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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Twin Plug Heads - Better or No Difference?
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<blockquote data-quote="davidd" data-source="post: 117508" data-attributes="member: 1177"><p>Glad to take a shot!.</p><p></p><p>I think that I have been consistent about saying that the twin plug conversion on its own does not cause any increase in power. I would note one side effect that some (like Stuart Hooper) have found extremely useful: better starting. That advantage alone might make twin plugs beneficial to the bike. This is in line with what Stu mentions: side effects like better fuel mileage and better starting are often very useful.</p><p></p><p>As for power gain, most of the power gained by changing to twin plugs comes from being able to use a much more efficient spark timing. This is because the earlier the spark occurs (say in the 30 degree area) the more the spark is slowing the piston just before TDC. If the spark can be moved to the teens or low twenties then almost all of the energy of combustion is used on the power stroke. That can be a noticeable power gain.</p><p></p><p>All of this has to happen together. The ports have to be efficient and the combustion chamber has to be small and efficient (usually with squish) to work well. Most modern tuners want twin plugs because they provide the platform for additional tuning.</p><p></p><p>Ted is most likely correct. I think a side by side comparison of dyno runs with no other changes will yield the same results.</p><p></p><p>David</p></blockquote><p></p>
[QUOTE="davidd, post: 117508, member: 1177"] Glad to take a shot!. I think that I have been consistent about saying that the twin plug conversion on its own does not cause any increase in power. I would note one side effect that some (like Stuart Hooper) have found extremely useful: better starting. That advantage alone might make twin plugs beneficial to the bike. This is in line with what Stu mentions: side effects like better fuel mileage and better starting are often very useful. As for power gain, most of the power gained by changing to twin plugs comes from being able to use a much more efficient spark timing. This is because the earlier the spark occurs (say in the 30 degree area) the more the spark is slowing the piston just before TDC. If the spark can be moved to the teens or low twenties then almost all of the energy of combustion is used on the power stroke. That can be a noticeable power gain. All of this has to happen together. The ports have to be efficient and the combustion chamber has to be small and efficient (usually with squish) to work well. Most modern tuners want twin plugs because they provide the platform for additional tuning. Ted is most likely correct. I think a side by side comparison of dyno runs with no other changes will yield the same results. David [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Twin Plug Heads - Better or No Difference?
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