I have a 97 blackbird. Bought it at the end of last summer. It had issues when I bought it and still does. The bike idles fine and will run fine under 60mph and 5k rpm. Above that the engine will pause, stumble, and just sound horrible until I back off the throttle. I can rev it, while not moving the bike, to redline and it seems to run fine, maybe a tiny amount of popping but nothing like what it does going down the road.
I've changed spark plugs. I put a dynojet stage 1 jet kit in it. I have checked the primary and secondary coils with an ohm meter but have not done a spark test. I have tried both the 140 mains and 136 mains that came with the jet kit, raised and lowered the clip on the needle. I even tried a couple of strips of duct tape on the air filter.
The bike runs best with the 140 mains and the needle clip in the 5th position from the top and nothing blocking the air filter. But it still runs horrible.
The bike has a Yoshi rs3 single can exhaust and k&n air filter.
If anyone has any ideas i'd sure like to hear about it. I hate to break down and take it to the honda shop, I know they'll rip me a new one.
Thanks in advance to anyone who is willing to help
David

 

it might be that you need other size needles

 

Since you've done all the carb work, the next thing to check is the ignition timing. Use any old timing light. If it doesn't advance smoothly, replace the spark unit or whatever the blackbird uses. Then pull the spark plugs and check them. Running rich or lean? Probably lean. When you did the carb work, did you clean and check the piston/needle slides for stickyness. One or more of the air bleeds under the vacumn chamber that raise the needle out of the main jets may be clogged. High RPM problems are usually caused by wrong ignition advance or the needle not pulling out of the main jet.