Carb tuning take 2 - AEM wideband info & has ANYONE adjusted float height?

[rwheelz]

Continued from my original tuning thread here:
http://www.ninjette.org/forums/showthread.php?t=65881

Current setup:
Factory Pro jet kit
K&N pods 0990
KLEEN removed
TYGA full exhaust
110 Mains, FP 40 Pilot, needles at position 2, idle screws at 1.25 turns out, float height untouched, 3800 ft altitude.

I drilled out the O2 sensor bung on the Tyga exhaust so the bosch sensor would fit (AEM wideband) and I could finally get some A/F readings. I am happy with the way the bike feels for now, but am convinced it still needs some fine tuning. It feels strong except for the low end, where it runs very rich and bogs a little compared to the rest of the powerband.

Monitoring the A/F while riding is a little difficult. I wish I could datalog, but I would need the laptop on the bike with me. I mounted the AEM gauge above the key in front of the factory gauges and was able to do a lot of runs where I could glance between the tach and the AEM.

The A/F is reading in the high 12s-low 13's for most of the powerband. These are all WOT readings.

Top end: Interestingly, there is a lean spot in the powerband from 9,500-11,000, where the A/F creeps up into the mid-occasionally-upper 13's, then drops back down. I am not sure how I would fix this, since putting in larger mains would make it excessively rich above 11k (it is already mid 12's up there as well as below 9,500).

Mid range: from 4500-8500 it is running ~12.8 and is smooth.

Low end: from 2000-4000, the bike is still too rich. The idle is perfect, no bogging or hanging when blipping the throttle, but trying to pull WOT in this range puts the A/F in the 11's. I am convinced I need to adjust the float height after reading the FP tuning instructions (as well as any tuning info I can find on this forum) several times. I cannot find any threads where people talk about adjusting the float height (please chime in if you have played with this).

Part-throttle: At VERY light throttle, the bike is pretty lean. I am talking just barely causing it to accelerate. It is reading in the 15's. Slightly more throttle input, and it reads high 13's. While holding a steady speed, there is no surging or any hiccups.

Can anyone else who is monitoring A/F ratios contribute their results?

Future plans for the bike: We did baseline dyno runs with the bike completely stock. We plan to run it again in a month or so. If I decide to adjust the carbs before then, I am also going to drill the slides according to the DIY thread. I would like to adjust the float height, and will probably order the FP gauge. For now, the bike feels great and I don't want to ruin a good thing!

[randomwalk101]

Very nice. Are you hooking up that AF gauge permanently? I'm thinking of getting one myself too?

[Lvr]

I haven't played with an A/F, but I did mess a bit with the float height. It was originally at about 16.5 mm, I lowered it by 1 (to richen) and then raised it about .5 (to lean) so ended up at 16mm. It definitely had an effect, although it turned out the problems I was trying to correct were more to do with the pilot jet.
Bending the little tab is easy if you have a typical pair of needlenose pliers. I believe you push the tab in to richen/lower float height, and grip it with the pliers to pull it out. Tiny movements have a pretty big impact.
The other tip is that the tab compresses a two part switch. I don;t have any pics of it, but if you look closely at it you'll see there's a larger metal cylinder with a tiny nub poking out of it. As near as I could tell, when you measure float height you want the larger base cylinder compressed but not the nub (the float spring according to the Factory Pro guide). That means you hold the carbs sideways. I used a regular set of calipers to measure it, nothing special.
Hope that helps!

Edit: after reading your post more carefully, I would strongly suggest (based on my experiences) that you try replacing the #40 pilots with #38s (stock). I had richness in the 2-4k range as well; switching the jets and putting the mix screws at about 2.7 turns out fixed it. The floats, when I adjust them, seemed to have more of an effect on power around 3-4.5k, but not so much the very low end. Just my .02.

[rwheelz]

Thanks for the advice! I was wondering if the pilot jets are too rich. I think maybe I need to switch the pilot jets AND adjust the float height a little.

I am using the wideband to tune, but am not leaving it installed permanently. I want to use it to tune my 9R as well, and the sensor takes up a LOT of the cross-sectional area of the small Ninjette exhaust pipe which doesn't seem ideal.

[kkim]

Originally Posted by rwheelz

I think maybe I need to switch the pilot jets AND adjust the float height a little.

maybe, but remember, the accepted jetting fine tuning approach is to only make one change at a time to see what changes as to not be confused with the results.

[rwheelz]

Originally Posted by kkim

maybe, but remember, the accepted jetting fine tuning approach is to only make one change at a time to see what changes as to not be confused with the results.

Good advice! I will definitely do that.

[randomwalk101]

let us knows how it goes...i'm in the process of drilling & installing the bung for that aem a/f