Petcocks

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1911master

1911master
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I am sure this has been answered, but I am a newbie so forgive me.

I have a 1979 650 that I am getting ready to fire up. The tank is clean and painted, I am installing new non-vacuum Petcocks, since this is a twin petcock bike.

I know I need to plug the vacuum outlet so my question is when I fire this up do I place the petcocks open or reserve.

I also know to shut off all fuel when not running. Thanks
 
You should set it to open, and then when the gas level drops to the point where no gas is getting to the carbs switch to reserve, depending on what type of mpg you're getting, you might have 25 -40 more miles before you run out of gas.
 
Yeah, don't forget about your reserve. Vacuum or not. I spent hours rebuilding carbs and getting the bike running well and finding myself freaking out when all of a sudden my bike started running like crap, hardly at all.. I panicked.. but then realized it was just running out of gas..switched to "reserve" and all was fine with a trip to gas station. Lol
 
hmusket said:
you might have 25 -40 more miles before you run out of gas.
Click to expand...

I've read of people getting less with the replacement petcock. If it was me, the first time I hit reserve when it was convenient I'd run all the gas out into something and see how much was there.
 
Ok another question, I looked at the Petcocks and they have the funcky screen filter that goes in the tank and the screen at the on off valve. Should I discard these and just run and in line?
 
I have tried both ways on the many bikes I've built,in-line filters are nice that you can see when they get dirty but I think they are more restrickive.The screen with the pet-cocks only stops large particals and for the most part I only empty the tank remove and clean the pet-cock screens during winter.After you use reserve the first time check the millage,I use my trip meter as a fuel gauge=120 miles about 2 gallons.
 
Vacuum petcocks require a vacuum to operate. There is a diaphragm valve inside that requires suction to open it. Two solutions, acquire vacuum barb intake manifolds for the motor or make this modification.
 

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