Running lean? Why?

So after a rebuild on my 2005 YZ125 it appears to be running lean... The bike will not start first kick like it used to, It starts a lot easier with the choke on, and the idle seems faster to me, any idea why?

Bad left side crank seal.

Bad reed block

Thanks for the reply! But I didn't touch any of that during the rebuild... Before the rebuild it ran perfectly, would that really be an issue to consider?

All can fail at any point. If you did not touch any of them, what did you 'rebuild'?

Sorry I guess I could have been more specific.... I did a top end rebuild only replacing piston, ring and wrist pin. Replacing the old cast piston with a new forged one should matter should it? I did clean the carb, however I'm reluctant to mess with any of the settings because of how perfectly it ran before.

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