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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Dual spark dethroned
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<blockquote data-quote="davidd" data-source="post: 50131" data-attributes="member: 1177"><p>I am not sure that I am smart enough to know. 32 degrees sounds just right to start. I would guess that because there are no improvements to the combustion chamber that the single spark might like 32 more than 28, but 4 degrees is not a huge jump. If the single spark completes its combustion work in 32 degrees it will make the most power there. If it can finish in 27 or 28 degrees it will show more power because the peak pressure in the cylinder will occur 4 degrees too early and the pressure may even peak prior to TDC. Usually, peak pressure should be at 12-14 degrees after TDC. So, when we set the timing we are looking through the wrong end of the telescope. We are really trying to guess where we can light the spark so that will in turn create maximum pressure at 12 ATDC. Not easy when you have all the variables of compression, exhaust, inlet changes as well as fuel and atmospheric changes. </p><p></p><p>That being said, getting the maximum power with a either a single spark or a dual spark will give you a nice ride. </p><p></p><p>David</p></blockquote><p></p>
[QUOTE="davidd, post: 50131, member: 1177"] I am not sure that I am smart enough to know. 32 degrees sounds just right to start. I would guess that because there are no improvements to the combustion chamber that the single spark might like 32 more than 28, but 4 degrees is not a huge jump. If the single spark completes its combustion work in 32 degrees it will make the most power there. If it can finish in 27 or 28 degrees it will show more power because the peak pressure in the cylinder will occur 4 degrees too early and the pressure may even peak prior to TDC. Usually, peak pressure should be at 12-14 degrees after TDC. So, when we set the timing we are looking through the wrong end of the telescope. We are really trying to guess where we can light the spark so that will in turn create maximum pressure at 12 ATDC. Not easy when you have all the variables of compression, exhaust, inlet changes as well as fuel and atmospheric changes. That being said, getting the maximum power with a either a single spark or a dual spark will give you a nice ride. David [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Dual spark dethroned
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