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FJR Motorcycle Forums
Technical & Mechanical Problems
Valve Theory 101
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<blockquote data-quote="bergmen" data-source="post: 1307400" data-attributes="member: 15189"><p>This issue was far more common back in the day when we had cast iron valve seats (mid 60s cars/trucks) and dirty gasoline and oil that would generate carbon deposits. Regardless of the adjustment (most were hydraulics but many were manual), a bit of carbon would get between the valve a seat creating a leak that would "flame cut" the valve and seat, almost always the exhaust. Very common back then.</p><p></p><p>Fast forward to today and most modern engines have extremely hard valves and seats so leaky valves are very rare, unless the clearances are too tight as others have mentioned. Also, if the valve is being propped open when it is supposed to be closed, it is very likely that the cam lobe will get damaged since there is no room for a film of oil to generate.</p><p></p><p>Dan</p></blockquote><p></p>
[QUOTE="bergmen, post: 1307400, member: 15189"] This issue was far more common back in the day when we had cast iron valve seats (mid 60s cars/trucks) and dirty gasoline and oil that would generate carbon deposits. Regardless of the adjustment (most were hydraulics but many were manual), a bit of carbon would get between the valve a seat creating a leak that would "flame cut" the valve and seat, almost always the exhaust. Very common back then. Fast forward to today and most modern engines have extremely hard valves and seats so leaky valves are very rare, unless the clearances are too tight as others have mentioned. Also, if the valve is being propped open when it is supposed to be closed, it is very likely that the cam lobe will get damaged since there is no room for a film of oil to generate. Dan [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
Valve Theory 101
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