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Aftermarket Engine/Parts
Lifan
New 125 Sputters through all throttle/idle
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<blockquote data-quote="69ST" data-source="post: 181652" data-attributes="member: 5"><p>Having the mph/1000rpm number is pure gold, for a tuner. Having the numbers OLD CT gave, for this engine Trailwing tire size combo is, as well. If your current combo has been tested & works well...and you know the engine rpm at any given speed...that's even better. All you have to do is work with percentages, based on tire sizes.</p><p></p><p>The simple answer to your gearing question is: there is one optimal sprocket combo with ~6% spread (+/-3%) to accommodate rider preference, that's it. Usually, I'm digging deep into every imaginable scenario & situation. Gearing doesn't need all the longwinded explanations. The engines power curve determines optimal gearing, period. You are torque limited and that's that. </p><p></p><p>I learned how to dial-in gearing about the time when the first silver CT70 K0 model rolled off the line. It comes down to basic physics. With these little bikes, what matters most is getting the final drive (top gear) ratio right (crankshaft-to-wheel) based on what the engine can pull without falling on its face in top gear. Believe me, with just a bit of experience, you'll know when that point has been reached. With this level of engine output, that happens when you're ~3.5% overgeared, in absolute terms. Once you get that sorted, the rest of the gear ratios take care of themselves. The engineers did get the overall ratio spread (first gear to top gear) right. It even translates from road to trails. The only exception I've found is super low-speed riding with lots of stops & starts...like a swap meet. An engine can only pull so much gear (torque) and deliver so many mph (horsepower). Carburetion is a totally separate parameter, that needs to be dialed-in the same, regardless of operating conditions; any "adjustments" to riding style are, well, throttle application.</p><p></p><p>That's all, folks! Stick to this and you'll have your bike run optimally in no time...and...it only has to be done once.</p></blockquote><p></p>
[QUOTE="69ST, post: 181652, member: 5"] Having the mph/1000rpm number is pure gold, for a tuner. Having the numbers OLD CT gave, for this engine Trailwing tire size combo is, as well. If your current combo has been tested & works well...and you know the engine rpm at any given speed...that's even better. All you have to do is work with percentages, based on tire sizes. The simple answer to your gearing question is: there is one optimal sprocket combo with ~6% spread (+/-3%) to accommodate rider preference, that's it. Usually, I'm digging deep into every imaginable scenario & situation. Gearing doesn't need all the longwinded explanations. The engines power curve determines optimal gearing, period. You are torque limited and that's that. I learned how to dial-in gearing about the time when the first silver CT70 K0 model rolled off the line. It comes down to basic physics. With these little bikes, what matters most is getting the final drive (top gear) ratio right (crankshaft-to-wheel) based on what the engine can pull without falling on its face in top gear. Believe me, with just a bit of experience, you'll know when that point has been reached. With this level of engine output, that happens when you're ~3.5% overgeared, in absolute terms. Once you get that sorted, the rest of the gear ratios take care of themselves. The engineers did get the overall ratio spread (first gear to top gear) right. It even translates from road to trails. The only exception I've found is super low-speed riding with lots of stops & starts...like a swap meet. An engine can only pull so much gear (torque) and deliver so many mph (horsepower). Carburetion is a totally separate parameter, that needs to be dialed-in the same, regardless of operating conditions; any "adjustments" to riding style are, well, throttle application. That's all, folks! Stick to this and you'll have your bike run optimally in no time...and...it only has to be done once. [/QUOTE]
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Lifan
New 125 Sputters through all throttle/idle
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