Hanging throttle

05 xrr 650 uncorked. Without any new adjustments throttle seems "hang" a little this is a new issue that just appeared. No apparent mechanical hangups in throttle cable, but when reducing the throttle quickly engine rpm decrease seems to lag by a second or two. Throttle adjustments haven't helped.


Jetting and valve adjustment are my thoughts.

These engines have a considerable amount of intake vacuum when the throttle is chopped from speed. This can cause excessive friction between the slide and the slide bore which results in the slide returning to idle position more slowly than normal. This might be your problem.

Is there a solution? I was considering venting the air box anyway to provide more air - would that help?

Has the weather changed recently? I ask because you said this was a new issue. In my experience, a hanging idle is most often caused by a lean pilot circuit. What pilot jet are you running? Does adjusting the fuel screw affect the behavior of the idle? Might be worth cleaning the carb (remove and clean all passages with carb cleaner and compressed air) to eliminate that as the source of the problem.

I would play with your pilot adjustment. I've noticed the same issue, but it was a rich pilot condition for mine. I say clean the carb, and fiddle with the jetting a bit.

What is your setup? i.e main jet, pilot jet, needle jet position, any HRC parts, cutout side panel, etc.

Decrease your idle speed. This is pretty common. If your bike doesn't idle well after the idle speed is reduced, then adjust your pilot screw (fuel screw) to achieve the highest idle.

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