Quote:
Originally Posted by JacRyann
The factory jetting on a newgen bike is both too lean AND too rich. Lean in low/mid-range and rich in high-end. Easiest to address each range individually:
1. idle & low-end - unscrew pilot-screws 1/4-1/2 turn more than factory setting
2. midrange - shim needles 1-4mm, 1mm at a time. This is the variable depending upon which slip-on you get.
3. high-end - get smaller main jet, two sizes down if you have factory exhaust. One size down with aftermarket exhaust
I've got 20% more high-end power than stock on my 2008. AFR is spot-on at 13.5:1 for maximum power in high-end (compared to stock 11.5-12.0:1). To do that, I went down to slightly smaller main jet with Tyga full-exhaust. Or just leave factory main-jet alone for 13.0:1 AFR in high-end. This is real tried and true mods done by pretty much all racers on newgens. I can dig out dyno-charts and magazine-articles that showed this is path to enlightenment. 
EDIT - > REFERENCES
Racing on the Cheap - scroll down to "The Nuts and Bolts" section, note: "close to perfect" is with full AreaP exhaust and factory jetting.
Racing Order - Dyno testing
Dyno testing - lean mid-range only - thinned needle to correct. |
Thanks for the detail, I’ll have to do a little bit more research before I tackle the carbs.