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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Engine Intermittent Cutting Out of One Cylinder
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<blockquote data-quote="oexing" data-source="post: 97748" data-attributes="member: 1493"><p>Seems to me quite obvious, at least one of three components in that cylinder does not seal well. Get a spark plug thread adapter and pressurize that cylinder with air with both valves closed. Then listen to hissing in the carb mouth, no hissing: Inlet valve OK. Listen at the silencer end: hissing means exhaust valve not tight. Or if both valves OK, listen for hissing from the engine case, at one valve inspection cap or so: Hissing means piston rings not sealing well. </p><p> Now you can dig deeper: If one or both valves cause hissing, off with the head and test valve sealing with bearing blue on the faces. That may show a valve that has a runout or else the seat ring is overdue for machining the seat face , depending on the blue marks. If both valves allright, then there is a severe problem with piston rings or cylinder bore, seizure and scoring. Anyway , a decent maintaining of pressure is first action, all else is secondary. </p><p></p><p> Vic</p><p>[ATTACH=full]22886[/ATTACH]</p></blockquote><p></p>
[QUOTE="oexing, post: 97748, member: 1493"] Seems to me quite obvious, at least one of three components in that cylinder does not seal well. Get a spark plug thread adapter and pressurize that cylinder with air with both valves closed. Then listen to hissing in the carb mouth, no hissing: Inlet valve OK. Listen at the silencer end: hissing means exhaust valve not tight. Or if both valves OK, listen for hissing from the engine case, at one valve inspection cap or so: Hissing means piston rings not sealing well. Now you can dig deeper: If one or both valves cause hissing, off with the head and test valve sealing with bearing blue on the faces. That may show a valve that has a runout or else the seat ring is overdue for machining the seat face , depending on the blue marks. If both valves allright, then there is a severe problem with piston rings or cylinder bore, seizure and scoring. Anyway , a decent maintaining of pressure is first action, all else is secondary. Vic [ATTACH=full]22886[/ATTACH] [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Engine Intermittent Cutting Out of One Cylinder
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