As a general rule of thumb for raising transfers.If the design has them opening @ 118deg ATDC with an exhaust set @ 88deg ATDC,This would be suited for "enduro" type power- wide torque .Most euro bikes have this set up.
If you raise the opening timing to lets say 116deg and leave the exhaust alone the power will be even flatter on top with a moderate gain from 3500 rpm -5600 rpm.If you raise the exhaust and transfer timing to lets say 84 deg and 116 deg then a slightly narrower power band with a much higher rpm peak is the result
If the transfers are too big or too small to begin with then cylinder filling capibilities are a big problem.These issues influence the power output the most.
As with most 2 cycle designs go ,the many comprimises that have to be made so most people can ride them can cause a good bike to be a pile once it hits the dealers so keep in mind that relative small internal changes might show no gains or loses at all.
There are many SEA papers written to clarify this.
And as many ways to skin the same cat.
Keep in mind the easiest way to raise ports is with gaskets
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