Forget about jet kits. VERY LITTLE (if any) improvement in performance for the CVK34 from such modification, IMHO.
Rather . . . disassemble, clean, inspect, and adjust the stock carb. Take a close look at your diaphragm fabric condition and sealing upon reassembly; an air leak here can cause "bogging."
A properly adjusted and cleaned stock carb won't "bog," nor will a jet kit cure the condition if it does.
My opinion only; opposing views welcomed!
FULL DISCLOSURE: 2003 KLR650, all stock, runs like the wind!
Seeking clarification, not entirely sure of the meaning of the expression, "bogging under throttle." The little 250 is, a little 250. It must rev high to process the fuel necessary to produce meaningful power. Three grand's about a minimum riding speed, seems to me, and the thing doesn't REALLY come alive 'til 6000.
I got mixed up in a pack of BMWs on a loop at a rally in West Virginia; I was shifting at 9,000 rpm to keep those guys in sight!