[exabrial]

Just wondering about these tank tubes. Do they vent to the same place in the gas tank?

I noticed that stock one of them goes to the big plastic airbox. I imagine this was to reduce evaporative emissions by burning the fuel vapors up. I also noticed one of them seems to go through some sort of PCV valve...

What I'm thinking about doing is T-ing the two connections together... Is this a good idea? Does anyone have more information on why yamaha has two breather tubes instead of one?

 

[bruce59]

I believe one is a roll over valve ... to cut fuel supply if bike is down.

 

[gman]

I T-ed them when I removed the AIS. The one remaining tube I ran along one of the frame front down tubes to the bottom.

 

[Grizzlon]

I did the same on mine. Dont notice a dif, but it looks alil bit cleaner than having the 2 lines

 

[exabrial]

Good Info thanks guys. I'm T-ing them but using the spare downtube for a PCV (aka a $5 Krankvent).

 

[alanh]

Just wondering about these tank tubes. Do they vent to the same place in the gas tank? I noticed that stock one of them goes to the big plastic airbox. I imagine this was to reduce evaporative emissions by burning the fuel vapors up. I also noticed one of them seems to go through some sort of PCV valve... What I'm thinking about doing is T-ing the two connections together... Is this a good idea? Does anyone have more information on why yamaha has two breather tubes instead of one?

If you have a non-CA bike there isn't any gas fume connections at all and the following applies.


The line that returns to the factory air box has a minature in-line chk valve that acts as a drainfor any residual oil build-up in the air box as well asreleasing any pressure built up in the box. This valve free flows to the tee (atmosphere)and is sealed by the engine vacuum. If you have a VBAK/BAK the tee is capped where this line was connected. Here's a thread: Unidentified "fuel" related line....


The2-linesfrom the gas tank are vent & overflow .... as stated by Bruce, 1-line connects to the Roll Over Valve, which is position sensitive,and the other is connected to the tee and directed to the ground vis the down tube.


Here is my solution keeping in mind that i have Churchey's VBAK:


Fuel tank vent hoses http://rswarrior.com/forums/p/26940/388030.aspx#388030


Vent & over flow lines coming out from under gas tank http://rswarrior.com/forums/p/110675/911692.aspx#911692