Vented gas cap Harley Evo Discuss Vented gas cap in the Motorcycles forums; My 97 Road King has experienced tank venting problems. With a cap which breathes IN, my Mikuni bleeds under the accumulated pressure when I switch on the petcock. With a ...

[Moffett]

My 97 Road King has experienced tank venting problems. With a cap which breathes IN, my Mikuni bleeds under the accumulated pressure when I switch on the petcock. With a cap which breathes OUT, I have to open the cap occasionally when rolling down the road, to let air in and prevent fuel starvation.
The Harley parts counter gave me the "breathe IN" cap. I got the "breathe OUT" cap from an independent shop.
Is there a cap available which is vented in both directions, and fits the Road King?
Thanks.

[evoKENevo]

Is there such a thing as a "breath OUT" cap ???
And,what "accumulated-pressure" are you refering to ???
Meanwhile a "quick-fix" for a cap to breath "IN & OUT" would be to drill a small hole in the plastic above/around breather-valve...and CHEAP,too !

[frisco-rigid]

Ah yeah,, never heard of a breath out cap..

Supposed to vent in but still let a little of the excess built up pressure vent out..

The one time I drilled the vent,, gas came spewing out..
It simply creates an opening for gas to escape.. I guess it works for some..

Now I don't mess with em at all..

I glue shut the vent entirely.. Then I install a T-fitting in the top breather tube between the tanks..
I cut a longer tube so I can route it as high as possible up under the dash..

Alota the stuff I do is not for the regular rider.. When someone tries something like this you gotta be ready for adjustments specifacally for your application..

[evoKENevo]

Hey,frisco

You mentioned your fix for venting your tanks before...and it does make sense to me..but,I just was'nt comfortable with the idea of gas fumes escaping into the pretty enclosed area under the dash...with elec. switches,etc, in there...saw a boat "blow-up" from unvented fumes in hull one time,when engine was started...am I just being too paranoid ???

I got the idea of small hole in cap from Buzz in thread awhile back...gave it a try with a friend's bike after several NEW caps failed to vent...problem gone...and,no spillage...noting I made it a point to warn (extra) against overfilling the tank.

Hmmmm...speaking of fumes,etc...was'nt thinking about expanding gases in tank from heat,etc...as "accumulated-pressure" before...'nuther good call on your part...just never had a problem (noticed) with it,makeing a carb bleed,though...and,just another example of never being to old,etc.to learn and/or be reminded of stuff.

[47knuck]

I've heard of people drilling a small hole in the plastic liner in the bottom of the gas cap. Might be worth a try.