When I change my petcocok to manual do I plug the vent?

[SpidyJ]

Wonderin......don't see any posts specific to the vent.

thx
any help
jpw

[old2soon]

Our fuel from the stock tank is gravity feed so NO don't plug the vent. RIDE SAFE.

[Bone]

Mine has been manual since 2010.

Here's a link with pictures and instructions I followed.

http://daughertymotorsports.com/howto/tankvalve/tankvalve.html

[Patrick]

I'm wondering if we have a terminology problem. What do you mean by vent ? If you mean the gas tank vent at the bottom rear of the tank then no it is not to be plugged as it still needs to remain open and clear. So, when replacing the tank make sure the line doesn't get kinked [ common problem].

[SpidyJ]

The vent on the petcock itself, not the vacuum line....the vent hole.

I removed the plastic disc and the little piston but left spring and both diaphragms full size.  Filled the vacuum port with a small selfltapper and some loctite.
Seems to work fine dry, just don't want a fuel leak once I install it on the tank out of the vent hole.

Thx
jpw

[Bone]

From the link I posted;
In this picture you can also see a that a small section of the old vacuum hose has been used to connect both the old vacuum port and the vent port.  This is necessary because the diaphragms no longer isolate the fuel.  You can also use JB Weld to seal the holes.

[SpidyJ]

So the answer is yes.......seal both the vacuum port and the vent hole.

Thanks!

[Bone]

Yes they used the hose attached to both and said "or you can seal them shut with JB Weld".

I've logged over 100k miles with the setup.

[Patrick]

I guess I had the terminology issue. I thought you were changing/replaccing the petcock.

[Wewaman]

Patrick as far as the hose off the bottom rear of tank, is it a vent hose?  that hose has a clamp on the far end.  is that supposed to just hang free if so then why the clamp ?  And as far as the petcock it has 3 ports--  1 fuel -  1 hose that goes to #6  intake runner,  and a little short port .  Please enlighten me as to what these should look like. 
Thanks Tony

[Patrick]

The line from the rear of the fuel tank is a vent which needs to be clear/free. There should not be a 'clamp' on that line, but, there should be an open ' T ' slightly above the end of that line. That ' T ' is a vacuum break and one 'nipple' has nothing attached, suppose to be that way. Its quite common to kink this line when reinstalling the fuel tank, and, if it happens you'll know it soon enough as the engine will quit running or start stumbling from fuel starvation.

Another line also near the bottom of the swing arm is a drain line that should have an end plug with a 'clamp'. That line goes to the breather box and should be drained every now and again. What comes from that line is affectionately referred to as 'dragon drool'.

I can't speak to the original petcock without looking at one. Its been so long since I've had any doings with one that I don't trust my memory about its workings. I don't want to give any bad or wrong info.

[Wewaman]

thanks Patrick 
I will look into this when I get home this evening.
Tony

[Gryphon Rider]

If you made it manual by cutting out the centres of the diaphragms, then, yes, you need to plug the little vent hole on the bottom of the valve.  If you did it by leaving the small diaphragm intact and merely put the spring on the other side of it to hold it open, then there is no need to plug that vent as it is separated from fuel by the small diaphragm.

[Ricky-D]

Probably one of the smartest investments you can make is a new aftermarket gas petcock.

Modifying an oem petcock is Ok, but they are inherently a poor performer as an "off"/"on" petcock

due the fact there is no positive feedback from the stocker that the gas is actually shut off.

And turning it to "off" and riding to see and observe a "stutter" is not an indication it is

completely "shut off".  It doesn't take but a drop or two per minute of gasoline

to do it's damage. Naturally other conditions apply.

***

[SpidyJ]

You do know that now instead of two valves shuting gas off you now have only one,if it was leaking you would have saw gas driping out of that vent you were talking about.  Good luck

I haven't installed the manual one yet, I'm converting a spare I bought.
Also, I do have a Dan Marc in-line.