vacuum petcocks

[wheelsrus]

i have recently picked up a '78 with vacuum petcocks. i tried to read other info on them , not sure what the problem is with these. even after being rebuilt are they still not reliable? is the problem that somehow gas can still flood the carb? I have a 75&74 with regular ones should i just use that type? Thanks

 

[650Skull]

Some light reading

https://www.xs650.com/threads/rebuilding-yamaha-vacuum-operated-fuel-valves-petcocks.20662/

https://www.xs650.com/threads/vacuum-petcock-on-off.50190/

 

[5twins]

I've been running the original vacuum petcocks on my '78 since I started running it back in 2005. They've worked fine. One did spring a leak, not from any of the rubber sealing bits but rather from one of the cross-drillings they plugged and epoxied. I fixed it with JBWeld.