Yamaha R6 Forum: YZF-R6 Forums banner
321 - 331 of 331 Posts

·
Registered
Joined
·
38 Posts
I prepared a second set of carbs. Stock needles, 152/148 mainjets and #40 pilots. Stock air cleaner etc.
Part load still very rich - Lambda 0.8 (AFR 12) - response is great.
8k rpm WOT I see Lambda 0.78 (< AFR 12). Higher engine speed around ~0.8.
Ambient temp is around 15°C - so in summer it would be way too rich.

Floater Level I checked and seems ok.
I will check the pilot air jets - forgot this to check, maybe somebody adjusted here something.
I will step back to Pilot #38, mainjet 148 on all carbs and try some different needles (cause I only have 2xN7RA and 2xN7SA).

But I'm still wondering why my carbs are soo rich all time. Air cleaner is new (aftermarket foam type) - for WOT I could understand some impact with higher vaccum but part load I don't understand the difference.
Maybe I have to adjust the floater level - but have to test it.

At the moment I need 1h to remove the carb and reinstall everything... maybe I can improve the time a little bit... haha...
But happy that I see some difference now because too rich costs a lot of power which you can feel at the R6. (2nd gear should lift the front wheel...)
 

·
Registered
Joined
·
362 Posts
The centerline of my scale above is AFR 13 so lambda approx 1 at 13.5k thru 14.5k. Am quite interested in your AF screw setting, I've been interested in tweaking mine but the bike is running well so I also kind of want to leave it alone. If the screws were more accessible I'd certainly mess with them :)
 

·
Registered
Joined
·
12 Posts
Figured i’d post my settings since i’ve been screwing with this for 2 months and have finally found my best settings pre-dyno. It rips hard all the way through redline with no lean or rich spots. I’ve had loads of different input from every post on here and other threads, which helped a ton as the previous owner got rid of the stock air filter. I found most posts difficult to decipher as most of their settings weren’t laid out in a neat format so here you go:

Elevation: 800~ feet above sea level, temperature average lately has been around 45*f.
Fuel: 87 Octane
Air filter: BMC (unsure if race or standard)
Exhaust: Yoshimura TRS Slip-on
Float height: 2.75mm from float bowl mating surface to top of float(might change to 3-3.25 yet like Ivan recommends, no issues like this except when warming up it seems to waste more fuel than it should.)
-EDIT-: Adjusted float levels to 3.15~mm and my fuel wasting issue on warm up is gone.
Main jets: Dynojet 142(keihin conversion: 155)
Pilot Jets: 40 keihin
Pilot AF Screws: 2.5 turns out
Needles: Stock/ 1,4(n7sb) 2,3(n7sa) all needles with 2 (0.5mm) shims each
Crankcase vent tube is not connected to the airbox as it was causing it to run extremely rich, even at my leanest settings. I believe this was from fuel blow by into my oil when my floats were set way too rich and i have yet to change the oil since then.

For dynojet kit, i did not install the air circuit restrictors included in the kit, i basically just ended up using their main jets and shims.

Hope this helps somebody out keeping the 5EB dream alive! 👊
 

·
Registered
Joined
·
38 Posts
When you have your carbs open, please measure some diameters of the needles.
I don't have the U49 spec needles in Europe available. Only N7RA etc. - would be nice to know the difference.
Would expect some leaner running needles.
Tip diameter and straight part diameter (may the position when the tapered starts).

Topham said they used 4x N7RA and blocked main air pilot fo open boxes etc.
I will test it and post some updates when possible.
 

·
Registered
Joined
·
12 Posts
When you have your carbs open, please measure some diameters of the needles.
I don't have the U49 spec needles in Europe available. Only N7RA etc. - would be nice to know the difference.
Would expect some leaner running needles.
Tip diameter and straight part diameter (may the position when the tapered starts).

Topham said they used 4x N7RA and blocked main air pilot fo open boxes etc.
I will test it and post some updates when possible.
Gotcha, the needles are definitely two of each N7SB and N7SA and don’t appear to have any plugs/reducers in the main air jets. I tried running 4x N7SB needles(supposed to only be on outside) but it was causing it to have a bad rich spot around 7-9k, so i went with the two leaner needles again.
 

·
Registered
Joined
·
38 Posts
The N7SA needle I know - it's very rich. N7SB I don't know - that's why I'm asking for some rough measurements.
In the old workshop manual the they mention 4xN7RA needles. Later It changed to the rich N7SA in the middle.
I have to test the Main Air Pilot block.

Before I had the O2 sensor installed I noticed that I have some more power when I close the throttle a little bit.
With O2 sensor I measured Lambda 0,9 at WOT and a little bit closed Lambda 0,86 (perfect on spot...)
 
321 - 331 of 331 Posts
Top