what is vaccum hose for?

[Frost]

i've read that you have to connect a hose on the left carb to the vacuum hole on the frame mounted padcock...

what is it for???...

[Kerry]

Without that vacuum connection, the ON and RES settings on the frame-mounted petcock won't work.  The vacuum pressure exerted through the hose is what moves the diaphragm inside the petcock.

But I thought that on the 2001+ models the hose attached to the right carb.  Is that right?  :dunno:

[Frost]

oh ya...it's the right carb...

so do i connect a hose from the right carb to the padcock??

[Kerry]

Yeah.

Are you saying that you don't already HAVE a vacuum hose between the two?  It's a smaller-diameter hose than the ones that carry fuel.

[Frost]

i have one...but i just wanna make sure...

this is what i have connected now...

the lower T to the fuel oulet on the padcock

2 fuel lines running from tank to the padcock (res and on)

and a vaccum tube from right carb to the padcock

that's it right??
hwo come when i have the tank off and if i plug the vaccum it works...but now that i put everything back together it doesn't???

[Kerry]

Sorry - I got called away.

It sounds like you've got things hooked up right.  When the tank was off, where was the fuel coming from?  Was the tank still hooked up, or were you just running off of the fuel that was still in the disconnected hoses?

You said that when you "plug the vacuum" it works.  On which petcock position?

Also, just to make sure ... with everything put back together does the bike run on the PRI position?

[Frost]

when the tank was off...i put gas in a bottle inplace of the tank...

and by plugging the vacuum...i mean plugging hole on the end of the hose...

haven't tried pri yet...you think that might be the problem??

[Kerry]

haven't tried pri yet...you think that might be the problem??

You don't typically want to run all the time in the PRI position (unless you run out of other options).

I was just wondering if/how it ran in the PRI position, since that position is not dependent on the vacuum hose at all.  It's fine if you run it in PRI with the vacuum hose attached.  If the hose is NOT attached, close off the vacuum port on the carb so extra air won't enter and possibly upset things.

[Frost]

i'll try that...thanks again...