Vacuum petcocks are toast ... need an alternative...

[CoconutPete]

I have the tank off my 1979 Special. Right side isn't sealing, fuel just pours right out.

If I'm gonna address one side, I may as well address both.

It seems vacuum petcock are just ... a bad idea.

Can I just replace them with the non-vacuum type from MikesXS?

What happens to the vacuum ports on the carbs? Is there some sort of cap?

Is it a straight swap?

I searched, but i didn't find a "beginner's answer".

 

[Stoop22kid]

You should be able to cap off the ports on the carbs I believe.

 

[fredintoon]

Hi Pete,
MikesXS sells a manual gas tap that fits your Special gas tank. They ain't cheap.
Or you can switch to Pingel gas taps and XS650-compatable adapter plates.
Pingel gear is excellent but the price makes MikesXS prices look reasonable.
Later Special tanks only have a single gas tap so you need only buy one tap and a blanking plate.
MikesXS also sells the vacuum spigot blanking caps you'll need.
Or you could link them with the vacuum line you just removed.
What you can't do is just leave them open to let the air in.

 

[650Skull]

Have a look here

 

[Brassneck]

Hey CoconutPete,

I did the exact same thing...my '79 special did great for a year or so with the vacuum petcocks, and then finally failed. I resisted manuals, wanting to stay stock...but finally decided to go manual. I bought two of the ones from mikesxs. I like having the balanced look, but you could do as suggested and just blank off one side and use one petcock only.

I used a vacuum line and connected both ports on the I intake manifolds to each other...works great.

And now, I just keep one petcock closed the whole time, and just turn on the other one to start and ride.

 

[ThatXS650Guy]

Have a look here

Yep. Mine were leaking but then I rebuilt them and they lasted over a year before they started seeping. I took them apart followed the instructions above including flattening the sealing surfaces and they are leak free and work great.
You don't realize how bad the sealing surfaces are until you start refinishing them. I used 400 grit on a piece of glass.
Bought the petcock rebuild kits on eBay for 1/2 of what Mikes charges.
Before:

After:

 

[CoconutPete]

I guess I should have included:

I am not in need of being 100% Authentic on this project.

I am not committed to having 2 petcocks or having vacuum for that matter. Simplicity and reliability are key.

Seems like I can do this:

Remove one petcocok, replace with some sort of cap.
Remove the other petcocok, replace with non-vacuum petcock.
Cap both vacuum ports on the carb off.
Put a splitter in the line and run to each carb.

Do I have this right? So one non-vacuum type petcock (From mikesXS for instance) will do the trick?

This seems like it may be good news...

 

[retiredgentleman]

I guess I should have included:

I am not in need of being 100% Authentic on this project.

I am not committed to having 2 petcocks or having vacuum for that matter. Simplicity and reliability are key.

Seems like I can do this:

Remove one petcocok, replace with some sort of cap.
Remove the other petcocok, replace with non-vacuum petcock.
Cap both vacuum ports on the carb off.
Put a splitter in the line and run to each carb.

Do I have this right? So one non-vacuum type petcock (From mikesXS for instance) will do the trick?

This seems like it may be good news...

Yes, that will work. Actually, you don't even need a splitter line. If your bike has the stock BS38 carbs for 1979, those carbs already have a fuel line that joins the 2 carbs. You can just run one single fuel line to either carb. and that carb will feed fuel across to the other carb. You would have to block the normal fuel inlet to one carb.

 

[weekendrider]

You might be interested in
http://en.650wiki.org/index.php/5.02.1_Vac_Petcock_Conversion

 

[CoconutPete]

Yes, that will work. Actually, you don't even need a splitter line. If your bike has the stock BS38 carbs for 1979, those carbs already have a fuel line that joins the 2 carbs. You can just run one single fuel line to either carb. and that carb will feed fuel across to the other carb. You would have to block the normal fuel inlet to one carb.