Thread: New rider.
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Old May 9th, 2018, 12:22 PM   #18
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: Mesa, AZ
Join Date: Dec 2011

Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
Hi and Welcome!

Quote:
Originally Posted by NinjaRacer View Post
HI.
I got 110 keihin main jet and it was bogging down at 8K. I'am on 98 again and 2 washers it runs much better.
Please note that optimum jetting for new-gen vs. pre-gen bikes are >> COMPLETELY << different. This is due to differences in tuning with pre-gen optimised for high-end power while new-gen for mid-range torque. Cam-specs are different, head port shapes are different, exhaust are 2-2 versus 2-1. This creates completely different flow-pattern from idle to redline. Jetting for pre-gen will not work for new-gen.

When dealing with jetting changes, look for before-and-after dyno-charts to verify what changes it made to AFR in what RPM-ranges. Here's some reference articles:

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 full AreaP exhaust - still too-rich high-end, lean mid-range only - thinned needle to correct.

Last futzed with by DannoXYZ; May 10th, 2018 at 08:59 AM.
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