Has anyone experienced an issue where the kick starter slips when kicking the bike over?

Its usually ok and starts-up after 3-4 kicks when cold but sometimes when I give it a good kick it seems to slip like its missing a cog and jump to the bottom of the stroke.

Cheers for any input?

Reub.
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92 MC21 NSR250SE / 09 ZZR1400
I live more in 5 minutes of riding my motorcycle than some people live in their whole lifetime!