vacuum lines

[jetmechmarty]

My existing petcocks are pretty trashed i'm going to get a new set of non vacuum petcocks from mike's XS I heard that they fit even though they are designed for 650s

http://www.mikesxs.net/products-34.html#products

What XS1100 do you have? XS650 taps will mount only to a standard tank.

Why not do this instead?
Rebuilding Yamaha Vacuum Operated Fuel Valves (Petcocks.)

[1980cm400t]

I have a 1980 xs1100sg It is a basket case that i got for free I am doing a complete rebuild on it. I replaced the stock tank with a standard which is bigger and i like the style better. In the pile of loose parts i have an octy and vacuum petcocks that are completely seized up. I am looking to simplify the system and gravity feed the fuel to the carbs. I'm not sure how the original fuel system was set up as when I got the bike it was mostly disassembled and there were extra fuel system components.

[jetmechmarty]

I have a 1980 xs1100sg It is a basket case that i got for free I am doing a complete rebuild on it. I replaced the stock tank with a standard which is bigger and i like the style better. In the pile of loose parts i have an octy and vacuum petcocks that are completely seized up. I am looking to simplify the system and gravity feed the fuel to the carbs. I'm not sure how the original fuel system was set up as when I got the bike it was mostly disassembled and there were extra fuel system components.

Switching to the standard tank has you with two fuel systems. You should remove the vacuum shutoff (octy) that is mounted on the carbs. Put it away as you don't need or want it in the system with the standard tank. Your least expensive solution is to rebuild the petcocks on the standard tank. Replacing them will cost twice as much. You'll need vacuum to both of them. Plumb it as a standard.

Most likely, you can salvage your petcocks as per this link:
http://xjbikes.com/Forums/viewtopic/t=25058.html

[natemoen]

The is also the option of modifying the standard vacuum petcocks to be completely manual and disable the vacuum portion. Don't know where the thread is though.

[1980cm400t]

Unfortunately I don't currently have any petcocks that are in serviceable condition so I figure I might as well start fresh with a new set. If i'm going to spend the money i'm going to spend it on all manual petcocks and not have to deal with the octy or vacuum actuated petcock valves.

[natemoen]

Unfortunately I don't currently have any petcocks that are in serviceable condition so I figure I might as well start fresh with a new set. If i'm going to spend the money i'm going to spend it on all manual petcocks and not have to deal with the octy or vacuum actuated petcock valves.

As has been stated, you are going to spend a lot more money getting new petcocks (that are not quite right anyways) than you would if you just fixed the ones you have and then you could just eliminate the vac function.