You say it's a 21, but running 18 harness and PGM. What about the flywheel? 18 or 21? The 18 flywheel is slightly less advanced than the 21.
You also don't mention the spec of the bike. If your airbox is stock then 140 mains are probably too big. I just jetted a 21 running slightly batterered Endurance Racing pipes but with stock airbox and 130's were right on the money. I'd already set it up with modified airbox and 142 mains but the guy didn't like the sound (go figure!
) so I put it back to stock.
You might also want to take a look at the condition of your reeds.
Another thing to check, the plumbing from carb to air solenoids has a white plastic 3 way joint that plugs into a filter on the underside of the airbox. If this filter is clogged then the thing will get strangled and will only rev up to about 8K. Seen this many times on airboxes that have been cleaned in soapy water, which then saturates the paper filter inside so it can't breathe. Just unplug the three way joint from this filter and run again to eliminate this.