[BeakersWorkshop]

My new to me bike has been running really rich and I got tired of farting around. I have a 658 with stock exhaust and airbox mods.
Temporarily put a AFR (Lambda/UEGO) gauge onto the bike to see what is going on. So many seat of the pants info and dodgy "info/recommendations" (Bike Specs at the bottom below the images).


Alt: 1050M (3400')
Dyno Jet Kit. C-Clip on 2nd notch of needle.
40 idle Jet, 2 turn out
Keihn 145 Main Jet (the DJ orifices are wayyy too big)

Results:
Idle at 14.5 (nearly Perfect)
Cruising at 12.2 to 13 (Little Rich, Ideally its closer to 15.5ish)
Acceleration 11.5 to 12ish (no change with WOT at full load, Maybe a bit rich).

Next time the Carb is out or I have the tank off I will move the clip to the fist position)

2008, 65k on the ODO
685 Kit
Uni Filter
Airbox 1" drilled holes (3 ontop)
Screen removed
Carb slide drilled
DJ needle with clip on 2nd position
Stock Muffler

 

[DPelletier]

Nice; I had a very similar set up. I used a 142 KH needle on the second clip (no shim under) and a 42 pilot at about 1.5 turns out on the fuel screw.

 

[PeteK]

The stock DK setup has a reputation for running rich. Gas mileage goes down too.

Did you weld a bung into the header pipe to install the O2 sensor?

 

[BeakersWorkshop]

The stock DK setup has a reputation for running rich. Gas mileage goes down too.

Did you weld a bung into the header pipe to install the O2 sensor?

Yep. Circled it in one of the photos. Just behind the heat shield and before the hanger. Will just put a plug in it after I remove the temporary install. Dont even need to take anything off the bike. Just cut some zip ties.

 

[PeteK]

It will be enlightening to see how AFR Changes as you tune the carb. Rather than dropping the needle one notch, I would try a 142.5 main first. It’s overly rich throughout the range above idle, including WOT, and changing the jet will lean it out across that range including WOT, whereas dropping the needle will have more effect in the midranges, but not at WOT. As you noted, 14.5 at idle is good.

 

[Biggs3118]

My new to me bike has been running really rich and I got tired of farting around. I have a 658 with stock exhaust and airbox mods.
Temporarily put a AFR (Lambda/UEGO) gauge onto the bike to see what is going on. So many seat of the pants info and dodgy "info/recommendations" (Bike Specs at the bottom below the images).


Alt: 1050M (3400')
Dyno Jet Kit. C-Clip on 2nd notch of needle.
40 idle Jet, 2 turn out
Keihn 145 Main Jet (the DJ orifices are wayyy too big)

Results:
Idle at 14.5 (nearly Perfect)
Cruising at 12.2 to 13 (Little Rich, Ideally its closer to 15.5ish)
Acceleration 11.5 to 12ish (no change with WOT at full load, Maybe a bit rich).

Next time the Carb is out or I have the tank off I will move the clip to the fist position)

View attachment 35617
View attachment 35618

2008, 65k on the ODO
685 Kit
Uni Filter
Airbox 1" drilled holes (3 ontop)
Screen removed
Carb slide drilled
DJ needle with clip on 2nd position
Stock Muffler

With that setup and elevation you are pretty close. I'd recommend moving the clip to the top notch but try a shim to take up 50% of the distance between the next groove. (Effectively making half sizes)

If you're not experiencing any detonation (pinging) under load I'd say you could lean the main jet out until your in the 12.8-13.2ish range. (Stick with Keihin jets but the dynojet needle is good). Power should improve but it would require also being on a Dyno to calculate RBT vs LBT values. Anyways best wishes.

 

[BeakersWorkshop]

Update.
Changed the main jet down to 142.5.
Needle at second ring (still, did not change)
Idle stayed at 14.5
Accel is now at 12.8 to 13.2
Cruise is 13.5

Considerably more power! Noticeable Torque change for the better and there is power all the way up to 6k when before it was drop off pretty sharply at 5k.

 

[PeteK]

Success!
Your numbers and drivability results indicate it was running too rich. I would still want to see cruise at a higher AFR, say 14 to 15. As a next step try dropping the needle one notch. Your WOT should stay the same, but part throttle should lean out a bit.