Two petcock tanks vs. single

[aldo5468]

Is there any benefit to having a vacuum style petcock? How do I modify it?

There is a safety aspect to vacuum petcocks - gas flow to the carbs is stopped when the engine stops.

 

[Brassneck]

Or you could do what I do...I have TWO non-vacuum petcocks, and simply use one side only...the other is left off, and if I run low, simply turn the other on. Simple.

Oh...wait, does the '81 tank only have space for one petcock? If so, never mind.

 

[CoconutPete]

My 79' had 2 petcocks when I bought it. I now have a tank on there from an 81' I think - not really sure when it's from.

I run 1 manual petcock (from Mike's) on that setup and the fuel line splits right before the carbs and go to both. No issues, just did a police-escorted toys-for-tots style ride clear across the city of Charlotte a few weeks ago.

I still have the old tank as a spare. Since i have changed my vacuum intake manifolds for non-vacuum ones, I have a different setup on that tank. One side is blocked off with a beautiful creation I have made out of an old vacuum petcock, a grinding wheel and some JB weld. It doesn't look half bad actually. The other side has the old vacuum petcock but with the vacuum port capped off and the in-tank filter removed. I just use it on "prime" when I run that tank which doesn't happen often. This is when I live dangerously because there is truly no reserve there. I did run out of gas when I first bought the bike and tried this trick and tipping the bike got me nothing - maybe I wasn't tipping far enough.

 

[weekendrider]

Did you throw the rest of the petcock away? If not you may want to try this.
http://en.650wiki.org/index.php/5.02.1_Vac_Petcock_Conversion