if you go open filter the cp carbs will be the ticket. you still wont want it any bigger than 16-17mm. the cp carbs are setup for open filters.
i didnt realize there were stock clutch springs but anyway they just slip more.... they are a pain to install / and overheating the clutch is no joke. use at your own risk.
i see no point in clutch springs for your future. it will pull so hard as it is. just try it stock.
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the dynos are handy but the writers have issues with a number of things. my biggest beefs are the hp readout instead of kilowatts. if you want to look at dynos the is some good ones for piaggio that explain how nothing can beat the yasuni z untill you go to midrace and change every part available. even then the torque is the same but the rpms go UP
--- on piaggio the z is king and the r is a tuners pipe