Oil/Gas ratio and gearing ratios

[250Renvy]

So I'm taking my stock 250R w/ a fmf pipe and silencer and putting on a 265 cylinder with a bigger carb and the same pipe.

Is there any way to calculate the ratio of oil/gas to my specifics. I know a lot of people run 32:1. How do you come to the ratio? Right now I run 26:1 based soley on the 20:1 being to rich and just leaning it out until it seemed fine.

Then how do I figure out the best gearing ratio?

Thanks for any help, it'd be appreciated.

[methyman]

Its because back them when the TRX250R was built the oil wasn't as good as it is now. I run Amsoil 50:1 Dominator. The synthetic oil you can run a bigger ratio. Yamaha lube 32:1 and the same with Castor 927. Hope this helps you