CV Carb setup instructions.
#1
10-14-2014, 02:17 AM
Join Date: Jun 2013
Location: North Texas
Posts: 3,189
CV Carb setup instructions.
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.
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.
Last edited by Klxster; 10-14-2014 at 11:36 PM.
#3
10-14-2014, 05:03 AM
Join Date: Jun 2013
Location: North Texas
Posts: 3,189
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..
#4
10-14-2014, 05:56 AM
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
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
Last edited by Richard Avatar; 10-14-2014 at 05:59 AM.
#5
10-14-2014, 06:15 AM
Join Date: Jun 2013
Location: North Texas
Posts: 3,189
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..
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..
Last edited by Klxster; 10-19-2014 at 02:13 PM.
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