Persistent flat spot at idle?

[patanga]

Can anyone offer some suggestions as to what might be a cause of a persistent flat spot symptom that my 1995 R100 is experiencing. Both Bings have had kits through them and I have the idle set at approx 1100 RPM on the BMW tacho to keep it above the low oil pressure warning light. It usually occurs when sitting at the lights and I throttle on to take off and it flat spots and snuffs??

[George Ryals]

A clogged or restricted idle air or idle fuel passage in the carb body. You can identify which carb is the problem by lifting the throttle cable at each carb(one at the time). Probably only one will have the flat spot.

[SteveD]

Are the holes in the idle circuit blocked?

Is the idle mixture screw blocked?

edit: beat me to it George! At least we had the same idea!

[Kurt in S.A.]

Carbs resynched? Typically, the carbs are sensitive to just off idle differences in vacuum. That's why you synch the carbs at 1500-2000 RPM and then confirm at higher RPMs.

Kurt in S.A.

[sterob]

Did you have the butterflys off to change the shaft o-rings?

[Jean]

On "older" Bings, there is an intermediate port between the idle-port and running on the main jet. I'll vote for IT being obstructed, Count me #3 for this.
I've had problems like this before...gum-goopy stuff from "modern" gasoline!! I use a fine COPPER wire (unwound from a stranded wire!) to clean these sixe ports. A STRAND from some old lamp cord might be fine enough.
Be sure this port is clean before trying to sync.