Ok swapped out my stock needle jetting mix to try JD's blue Needle today. History: loved my stock jetting right from the show room floor. because I knew I had to re-jet even the stock setting for my normal ride areas of 4000 ft after one week of bike ownership, I Tried JD's red needle and his smaller jet sizes but was pretty disapointed. The bike lost power I thought in the mid range like it was too lean only pumping air. The 510 when it's running great runs like a sewing machine AND it also has this growl and power drive boost all thru the low, mid and top end. When the bike is running rich it gets muddy, but when its too lean in my experience it may run like a sewing machine nice and clean but it looses that signature power growl as you accerlerate and ....it just becomes a fancy air pumper in my view. so I pulled out JD's red needle and jet mix, and worked the stock needle, simply raised the stock needle clip to 4th and down sized my jets till I got the right mix for 4000 ft 50-70 F which was stock needle at 4th clip ( up one from TE stock 5th clip ) main jet at 180 down one from the stock 185 low speed jet at 50 down from the stock 55. FS at 2 turns that setting worked good and I could set the FS at 1.5 for higher elevations or temps until it got to be 5000 ft yesterday and 75F plus ( the first real warm day this spring) then the bike got muddy and boggy bad quick...so I thought ok time to plan for summer jetting, but before I adjust the stock stuff again, I thought now is the time to try JD's blue needle recomendations Now the history here is after my red needle try, JD asked me to try his blue needle recomendations for the 3-6000 ft range and temps less then 60F.....see the blue needle is richer thru out the range. This made sense to me too as I was convinced that dropping the pilot jet and main jet on the 510 so far 185 to 172 and 55 to 45 I just felt that red needle jet mix made my bike lean clean sounding but gutless air pumper. well today the temps dropped to 50-60, I was ta 4000 ft and with this blue needle set up Blue needle at 3rd clip 45 pj 172mj FS at 2.0 turns The TE-510 was a Tigerrific sewing machine once again! all thru the range, plenty of 510 growling power band and running smooth as silk, but this new mix has uncoverred a new clitch never seen before on my bike. just as you touch the throttle from 0-5% there is a hesitation, a gurgle, bog whatever just as you start hitting the thorttle everytime this gurgle.not really a big bog more a choke like cough....I tried 1.5 turns and 2.5 turns neither helped both seemed to mess up the good thing after the 5% point on the throttle but neither movement of the FS cleaned up this slight hesitation burp as I touch the thorttle which can be a pain in choppy off road stuff where you are on and off the throttle....in the open stuff when shifting I kept up on the RPMs and the bike was running great. darn could this JD blue needle mix be exposing some other issue that my stock needle mix covers over? or do I need just one more adjustment or is it the squirt thing? too much squirt causing it to bog rich as i touch the throttle or is it the opposite this lean hesitation thing like my friend says? can the acclerator pump be adjusted, or if lean down low shall i try a 48 pj? I e- mailed James dean and will let you know his thoughts. anyone recognize my symptoms? so close, yet still far.