1980 BS34 carb tuning for K&N pods

[Zombis]

So this has been quite the project. I have a 1980 650G with BS34's. I live in Redding, CA basically sea level. I am running K&N pods the large oval type and stock exhaust. The carbs have plastic floats and carbs are clean. The butterfly seals have been replaced and currently I have no air leaks. (checked with propane) I finished rebuilding the head and have been riding it for a couple weeks now.

CND needles 3rd slot from the top. (middle)
135 mains
42.5 pilot
2.5 turns out
135 air jet
22 mm float height
notes: Falls on face at WOT

I have a pretty rough stumble at around 4000rpm plugs looked kinda lean. randomly now it will stall. happend on a bridge the other night and almost ran into the back of a prius for the 2nd time (am really getting tired of prius drivers not observing other drivers turn signals and hand signals) spent the next day working on the carbs.

CND needles middle
137.5 mains
42.5 pilot
2 turns out
135 air jet
22mm float
Notes: Can finally go to WOT

Bike pulls alot better after 3500rpms but plugs are black. like smells rich as hell around 33 miles per gallon. so no good.

CND needles lowered one step
137.5 main
45 pilot
2 turns for idle
135 air jet
22 mm float
Notes: WOT no issue Stumbles at 3500. Like stumbles kinda hard below 3500 ocasionally stalls at lights. Still rich?

Synced the carbs, weren't too far off from being dead on.
rough inconsistant idle sometimes its 1500 other times it lopes at 1000

Tore back into the carbs to check the needles had them assembled incorrectly
where the washer was under the E clip spring on top of that.......

Anyone else running K&Ns with the stock exhaust and CND needles? if so what are your jet sizing and needle clip positions?

Ive got the next couple days off to get this solved before i have to back to work and the xs650 is by far more fun to ride than the xl175. My truck has a bad fuel pump so its been 2 wheels for me for a while.
Be it bicycle or motorcycle.

 

[littlebill31]

Have you checked the diaphragms for tears? And did you do the "dead cylinder method" to adjust the mix screw?

 

[CDNTX650]

did you try your stock jetting? i run stock jetting with no stumbles or hesistation. could probably use a very thin shim under the needles though if i could find one thin enough. Stock xs-1 repro exhaust.

 

[5twins]

Do you just have the Canadian needles or do you have the matching Canadian needle jets as well? The 2 are made to be run as a matched set. The Canadian needle won't work correctly in the stock needle jet.

 

[Zombis]

carb diaphragms rise and fall when you blow into them and they looked good when i moved the clip position to lower the needle.

5twins I do have the matching Canadian needle jets. I also found a picture that you posted and thank you.
http://www.xs650.com/forum/showthread.php?t=6302&highlight=needle+assembly
This exploded diagram made me rethink how i have always taken apart and reassembled the carbs. the washer that goes above the E clip was under the clip, being used as a shim. If I would of realized it before i might not have been in this mess. but o well learned something new about these carbs today and im very happy about that i found it before I started running in more circles.

Took it for a spin this afternoon after correctly putting the needles together properly. ran better than it ever has put it into third whle i was cruising and let the rpms fall pretty low and then grabbed a handful of throttle. pulled really well. going to take it out tomorrow again and see how it does.

 

[littlebill31]

Glad to hear it's running better.
To check the diaphragms you need raise the slide up into the top of the carb and hold it there, then (using your thumb) cover the top port (the oblong one) on the air filter side of the carb body, now let the slide go. It should either not move or go down really slowly. If it just drops there could be a bad seal around the top or it could be torn.

 

[Zombis]

137.5 main
45 pilot
second clip position from the top
2.25 turns out
switched from Autolite 63 to NGK BPR7EIX
Notes: Runs well has slight over rich stumble at higher RPMS at WOT. MPG 35-38.

This is turning into the quest the highest fuel economy possible. I would like to get at least into the upper 40s. I do understand that may be tough with the stock gearing. Going to try a 135 main in it today and play with the mixture a bit and do another sync.

 

[XSLeo]

The BS34's try 3 to 3 1/4 turns out on the mix scews. Adjust for best idle from there.
I agree with CDNTX650 Start with the stock jets. The K&N filters work ok, they flow a bit more air than stock if you have a more open exhaust.
With your stock exhaust maybe one up on the pilots and mains will probably be enough.
Every time you change the pilots, set the mix to the 3 to 3 1/4 and adjust from there.
From some of the reading I have done the K&N's even the large ovals don't work as well as they should on a CV carb. An off idle stumble most often.
The round 4 inch long Uni-filters work better. No off idle stumble. They helped mine run better.
Leo

 

[CDNTX650]

like i said, i run pods with stock exhaust and all i am doing is trying a 135 main. The bike runs pretty good as is on stock bs34 jetting, but could probably use a bit more. So the 135 is easy to try.

 

[Zombis]

I dropped back down to the 135 yesterday and am almost done fine tuning the mixture 3 turns out was a pretty good starting point. thank you xsleo. going to toy around with it for a little longer today and take it out for a ride and see how she does. The Trick R Treaters started coming around yesterday so I had to stop what I was doing to hand out candy.