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-   -   Replaced petcock still have gas in vent tube (https://www.vn750.com/forum/22-carbs-fuel-system/94746-replaced-petcock-still-have-gas-vent-tube.html)

dad220 06-09-2017 07:08 PM

Replaced petcock still have gas in vent tube
 
I just purchased a 2003 Vulcan 750. Ran it a few days then gas started dripping from the petcock as one of the fittings was loose. My neighbor who is a master auto mechanic and has several bikes himself told me it was definitely the petcock. Replaced it with a new one from Kawasaki, rode it to work, and it is dripping from the vent hose that goes to right side. I do have a little pop when I let off the throttle from the same side and was wondering if that cylinder is running to rich, does it return the excess gas to the petcock via the line? I have spent every last dime I having buying the bike, correct riding gear, and now the petcock and do not know what it may be other than the carb running rich.

Any help would be appreciated!

ubertalldude 06-09-2017 09:11 PM

Are you talking about the vacuum line coming from the left-hand side of the bike? That is the one that goes from the low part of the front cylinder's carburetor into the bottom of the petcock.

OR are you talking about the vacuum line from the right-hand side of the bike that goes around the engine and underneath the seat/behind the side cover?

The left-hand side vacuum line activates the petcock, the right-hand side vacuum line is for an emission system which can be removed. Look up marbling/coastering/coasterizing on this forum.

Neither tube should leak, unless the petcock is leaking through the vacuum port on the LHS, as both tubes are hooked to a vacuum port, unless you do have your idle mixture screws set really rich.

Could you take a picture of the leak? That would help us pinpoint it better

OleDirtyDoc 06-09-2017 09:36 PM

also how about an introduction in the newbie section so we can get to know you a little?

Sent from my LGL34C using Tapatalk

dad220 06-10-2017 09:31 AM

It is the right side vent on the petcock that goes to the right side carb. Hard to really get a clear pic. This is a brand new petcock. Not sure if the popping sound when I let of the gas at higher RPM's is associated with it, but I have a feeling it is an excess fuel problem. Bike runs very strong and has no idle nor high RPM issues other rhan this.

Thanks,

David

Spockster 06-10-2017 10:12 AM

Quote:

Originally Posted by dad220 (Post 1189162)
It is the right side vent on the petcock that goes to the right side carb. Hard to really get a clear pic. This is a brand new petcock. Not sure if the popping sound when I let of the gas at higher RPM's is associated with it, but I have a feeling it is an excess fuel problem. Bike runs very strong and has no idle nor high RPM issues other rhan this.

Thanks,

David

That doesn't sound right, but it's real hard to see where all the lines run. Normally, the center port of the petcock (vacuum port) runs to the left carb. Then each side port (fuel) runs to each carb fuel inlet.

In stock form, a vent hose comes off each carb, into a tee, then a single vent line runs to the right side air filter box.

Then as described, the right carb has a vacuum line that runs to the emissions valve under the seat.

Left/right is identified as you are sitting on the bike, versus standing in front.

Now, it is possible to connect the petcock vacuum to the right side carb, it would make no difference, except a lot longer hoses would be needed.

Can you describe again where the fuel is coming from? If it's the right hand port of the petcock as you look at it from the side of the bike, that is a fuel port and may be loose and leaking as your old one was. Not sure right now.

The pop on decel is more than likely from a lean condition at idle. There are "coast enrichers" on the carbs that can stick, and the emissions system can play a part in causing decel pop also. Removing emissions and adjusting air screws can help. See: "coasters" on the site, also called "coastering", I think.. Mine still popped after coasters were done, but a few rides with seafoam and popping stopped (stuck coast enrichers).

ubertalldude 06-10-2017 11:36 AM

Sounds like the fuel line from the "right" side of the petcock (towards the rear of the bike) is leaking, which would be no fault of the petcock, but likely a loose/old fuel line.

You could probably get away with putting a small hose clamp on there to see if it stops the leaking, or replace the fuel line.

Spockster 06-10-2017 11:39 AM

Quote:

Originally Posted by ubertalldude (Post 1189202)
Sounds like the fuel line from the "right" side of the petcock (towards the rear of the bike) is leaking, which would be no fault of the petcock, but likely a loose/old fuel line.

You could probably get away with putting a small hose clamp on there to see if it stops the leaking, or replace the fuel line.

Could be, but those fittings are only a press-fit and will turn if you twist them.

Knifemaker 06-10-2017 12:43 PM

If the fitting was loose, you could have just tapped it in rather than buy a new petcock....but I'm not clear where it's leaking either...


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