Petcock vacuum hose questions

arvindb · August 30th, 2022, 03:28 PM

Recently purchased a 2012 Ninja 250, took the farings off for the first time, and noticed that the petcock had been set to prime by the PO.
The vacuum line is not connected to the petcock either. There's a tube coming off the carb that's just hanging loose (what I presume to be the vacuum hose?)

I looked up some pics online it would appear that the vacuum hose is typically connected directly from the carb to the petcock, this is not the case on my bike. There's a T coming off the line and one end seems to be going into something underneath the gas tank at the front of the bike.

Should I just hook up the hose, set the petcock to on, and see what happens? Is there any risk to doing so? Zero experience working on bikes before, so forgive me if I'm way off base with any of this. Pic below for context, the hose on the right side of the T connector is disconnected.

DannoXYZ · August 30th, 2022, 09:15 PM

Yes, vacuum line goes to carb. You must have CA model with T on vacuum line

As test, with petcock switched to ON:

- apply vacuum to small vacuum hose, should flow fuel
- remove vacuum, flow should stop completely.

If it leaks, should rebuild petcock

arvindb · August 31st, 2022, 12:09 AM

I don't believe T fitting on my bike is where the CA emissions fitting would be. The connection is on the vacuum hose labeled "vacuum hose to petcock". The hose labeled "Coasting enricher vacuum hose" appears to be directly connected from one end of the carb to the other, no T.

Or am I misunderstanding the attached pic?

DannoXYZ · August 31st, 2022, 01:27 PM

No you got it. Functionally same:

1. TWO vacuum ports, one on each carb
2. one port goes to petcock
3. one port goes to coast-enricher
4. one has T for CA emissions under tank

You can put T on any vacuum hose. It's better to have configuration above with dedicated hose just to petcock alone. That ensures most vacuum for petcock without any interference from other devices sharing vaccum hose. If you end up with vacuum leak from cracked hoses or plastic nipples, it'll only affect coast-enricher and not cut off your fuel-petcock as well.

August 30th, 2022, 03:28 PM	#1
arvindb ninjette.org newbie Name: Arvind Location: Austin Join Date: Aug 2022 Motorcycle(s): 2012 Ninja 250 Posts: 7	Petcock vacuum hose questions Recently purchased a 2012 Ninja 250, took the farings off for the first time, and noticed that the petcock had been set to prime by the PO. The vacuum line is not connected to the petcock either. There's a tube coming off the carb that's just hanging loose (what I presume to be the vacuum hose?) I looked up some pics online it would appear that the vacuum hose is typically connected directly from the carb to the petcock, this is not the case on my bike. There's a T coming off the line and one end seems to be going into something underneath the gas tank at the front of the bike. Should I just hook up the hose, set the petcock to on, and see what happens? Is there any risk to doing so? Zero experience working on bikes before, so forgive me if I'm way off base with any of this. Pic below for context, the hose on the right side of the T connector is disconnected.

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August 30th, 2022, 09:15 PM	#2
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	Yes, vacuum line goes to carb. You must have CA model with T on vacuum line As test, with petcock switched to ON: - apply vacuum to small vacuum hose, should flow fuel - remove vacuum, flow should stop completely. If it leaks, should rebuild petcock

August 31st, 2022, 12:09 AM	#3
arvindb ninjette.org newbie Name: Arvind Location: Austin Join Date: Aug 2022 Motorcycle(s): 2012 Ninja 250 Posts: 7	I don't believe T fitting on my bike is where the CA emissions fitting would be. The connection is on the vacuum hose labeled "vacuum hose to petcock". The hose labeled "Coasting enricher vacuum hose" appears to be directly connected from one end of the carb to the other, no T. Or am I misunderstanding the attached pic?

August 31st, 2022, 01:27 PM	#4
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	No you got it. Functionally same: 1. TWO vacuum ports, one on each carb 2. one port goes to petcock 3. one port goes to coast-enricher 4. one has T for CA emissions under tank You can put T on any vacuum hose. It's better to have configuration above with dedicated hose just to petcock alone. That ensures most vacuum for petcock without any interference from other devices sharing vaccum hose. If you end up with vacuum leak from cracked hoses or plastic nipples, it'll only affect coast-enricher and not cut off your fuel-petcock as well.