Little hats on carbs vacuum ports?

My carbs have little red caps on (what I think are) the vacuum ports.



Are these a common (and ok) modification? The service manual shows vacuum lines coming off each one and connected to each other with "T" connectors.

Carbs 1, 2 and 4 have this. Carb 3 has a hose going to the back side of the petcock.

Thanks,

ZN700LTD

thats normal,but they are usually black.used for hooking up vacuam gauges for tuning motor and carbs. goodluck,happy wrenching!