Testing the 34mm CVK with a/f meter
 

I went ahead and reinstalled my CVK 34mm to see how the a/f numbers looked:


The jetting that was in it is the popular N1TC needle with clip in the middle and a 135 main jet.

First outing saw everything rich. Part throttle positions and WOT were 11 or below ( hi10s)

So I came back and put in a 132 main and raised the clip one notch to second notch from the top (leaner)

On the second outing, now with the 132 main and the leaner needle clip location, part throttle readings went to 13s with a 14 now and then as I accelerated around at various throttle positions, but WOT was a steady 11 flat.

I wanted to put a 128 in it, but all I had was a 125 and a 130. I didn't think the 130 would be enough of a drop from 132 to change that 11 flat to a better number, so I put the 125 in it and the WOT a/f numbers are good enough-in the 13s, with 14 flashing briefly-maybe on the speed shift.



That's quite a drop in main jet size from that 135, but that's the readings I am getting. I have to order some pilot jets anyway, so I'll order a 128 at the same time. But the WOT isn't bad now; it should be making more power now that it's not so rich.

I'm less concerned with fretting over 13.25 vs 13.75 a/f numbers than I am just getting a number within a good parameter. For my purposes the a/f meter has let me see how far off the jetting was even though the bike seemed to run fine when it was so rich.



I calibrated the a/f meter to ambient yesterday morning, so it should be accurate.


:shrug:

Reading another recent thread I see KLXster promoting the 132 main jet near sea level, and I'm at 100' ASL. Off hand, I'd say the bike may have felt quicker today with the 132, but I wasn't really trying to sense power while testing, just watching to see what the a/f meter did.

Just a slightly nagging ? in my mind afterwards.

As I mentioned above, I got solid 11 flat WOT a/f readings with the 132; it doesn't seem to be a mix that would yield more power.

My 07 bike ran a lot better with a 125 and the same needle than my 09 with DJ132 and needle 1 clip richer

The DJ needle and main jets do not compare to other brands (E.G. Keihin).
Richard, I don't know what components your testing - All I have to test are DJ components in the DJ kit on a new CVK34 carb.
During 3 dyno sessions spread out over several months, the AFR charts were consistently lean. The best I was able to do was with the largest main in the kit (DJ132) and needle on 4th notch. That chart (Posted in my exhaust shootout thread) is self explanatory. Stock header + Slip-on only went down to 13.5 . Then I find out from DJ that the kit is not designed to work with the lid off and that lean AFR's are to be expected.
It may be that going outside DynoJet components (N1TC needle + Keihin main jets) is a better/cheaper avenue to getting these AFR's correct at WOT.
In the mean time, all I can do is try to get the word out to those running standard Stage 2 ( DJ128, 3rd notch ) that there is more power, near sea level, with the DJ132/4th notch.
I can only hope to get WOT AFR's down around 12:1 with larger DJ mains - which will arrive soon.

Richard,
Can you specify if you're using Keihin or DynoJet jets, and the state of your air box lid (on/off/snorkel)? For example, a #125 Keihin jet is close to a #118 DynoJet.

https://www.kawasakiforums.com/forum...e2/#post442610

I am using genuine Keihin small round head jets that I originally ordered for my XR200 (which also uses Keihin carbs)

I'll put the 130 in it and see where it's at next time I have that carb on the bike. Using 10% ethanol requires slightly richer mixtures; 12.2 for max power, so maybe the 130 will raise my WOT a/f up from 11 flat to nearer 12.2.

No lid or backfire screen, drilled air box, K&N filter, straight thru muffler with an inlet OD that's larger than the header/mid pipe OD as the rear half of the mid pipe expands to a larger size.

I saw you mentioned that in another post previously. The 125 is a little lean but still in the acceptable range.

There could be factors influencing the a/f to where my results aren't the same as others with similar mods. Maybe the megaphone style mid pipe is drawing gases out from the cylinder better and sucking harder at the carb as a result. I think it goes from 1.5 OD at the header connection to 1.75 OD at the muffler.


http://static.wixstatic.com/media/ba...0_0.00_jpg_srz


I fabbed up a rudimentary air flow bench years ago using a shop vac, clear tubing with colored water, and graph paper behind it. Along with a vacuum connection perpendicular to the exhaust pipe. You could see the back pressure drop significantly when rolling some stiff paper into a megaphone shape and butting it up against the end of the long open header.

Assuming the jet comparison charts are correct, the N1TC needle must be the variable. Apparently it is quite a bit smaller in diameter than the DJ needle @ WOT .

Exhaust does change the AFR curve for a given carb tune - in my exhaust shoot-out, the full FMF was much richer than stock header+DG-R from 4k to 6.5k RPM.

Zomby, It looks like the N1TC + 125 produces about the same AFR @WOT as the DJ132/4n. I'll bet that N1TC needle offers better performance than the DJ.

That's quite interesting.
I think it goes to show how small setup differences can make a surprisingly large impact on jetting, and how all bikes are not the same. You're running a 128 or 130 Keihin. Klxster is running the equivalent of approximately a 142 and will be trying a 145 or 148 Keihin size. You're both at or near sea level and tuning with instruments to optimize a/f ratio. One size does not fit all!

It shouldn't. There's a huge difference in jet size between a 125K and a 132DJ. I believe the DJ is the equivalent of 8 jet sizes bigger.