Gas cap line "T" fitting?

dkruitz · Aug 21, 2015

I'm in the process of familiarizing myself with my new ST, and saw a "T" fitting apparently vented to the air from the hose that runs from the gas cap down along with the carb overflow line.
Seems odd to me, any reasoning for what the "T" does?

Oldbikefixr · Aug 21, 2015

The hose directs gasoline vapor to flow from the gas tank through the re-circulation system where it is collected and released into the carb inlet when the engine is running. The little fitting on the fuel cap has a seal allowing it to remain stationary while the cap is twisted. If the seal is decayed it is venting to air...time for a replacement.

dkruitz · Aug 21, 2015

Question isn't about the cap, but what about the "T" down low near the alternator? In the parts diagram below, it's #30.

W0QNX · Aug 21, 2015

That T is in case the bottom of the hose gets plugged by dirt and gunk rain or standing water it still works. Air goes in thru the T.

John OoSTerhuis · Aug 21, 2015

ZIAMON said:
That T is in case the bottom of the hose gets plugged by dirt and gunk rain or standing water it still works. Air goes in thru the T.

That's always been my understanding all these years also.

the_gr8t_waldo · Aug 21, 2015

think of it as a vent...for the vent. and some people think mother Honda doesn't have a sense of humor.

W0QNX · Aug 21, 2015

John OoSTerhuis said:
That's always been my understanding all these years also.

I've rode with another rider that proved this as fact. He removed the T and when we rode in heavy rain for a while his bike starved of fuel and wouldn't run very well. We totally removed the line and the bike came back to life. Replaced it later with a T and all was well.

dkruitz · Aug 22, 2015

OK - I'll make sure both the vent line and the T-vent are clear. Thanks guys.

Al st1100 · Aug 22, 2015

I think air heads to the tank and any water coming in from the bottom of the hose would drain out the tee

W0QNX · Aug 22, 2015

Al st1100 said:
I think air heads to the tank and any water coming in from the bottom of the hose would drain out the tee

This magic T fitting is like gold for discussion.

I think it's totally the other way around! Any gas that overflows the tank heads right out the bottom and any air that 'vents" to the tank comes right in through the T.

Next opinion please...

Al st1100 · Aug 23, 2015

as the gas gets used up how does the air get in there to fill the void?

the_gr8t_waldo · Aug 23, 2015

the cap vents both ways

Gas cap line "T" fitting?

dkruitz

Oldbikefixr

dkruitz

W0QNX

Blacksheep Tribal Member

John OoSTerhuis

Life Is Good!

the_gr8t_waldo

W0QNX

Blacksheep Tribal Member

dkruitz

Al st1100

W0QNX

Blacksheep Tribal Member

Al st1100

the_gr8t_waldo