Choices are Large Hex, Small Hex, Large Round, or Small Round. I am guessing Small Round?

This is for a buddies 03 or 04 Scrambler 500. He has a white bros slip on and K&N filter. I figured I'd start with a 160, sound good? Thanks!

 

155 is stock and there a little fat from the factory.

 

yeah i would start with a 160... u can always go from there

 

Hey, thanks for the replies. I did more searching and found that they are, in fact, the "small round" type.

 

He may be able to get away without rejetting. Let the plug be the judge of that. But, if it is running a little lean, a 160 main jet and the air/fuel screw about 2 turns out from seated should do the trick