Jetting changes; switching from C12 to U2

MarkSims

Member
Feb 9, 2004
87
0
I have an Eric Gorr KX310 and I've run C12 in it from day 1. I'm going to try U2 this weekend so I'm taking my best guess at how to modify the jetting. Currently, I'm jetted well - definitely not rich anywhere.

I couldn't find a spec on vpracing's website that gives the % of oxygenation in the U2. I went up 1 size on the pilot and moved the needle clip down a notch.

I went up 1 size on the main - and I'm starting to wonder if that wasn't enough. Anyone have any experience with U2?

Rich? :worship:

Thanks! Mark
 

steve125

LIFETIME SPONSOR
Oct 19, 2000
1,252
0
Mark the U2 and U4 are 6% O2. The steps you have made are in the right direction. Maybe 1 size larger on the main to be safe and then check your plugs fuel ring after a WFO throttle chop. Your pilot setting if correct will be determined by your air screw setting, 1.5 out being the optimum setting. Below 1 out use a richer pilot, past 2.5 lean it out 1 size. This fuel jets in real easily and makes power when done correctly, it also has a super throttle response! Expect a 1-2 hp gain mainly on the top end. :cool:
 

MarkSims

Member
Feb 9, 2004
87
0
I ended up going 2 steps richer on the main, 1 on the pilot, and 1 on the needle clip. The bike ran very well. It wasn't a huge difference, more like the bike was just running very well - very smooth. I'm going to stick with the U2.
 
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