Vacuum caps

[cogsman]

Hi All,

I bought one of BonS DigiSyncs a while back, and I am getting ready to sync my carbs.

I don't really understand the purpose of the vacuum caps that are on the nipples to which I am supposed to connect the hoses.

I'd appreciate some help in understanding what these things do. I'm also wondering why some of the caps don't go anywhere, while others have hoses (specifically cyls 3 and 6). I notice that Cyl 3 is connected with a different type of hose, and I notice that Cyl 6 goes to the petcock.

BonS provides 6 vacuum caps of his own design in the package; this isn't about the DigiSync, it's about whether you can really disconnect all hoses and just replace with those caps... can you?

What is all this about? I'm asking because I don't want to disconnect anything i'm not supposed to, and more importantly I want to reconnect everything properly after carb syncing.

[Steve K (IA)]

The vacuum caps sent would be to use to replace the ones currently on the bike.  If yours are original, they need replacing and the ones that came with the DigiSync are better quality.  

Yes the hose to # 6 goes to the petcock.  When doing the sync, you need to draw a vacuum on the petcock so gas will flow.  This hose will need to be pinched off to hold the vacuum to the petcock.

The 2 hoses connected to the center intake runners on each side are joined at a "T" and then go to a valve under the tank.

You just need to remove the 3 vac hoses and 3 vac caps and hook up all 6 hoses Bon sent and connect those to the DigiSync.

When done reconnect the 3 vac hoses and cap the remaining vac nipples with the caps Bon sent.

[The emperor has no clothes]

Ditto to what Steve said. I would add that I watched Bon do a couple synch's at Inzane without pinching off #6. There is enough gas in the bowls to do a synch. And if it takes you longer you can just hook up #6 again when it starts to sputter. I had no problem doing the synch before it ran low.

[cogsman]

This is very helpful, thank you!

So to pinch the hose on number 6, do i pinch it (I have a hemo i can use) and then remove it from the cap?

And should the engine be running before I remove it?

[The emperor has no clothes]

This is very helpful, thank you!

So to pinch the hose on number 6, do i pinch it (I have a hemo i can use) and then remove it from the cap?

And should the engine be running before I remove it?

That would probably be the easiest way. I think some guys remove it and just suck on the hose to create a vacuum also. I  would your bike warmed up and have the carb linkage removed beforehand. I think Bon has a video on his site of doing it if you haven't seen it yet.

[cogsman]

Yes I saw his vid but I don't recall it making any mention of pinching off the hose. In any case, it sounds simple enough, and I really appreciate all the feedback!

Will give it a try as suggested.