GearDriven

Would like to update that I've readjusted the a/f screws with the bike running and it's drastically improved! I did the ol' turn-while-idling-and-wait-for-response method. 3/4 carbs were fine at the factory setting of 2.5-out, but one of them surged up in rpm at around 3.0-3.5-out. It's bizarre how sensitive these things are, but at the same time, turning them all to like 4 or 5-out makes no difference to idle (it's very hard to tell when they're actually turning). As far as I can tell, the rest of the carb system operates correctly. The outcome could have come from two obvious

Thanks for the suggestion. Symptoms are the same with the canister connected & disconnected. There're no liquids inside.

Blocking that port does not allow the engine to rev up at all. That one is the No. 6 Tube in the attached diagrams. To me, it looks like when the intake runner (No. 10 Tube) is pulling vacuum, that allows free-flow between the carbs and the charcoal canister via this No. 6 Tube (Tees into No. 4), and I think it's just open to atmosphere on 40-state bikes.

Thanks all - I forgot to mention that I did replace the foam in that filter with some low density stuff, and also tried running without it attached and had the same symptoms.

Symptoms: The engine speed decreases at a constant throttle position (under no load) - video posted. Under load, the bike pulls hard at WOT, but does not respond for several seconds when the throttle is chopped off and back on again. Massive amounts of exhaust popping on deceleration. The vacuum-operated slides flutter violently at mid-high throttle positions (might be normal?) When converting BACK to CA-spec stock, same symptoms. Story: So this is a CA-spec bike (California not Canada). It ran perfectly OK in its stock form, but I knew it was a littl