hi ive got a blackbird carb ,dyno jetted ,k&n ,and micron road legal cans it goes realy well but surges when cruising could it be carb balance or maybe float levels .
Hiya Doug, It could be sticking float or needle. Also it could be when bike warmed up you have a hole in one of the carb diaphragms or leak in one of your intake joints between carb and engine. Not had this problem on my blackbird but something similar on a GPZ900 turned out to be intake joint leak.
Read the notes on the dyno jet instructions about surging. It should tell you how to stop it. you can set dyno jet your self but it is time consuming. the best way is to put it on a dynometer. Its not cheap but they should get it to carburate spot on.
This is most likely down to running a weak mixture-definately check your dynojet settings,pay particular attention to the carb float heights-if they are a bit low,i.e.the float height reads higher than recommended,your fuel level will be low & it`ll be harder for the jets to suck it up leading to surging usually around cruising speeds or constant light/trailing throttle. The float height is usually measured with the carb at 90 degrees so that the float hangs down,pivot pin to top,just resting on the float valve without putting pressure on the spring loaded pin on the valve-measurement is then taken from the gasket face to the furthest edge of the floats.
![blackbird surgeing - Forums [Biker Match]](/images/backgrounds/strips/8mobileLQ.jpg)
![blackbird surgeing - Forums [Biker Match]](/images/backgrounds/strips/8desktopLQ.jpg)
