Kz400b carb balancing

Went to balance the carbs on the kz400 and immediately guages reading late valve timing is this normal for these type of carbs .

What is "late valve timing", and why/how is a vacuum gauge providing this information while syncing?  

And needless to say, the valve clearances and carb function needs to be otherwise correct before performing a sync.  Sync is the last step in the process.

Hi 
its just the red section on these gauges that indicates late valve timing just wondering if anyone has used these gauges and had the same result.

Nessism wrote:

What is "late valve timing", and why/how is a vacuum gauge providing this information while syncing?  

And needless to say, the valve clearances and carb function needs to be otherwise correct before performing a sync.  Sync is the last step in the process.

It looks like it is listing multiple possible reasons for a low vacum reading (but not all of them)?