99 yz250 powervavle part question

What are the small valves on the side for, number 14, and what do they do? Are they worth replacing?

Also, how often do the power valve springs need to be replaced?

power valve side valves.png

Nothing?

You generally don't have to replace anything if its working properly and the parts aren't all carboned up..turn the end of nbr 10 and make sure everything moves properly, middle valve first, outer valves from about halfway.

The side valves open after the middle valve for more top end.

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