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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Compression ratio choice
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<blockquote data-quote="timetraveller" data-source="post: 5293" data-attributes="member: 456"><p>I agree. Stick to the 9:1s. If you want to reduce to 8:1 you might find it more tractable in traffic but it is completely the wrong thing to do to use compression plates as you end up with an inefficient combustion chamber shape. Better to change the pistons before you use them if you really want to go lower.</p><p> </p><p>Regarding kick starting; I am continuously appalled at some of the ways I see people starting their bikes. They fiddle around with the valve lifter and gently turn the engine over until they think that they are on the cylinder with the longest dwell before it fires. They then let go of the valve lifter and try to kick the engine over against the compression, hoping that they have enough momentum built up by half way down the stroke of their kick. No sir. Prime your carbs or use the chokes or whatever you have, turn the engine over gently with the kick starter a few times to get the oil started on its journey, then turn on the ignition, unless you still have a magneto in which case it is already on and the slow turning of the engine will have prevented it firing, then with the valve lifter lifted, kick down and half way down the stroke let go of the valve lifter. That way there is no fiddling about trying to find the correct position of the engine. You have lots of inertia built up because there is no resistance to the turning of the engine and hence the kick starter and you have given the whole kick starter mechanism a much easier time of it. Trying to boot the engine over against compression might be good for your right leg muscles but it is an abomination for the kick starter mechanism. If the bike does not start first or second kick with the above approach then there is probably something wrong.</p><p> </p><p>Be gentle with it and it will serve you well.</p></blockquote><p></p>
[QUOTE="timetraveller, post: 5293, member: 456"] I agree. Stick to the 9:1s. If you want to reduce to 8:1 you might find it more tractable in traffic but it is completely the wrong thing to do to use compression plates as you end up with an inefficient combustion chamber shape. Better to change the pistons before you use them if you really want to go lower. Regarding kick starting; I am continuously appalled at some of the ways I see people starting their bikes. They fiddle around with the valve lifter and gently turn the engine over until they think that they are on the cylinder with the longest dwell before it fires. They then let go of the valve lifter and try to kick the engine over against the compression, hoping that they have enough momentum built up by half way down the stroke of their kick. No sir. Prime your carbs or use the chokes or whatever you have, turn the engine over gently with the kick starter a few times to get the oil started on its journey, then turn on the ignition, unless you still have a magneto in which case it is already on and the slow turning of the engine will have prevented it firing, then with the valve lifter lifted, kick down and half way down the stroke let go of the valve lifter. That way there is no fiddling about trying to find the correct position of the engine. You have lots of inertia built up because there is no resistance to the turning of the engine and hence the kick starter and you have given the whole kick starter mechanism a much easier time of it. Trying to boot the engine over against compression might be good for your right leg muscles but it is an abomination for the kick starter mechanism. If the bike does not start first or second kick with the above approach then there is probably something wrong. Be gentle with it and it will serve you well. [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Compression ratio choice
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