CDI box confusion on my rebuild

[The Shallow]

I'm putting together a stripped-down project bike but I'm stuck regarding the CDI. The original had a vacuum port, but I picked up an aftermarket unit that supposedly doesn't need it. The problem is, the wiring was a mess when I got the bike, and I can't find a clear diagram that matches this new CDI. Do I actually need that vacuum-style CDI to get it to fire, or has anyone had luck running one of the aftermarket ones without it?

 

[ManFromAnotherWorld]

An aftermarket CDI without the vacuum port can function, though engine response at part throttle may be different. Finding a correct wiring diagram for your specific setup is the real challenge. What year and model of Vulcan are you working on?

 

[Confident-Value-27]

Yeah, from what I know, some aftermarket CDIs don't need the vacuum port, they use fixed timing or digital curves instead. But wiring can be tricky since not all units follow the same pin layout. Do you know if your new CDI is AC or DC type? bec affects how it connects.

 

[rave_jude]

Vacuum-style CDIs are often overhyped relics; unless you're chasing factory-original restoration points, ditching them for a decent aftermarket unit is smarter, cheaper, and won't magically ruin your bike's performance despite purist fearmongering.

 

[The Shallow]

@rave_jude That's reassuring to hear. I just want it running reliably without chasing vintage specs, so sounds like sticking with the aftermarket CDI is the way to go.