So after getting an 1980 XS650 last year that had a lost title and a plethora of issues, I am finally on the road this summer and fall. So far its been an awesome bike but I am finding that my carbs may need a bit of an upgrade / adjustment. I have the BS34's with pod filters and a 2-1 exhaust. I'm noticing that around 4k - 5k rpm that the bike seems to stumble a bit and hesitate but then gets out of it and revs up the rest of the range fine. I'm wondering if this is due to the fact that I haven't upgraded either of the jets in the carb. The ones in there now are a 135 main and 42.5 pilot which i believe is stock. So I was wondering what jets I should go with to get rid of this problem and have a little better performance? Should I go with the Heiden Dyno Tune Needle & Jet Kit? Or just upgrade the jets to a different size? All input is appreciated!