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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Comet Breathers
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<blockquote data-quote="pa.jello" data-source="post: 45178" data-attributes="member: 2992"><p><strong>Comet Breather</strong></p><p></p><p>Hi - Like you I was a learner in 1982 and had to learn all the wrinkles about Comets. There is nothing wrong with the design and as already has been mentioned, the timing of the Breather Pinon on the shaft is essential. I opened out the slot on the pinion ( to allow a greater flow of pressure) and ensured the timing of the downward piston stroke was as per the degree timing when the slot/valve opened allowing the maximum gas to flow and to release the crankcase pressure. The use of a banjo with a plastic flexible tube to temporarily replace the evacuation pipe (A71/1AS) allows you to blow down the tube while rotating the crankshaft and checking the fitted timing degree disc to see that the air shuts off/on at the correct degree timing. If you get these correct, in my opinion there is no need for the Elephant trunk. The restrictor disc is also essential behind the rubber seal to prevent too much oil traveling to the overhead gear. With the valve lifter, I added an extra thick rubber washer behind E217 and added a spring to ensure the rubber remained seated on the case stopping oil from evacuating the case. This stopped the oil messing the gearbox and dripping onto the exhaust pipe.</p><p></p><p>Another trick is to use a light running in oil on a new engine and new rings as it allows the rings to bed in. If you use 50 grade oil, the oil will be pumped out into the exhaust and the rings will certainly not bed in at all.</p><p></p><p>My Comet has completed many thousands of miles since 1982 and does not use oil as you have experienced following the mods that I made.</p><p></p><p>I wish you well from NZ</p></blockquote><p></p>
[QUOTE="pa.jello, post: 45178, member: 2992"] [b]Comet Breather[/b] Hi - Like you I was a learner in 1982 and had to learn all the wrinkles about Comets. There is nothing wrong with the design and as already has been mentioned, the timing of the Breather Pinon on the shaft is essential. I opened out the slot on the pinion ( to allow a greater flow of pressure) and ensured the timing of the downward piston stroke was as per the degree timing when the slot/valve opened allowing the maximum gas to flow and to release the crankcase pressure. The use of a banjo with a plastic flexible tube to temporarily replace the evacuation pipe (A71/1AS) allows you to blow down the tube while rotating the crankshaft and checking the fitted timing degree disc to see that the air shuts off/on at the correct degree timing. If you get these correct, in my opinion there is no need for the Elephant trunk. The restrictor disc is also essential behind the rubber seal to prevent too much oil traveling to the overhead gear. With the valve lifter, I added an extra thick rubber washer behind E217 and added a spring to ensure the rubber remained seated on the case stopping oil from evacuating the case. This stopped the oil messing the gearbox and dripping onto the exhaust pipe. Another trick is to use a light running in oil on a new engine and new rings as it allows the rings to bed in. If you use 50 grade oil, the oil will be pumped out into the exhaust and the rings will certainly not bed in at all. My Comet has completed many thousands of miles since 1982 and does not use oil as you have experienced following the mods that I made. I wish you well from NZ [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Comet Breathers
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