Switching to non-vacuum barb manifolds, can I still use vacuum petcock?

ann0yed

XS650 Addict
Messages
191
Reaction score
1
Points
16
Location
Brooklyn, NY
Switching to non-vacuum barb manifolds from JBM (he doesn't drill them for vacuum barbs anymore and I don't feel like drilling my own) can I still use vacuum petcock and switch it over to "prime"? thanks!

-jonathan
 
Well, yes you could but you'll have no reserve because the "Prime" position flows through the reserve tube. When you run out of gas, you will really be out of gas with no back-up. Push the bike a few miles a couple of times and maybe you will feel like installing a vacuum barb, lol. Don't throw your old manifolds away, or at least not until you remove the vacuum barbs for possible installation on the new manifold.
 
Excellent, thanks. I live in the city and am pretty conscious of my tank level so I'm not worried about running out of gas but I do love my CarbMate for synching; I will drill these manifolds out for barbs sooner or later, just want to throw these on and ride today. Thanks 5twins!

-jonathan
 
On the subject of drilling for barbs, JBM says to install the barbs on the carbs instead of the manifolds and I like the idea but I'm wondering about placement. Anyone out there done this? Got a pic?

-j
 
650 carbs from '76 on have threaded vacuum ports blocked off by a set screw. The one on the left carb is obscured by the throttle cable arm but the one on the right carb is more accessible. You may be able to install a threaded barb in place of the set screw and source your vacuum from there.
 
Should be. I ran one petcock only to 1 carb, letting the other carb fill from the crossover line on my 79. OEM cv carbs and oem vacum petcock
 
Well, using the prime or reserve position all the time will allow the very fine silt on the bottom of the tank to get into the carbs. This stuff is so fine it will pass through most filters. It accumulates in the carbs and will eventually cause a problem. If you use a paper filter, the silt will plug it up.
 
Mike's sells a non vacuum petcock to replace the vacuum petcocks. They have an off, on, res.
Leo
 
Back
Top