avNow version 1.0, plates are spaced at 1/3 & 2/3

Link to the avNow writeup on ThumperTalk.com

avNow version 1.0, the carb side view (with glue)

avNow version 1.0, the air box side view (before glue)

avNow version 1.0, the top view

avNow version 1.1, plates are spaced at 1/4 & 1/2

avNow version 1.1, the carb side view

avNow version 1.1, the air box side view

avNow version 1.1, the side view

avNow version 1.2, plates are spaced at 1/4, 1/2 & 3/4

avNow version 1.2, the carb side view

avNow version 1.2, the air box side view

avNow version 1.2, the side view

avNow version 1.2, the bottom view

Dyno tests

I dyno tested the avNow vs. the stock venturi for my WR250F with the FMF PB SX and stock silencer uncorked. I asked the guy (he races and tunes street race bikes with the DynoJet machine so he knows his stuff) about the HP and why it isn't as high as I've seen (i.e. in the upper 20s and low 30s) - he said don't believe the hyped up numbers, look at the curves.

So I'm looking at the curves for where the torque and HP differences are and it's hard to see because the printout lines are so small it was hard to pick up with my scanner but if you look closely, you can see the red line is stock, blue line is the avNow version 1.2 and the black line (which I had to pencil in because the green wasn't showing) is the avNow version 1.0. You can see obvious gains in HP and torque for the avNow version 1.2 over stock in the low to mid RPM (i.e. 4K to 7K RPM), yet version 1.0 (with shorter tongues at 12mm vs. 14mm for version 1.2) shows a strange curve (worst than stock?) - it is pretty weird looking at the graph when I know I can feel the difference down low to mid with both version 1.0 and 1.2.

The fuel mixture graph also shows that I was running way too rich in the middle and slightly rich in the upper RPM - he told me if my jetting is better, i.e. leaner, my bike would be registering better curves. He told me to drop my needle one to two clip positions (I dropped it one clip position to #2) and perhaps lower my main jet from 178 to 175 if it's still running too rich after dropping the needle. I dropped the needle and it seemed fine with me so I'd rather run it slightly rich than lean. I asked him about the fuel mixture screw and the PJ and he said those are mostly for the idle circuit and my bike is idling really well already so I should leave that circuit alone.

So you can see there is a very slight loss in HP up top (0.3 HP & 0.2 ft-lb) but a larger gain down low to mid as suspected from my "seat of the pants" feel (almost 1 HP & 2 ft-lbs). Keep in mind that with the original PowerNow, I had no feeling of the power gain down low, yet it worked real well on the tracks/trails with starting, stall resistance and pulling higher gears so with the avNow, I'm getting the same characteristics as the PowerNow but I've also gained torque, HP and I'm doing wheelies much easier :-)

Conclusions

This is my setup: YZF timing FMF PowerBomb SX head pipe Stock WR silencer, typically with Vortip, sometimes with baffle removed 12T CS sprocket (stock was 13T) with 52T rear sprocket 178MJ (stock was 175) and stock 40PJ Fuel screw at 2 turns out (stock was 2 1/4) Needle clip at position 2 (stock was position 3)

Version 1.0: Revved the fastest & smoothest with the above jetting setup but has slightly less punch down low to mid (i.e. the difference was hardly noticeable). Easiest version to make.

Version 1.1: Better punch down low to mid versus version 1.0 but throttle transition from low to WOT was not as fast or as smooth as version 1.0 - slight bogs probably due to the change in the induced air pressure right at 1/2 throttle.

Version 1.2: Similar punch as version 1.1 down low to mid but smoother transition from low to WOT compared to version 1.1. Hardest version to make (tripple plates).

avNow version 1.2, after 320+ miles, subframe raised

avNow version 1.2, after 320+ miles, close up 1

avNow version 1.2, after 320+ miles, close up 2