View Single Post
Old January 11th, 2019, 12:31 PM   #44
Mohawk
ninjette.org guru
 
Mohawk's Avatar
 
Name: Chris
Location: Bristol, UK
Join Date: Feb 2016

Motorcycle(s): ZZR250, VFR800

Posts: 475
I appreciate this is an old thread but I noticed something missing from the details here. Adjusting the runner length can move the peak torque higher or lower in the rpm range but has very little effect on the area under the curve & it’s a trade off lower rpm torque traded for higher rpm hp or vice versa.

The total runner length is measured form the entrance to the runner which includes the velocity stack, carb or throttle body, the isolator & the head port to the back of the intake valve. Easily measured with a flexible steel rod with the throttle held open.

Pods usually destroy the air feed to the intake. All I takes should begin with a velocity stack this can be just a rolled lip to the carb or TB intake, it should a minimum radius of 6mm (1/4”) to ensure smooth flow in to the intake. Any pods should be mounted forward of this lip & be significantly wider, to ensure clean air flow.

Tapered velocity stacks produce a wide pulse response in rpm terms, straight ones produce the highest pulse tuning effect, but it’s only at a very specific rpm, and produces less effect than a tapered one outside that sweet spot rpm.

As always YMMV
Mohawk is offline   Reply With Quote