@Lewis > Could you please explain a bit better what you meant by the bpm changes on Rekordbox?

If you are using CD's in the CDJ's, or un-analyzed files on a flash drive in the CDJ's, then sometimes the tempo can vary throughout the track as it tries to calculate it within the unit itself and isn't always 100% accurate. For the best accuracy, you should only use the BPM count as a guide and use your ears for beat matching. ;) 

Well, I play a track within Rekordbox and watch the BPM continually changing whilst playing, the same on the CDJ, I use MP3's with tunes from Rekordbox, and when I'm in the mix the BPM Keeps changing on the track thats playing

@Lewis > Have you correctly imported and analyzed your tracks?
In the preferences, did you analyze the tracks in "Normal" or "Dynamic" mode?

You should use the the "Normal" mode for digitally produced EDM tracks that should follow a constant beat. You should use "Dynamic" mode for live instrument tracks where a drummer may be slightly off beat therefore can result in a fluctuating tempo.

However, there have been users who find digitally produced tracks with slightly off beats. In this case, I would recommend using the drop down arrow to the right of the waveform in Rekordbox, and manually make sure the grid is lined up exactly with your track. If you've done this correctly, the tempo on Rekordbox should not fluctuate throughout a track, nor on a CDJ.

As long as you use Rekordbox analyzed files on the CDJ's, they should provide a constant BPM on the display.

Could you please double check the analyze mode, and ensure your tracks have analyzed properly, the grid is lined up throughout the entire track, and you've exported the files properly if you're using a USB device or SD card.

If you are still having troubles, please reply here with the results and a bit more information on what exactly you did. :)

@ Foster

Problem sorted thanks very much, i have analysed the tracks in normal now and the bpm stays the same, im new to cdj's having been a vinyl dj for years.

Still getting to grips with Rekordbox/CDJ's

Cheers.

@Lewis > Glad you got it and thanks for the update. :)