81 XJ650H slow throttle response below 4000rpm

Hey all!

Have been through the forums a few times, burned through the search, and haven't found an answer to this question:

Bike starts well, idles well, and has lots of pickup above say, 4000rpm. If I'm cruising along in gear at speed, gear down, and wind the throttle, the bike leaps like it should as long as I'm above 4000.

However, when I'm below that (such as when I'm starting from a dead stop or accelerating after brkaing), the bike is slow to respond to the throttle. Once I hit about 3.5-4k, the power suddenly kicks in and away she goes.

Doesn't seem to matter if the bike is warm or cold.

Any thoughts on why this would happen?

I'm running a bottle of carb/injector cleaner through the bike as a stopgap measure until I can afford to have the carbs rebuilt and resynched, and am running premium fuel through it to flush out the old low-grade fuel that the PO had in there. Bike hasn't sat for any real length of time that I know of.

Help! She's rideable now, but I have to rev higher than I'd like and slip the clutch longer than I think I should, and I'm worried about excessive clutch wear.

 

Bad gas.
Carbs that are dirty and out of tune.

 

Gotcha. Thanks for the pointer, Nick, will get it in for cleaning asap!