New petcock having issues

[dta]

I wasn't able to see if anyone has had this happen in the search so I though I'd ask for a little help. I have a brand new petcock, in a fresh POR-15 treated tank ,with fresh gas... Check

Now the bike runs perfect on prime, when I turn it to on gas just trickles out. It's almost like the vacuum is weak from the carb. Eventually It will just starve itself of gas.

Carbs are completely cleaned and rebuilt no complaints. My only though is that the petcock wasn't assembled correctly. Also that the hose was clogged but I already checked that. Also made sure I had the vacuum diaphragm o-ring installed on carb #4.

So my question would be has this happened to anyone before? Or any ideas I'm overlooking?

[Kreylyn]

I wasn't able to see if anyone has had this happen in the search so I though I'd ask for a little help. I have a brand new petcock, in a fresh POR-15 treated tank ,with fresh gas... Check

Now the bike runs perfect on prime, when I turn it to on gas just trickles out. It's almost like the vacuum is weak from the carb. Eventually It will just starve itself of gas.

Carbs are completely cleaned and rebuilt no complaints. My only though is that the petcock wasn't assembled correctly. Also that the hose was clogged but I already checked that. Also made sure I had the vacuum diaphragm o-ring installed on carb #4.

So my question would be has this happened to anyone before? Or any ideas I'm overlooking?

First step is to rule out the vacuum from the engine as an issue or if it's the petcock.

Pull the fuel line and put another line on the petcock that runs into a catch container. Pull the vacuum line off the carb, and then apply suction on the hose. Fold a kink into the vacuum line (to keep that vacuum pressure) and you should see fuel flowing and keep flowing full volume for at least 1 min.

If it's not flowing properly ever, definately an issue inside. If it flows fine only when your applying suction but won't keep flowing after you kink the line... you have a leak somewhere. Either the vacuum line or the petcock diaphram.

Krey

[remykimes]

listen to kreylyn... hes a katana jedi

[Wild-Bill]

listen to kreylyn... hes a katana jedi

AND he's got good advice...

My one exception to Krey's post would be the idea that a decreasing flow with the vacuum line pinched could just as easily be because you don't have enough of a seal in the pinched line. The whole human factor thing, you know...

[dta]

Krey does. Hes helped me a ton of times while searching for stuff.

Did what you said, also have another brand new line I threw on just for giggles. Still doing it so looks like it's the diaphragm. Thanks guys

[Kreylyn]

Krey does. Hes helped me a ton of times while searching for stuff.

Did what you said, also have another brand new line I threw on just for giggles. Still doing it so looks like it's the diaphragm. Thanks guys

If you open up things in there, done rule out other possible issues. Wrong/incorrectly sitting spring behind the diaphram, improperly installed selector internal on the other side, etc... but a hole in the diaphram would definately cause a similiar issue.

Krey

[Riffraph802]

I have a 1994 gsx750f
Just bought a new battery
Got it started but it's not idling
I primed the gas lines and then put the tank back on
It started but was @ like 5k rpm ?
Then it died the petcock won't feed it gas

[Kreylyn]

I have a 1994 gsx750f
Just bought a new battery
Got it started but it's not idling
I primed the gas lines and then put the tank back on
It started but was @ like 5k rpm ?
Then it died the petcock won't feed it gas

Did you have the vacuum line on the petcock with the other end properly connected to the carbs?

If yes, then clean/repair/rebuild your petcock.

Krey

[listoa69]

i am having the same problem that DTA is but I am unable to follow kreylyn's instructions can someone dumb this down a little for me please. Thank you.

[Kreylyn]

i am having the same problem that DTA is but I am unable to follow kreylyn's instructions can someone dumb this down a little for me please. Thank you.

If you remove the gas tank from the bike, it might be easier to see and understand. If you have the tank removed, then here is some info to read up on how things work...

The petcock info... http://katriders.com/wiki/index.php5?title=Petcock

Rebuild the Petcock... http://katriders.com/vb/showthread.php?t=96553

Hose connections... http://katriders.com/wiki/index.php5...se_Connections


Read all that... and you should have a clear understanding of how things work, and make sense of the instructions at that point.

Krey