Hope this helps those that are interested.


CV Carb Tuning Procedures

AFR Values & Characteristics in Four Stroke Engines
6.0 AFR - Rich Burn Limit (engine fully warm)
9.0 AFR - Black Smoke / Low Power
11.5 AFR - Best Rich Torque at Wide Open Throttle
12.2 AFR - Safe Best Power at Wide Open Throttle
13.3 AFR - Lean Best Torque
14.6 AFR - Stoichiometric AFR (Stoich)
15.5 AFR - Lean Cruise
16.5 AFR - Usual Best Economy
18.0 AFR - Carbureted Lean Burn Limit

My dyno testing indicates that ,when near sea level, we cannot get anywhere close to 12.2:1 (not to mention 11.5:1) with slip-on, lid off, and DJ kit - even using #132/4th notch down on the needle.

 

That's some good info!

Anyone have success using a set up to monitor A/F ratio while riding?

 

Yes actually. Richard Avatar is doing it now. He has welded a bung on his header and is testing jetting while riding.. Yall should start PM'ing him to start posting his findings - he needs a little coaxing to start posting..

 

No need to send PMs, I'll post results as I go along.

In a few minutes I am going to take out the P6 needle jet and replace it with the P4 on my 36mm carb to try and lean the steady 11.6-11.8 a/f ratio I was getting throughout the rpm range yesterday a bit. The 9EBY1-50 needle that's in it seems to be a very accurate taper; props to all those who sorted this stuff out before me. I just need to try a little leaner since it's so easy to know what a change has done with the magic box hooked up.

I guess I am in the "rich torque" range right now. Not bad if you want some extra cooling, and it pulls great.


I have to say the throttle back off at WOT technique seemed to work very well getting my this close just by seeing if the engine speeds up (lean) or coughs/burbles (rich) when reducing to 7/8 throttle from WOT

 

If the chart and info are to be trusted, going toward 12.2 to 12.5 may create more power over mid/upper 11's....

We can't get anywhere near that rich with the CV/DJ kit.. I wonder how much more power is there waiting with only a larger main jet (DJ#134, DJ#136, etc) in the CV..