing it might be cam related. Just seems odd that it was shut off running and never had any fire after that. Cam gear failed while cranking? Does the cam run off the spur gear that's on the bottom of the crank? Any way the key can work loose?
bertsmobile1
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Yep
Runs off the gear on the end of the crank.
Runs off the gear on the end of the crank.
Hammermechanicman
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Be sure to get a new all steel cam. Don't try to save money. Not if the plastic cam will fail but when it will fail.
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I noticed in the IPL it showed two Cams.
When I pulled the rocker covers I found one intake pushrod not in contact with the rocker and the other one bent. I loosened the valves up with penetrating oil and got it running again but guessing that I should have pulled the heads and cleaned carbon off the stems. Will have to see if it continues to run or if the valves stick again.
cpurvis
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Valve guides are susceptible to movement when the cylinder head gets too hot. Valve guides are steel and the cylinder head is aluminum and are assembled with a press fit. The hotter the head gets, the less gripping force there is between the two to hold the guide in place, as aluminum expands more than steel with an increase in temperature.
The best thing you can do to prevent this is take the shroud off periodically and blow out any dirt and clippings that have accumulated on the cylinders.