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Post by motorhead on Jul 10, 2011 7:07:39 GMT -5
I was working on a GY6 at work changing the belt on it and I got curious and decided to check the gear ratio. I picked a fixed point on the wheel and point on the clutch. I rotated the clutch 8.5 times before the wheel did a full turn. Now... A stock GY6 has 8 or 9 horsepower and does 50-60. a 50cc is geared at 12 or 12 to 1. If you've tuned your 50 to keep up with a gy6 then you've got lots of potential left in your gears.
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Post by jmkjr72 on Jul 10, 2011 8:03:08 GMT -5
zumas come oe at either 13:1 for the 08 to the 11 the 02 to 05 are 14:1
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Post by motorhead on Jul 10, 2011 13:32:59 GMT -5
A stock 50cc is geared at 12 or 14:1 to make use of the small displacement to speedily get it to 40mph where it is geared for. Unfortunetly 12:1 means any speed above 40mph on stock gearing is very inneficient and pulls crazy rpm. Imagine a GY6 8HP 8:1 doing 55 and then imagine your tuned 50cc with 10hp doing 55 at 12:1. Rough math means you need 50% more rpm to do the same speed. That's why a GY6 gets better gas mileage and its motor will last longer than a tuned 50. It does the same speed at 1/2 the rpm. Less rpm = more mpg andmore life. If anything, a gear up kit should be the very next thing done after a cylinder upgrade.
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