Porting and polishing an otherwise-mostly-stock KLR650 engine?
You stand on the precipice of an abyss of severe diminishing returns, as in benefits far less than the effort obtaining them, IMHO.
Porting and polishing, according to conventional wisdom, is among the LAST hop-up options, in contrast to the FIRST. Only a highly-modified engine can benefit within any economy-of-scale from porting and polishing.
Don't know your definition of, "Throttle Response." If the term means the time interval between twisting the handgrip throttle open and the opening of the carburetor slide, porting and polishing has zero, nada, zilch, zed effect. A slide (versus a stock CV) carburetor offers improved throttle response within this context, but sacrifices some CV versatility characteristics (an accelerator pump on a slide carburetor compensates somewhat for this loss).
And . . . as posted above, it's a KLR! Sub-40 horsepower; even highly modified; hardly a David to slay the Goliaths (e.g.
, KTM690; nearly 70 hp out of the box).
Yet, we've all seen, "The World's Fastest Indian" movie! Keep in mind, the title motorcycle was essentially purpose-built, involving years of effort, tens of thousands of dollars, and, I think, a DIVORCE!
DISCLAIMER: Above post contains my often-ridiculous opinions, only.