Odd, I just today fitted Pro Taper bars to my 2009 klx and fitted 20mm bar risers and the clutch cable seams fine. I was thinking i might actually fit 30mm risers as I think i could go further.

 

When I installed my cable I just used vice grips to turn the shaft on the housing to allow me to get that end of the cable in. Works perfect and i still have enough cable adjustment.
If that makes sense lol.

 

Not saying what I did was right, but it was in a dark parking lot...
I attached the cable at the handlebars and then pulled the clutch to meet the other end.
In my haste I actually pushed the clutch rod assembly thingy too far and got it stuck. Managed to get it back applying some brute force, then attached the cable, since I wasn't smart enough to do it when I had the rod stuck and more than enough slack to attach the cable in that position.

So to the OP, did you get it figured out?

Did your new cable come with an adjuster barrel in the middle? Might get some more slack for the housing there, which effectively lengthens the cable.

 

Thanks for the help guys!

I ended up borriwing a pipe wrench which I was able to use for leverage. Once it was in place there was more room then expected.

Managed to take it out for a quick spin.

 

Got snow? LOL.
Glad you got it fixed.

 

Making your own doesn't seem all that difficult. I found this Cable Parts - Cable Kits and Parts - Products | Venhill USA while searching for longer cables.