Burst images will not upload when sharing to iCloud via iPhoto
If you take photos with burst mode or image stabilization on your iPhone 5s, only the photos you select as favorites when using burst mode and the final composite image shot with image stabilization are added to My Photo Stream. 

If you want all burst-mode photos uploaded to My Photo Stream and your iPhone has iOS 7.1 or later, go to Settings > Photos &amp; Camera and turn on Upload Burst Photos.

Source: iCloud: My Photo Stream overview