(unpredictable) Flat spots off idle (78 special stock carbs)

[cmattina1]

I've been reading through the carb guide and am considering experimenting with the needle and jet changes.

However, though i understand that reading the bikes performance at certain RPMS is telling of where the issues lie, i.e. i have a flat spot around 5rpm that is almost always there. I don't see how flat spots off idle, that only occurr every once in a while (1 in 10-15 stop signs or lights) fit in.

Any suggestions?

 

[5twins]

That could be float level related. If your fuel levels in the bowls are a bit low, it might act that way. The fuel sloshes forward and back in the bowl when you stop or take off. Depending on how much it sloshes around, it may give a momentary fuel starvation problem sometimes if the level is low to begin with. The spec for your carbs is 24mm +/- 1mm. I have a '78 as well and experimented with both extremes of the spec (23 and 25mm). My bike ran best @ 24mm.