The difference of overall weight is minimal, but the difference of that rotating mass 2" from center on the end of the crankshaft is worth reducing if you can, especially considering how hard most disc clutched lock up and the amount of crank flex some of these clones are seeing.
Single disc Bully would be my preference.
Is it a big advantage? -- In performance, sure, but once the clutch is locked up 1:1 (or nearly), it will make no difference at all what clutch you have on there. So, for starts and restarts you could justify it for sure. Beyond that is up to your driver. With all of these little ones racing, it's generally more about seat time than optimizing performance.
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Thanks and God bless,
Brian Carlson
Carlson Racing Engines
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32 years of service to the karting industry ~ 1Cor 9:24
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