breather tubes where do they go

athersych · Post by **athersych** » Tue Jul 14, 2015 8:27 am

hi on a rebuild and just need to know where the pipes go, the one to the breather on the tank has a t piece and a pipe coming off it where does this pipe go to

richyrd5 · Post by **richyrd5** » Tue Jul 14, 2015 6:52 pm

to the airbox top on the left!

Post by **RickOliver** » Wed Jul 15, 2015 7:06 am

If you mail me I`ll ping you a copy of the official factory routing diagram...

ricknc30@gmail.com

Rick

Post by **Swingarm** » Thu Jul 16, 2015 7:55 pm

Spooky, I spent the today going through breather pipe routing myself

Rick, I've mailed you to kindly ask for a copy of the routing diagram

I did try to use the digram in the Document Library on this site's homepage but the images are not very clear

I'm pretty sure the pipes on the T don't pick up from the connection on the left of the airbox! That's a seperate single pipe, I think

A question I have though is that of the pipes on the T, one seems to be the tank breather, the other seems to drop to just to the side of the clutch cover and the other seems to go off down to the sidestand - what's the point of having two open pipes? If this is the case could you not have one pipe that routes from the tank breather to under the bike?

athersych · Post by **athersych** » Fri Jul 17, 2015 2:03 pm

that's what ive come up with as well swingarm

Post by **Swingarm** » Fri Jul 17, 2015 9:43 pm

So Rick kindly explained why this might be - without stealing his thunder I'll give it some time for him to respond

My (reluctant) thinking is that if a Honda engineer thought it prudent to build it that way, I'm not going to make things better by changing things too far - cue outrage from all the special builders out there

Post by **Neosophist** » Sat Jul 18, 2015 5:26 am

It's just over-engineered.

I believe the reason is if the bike falls on itside the overflow can be blocked off, but if there is one each side it wont block?

Post by **Swingarm** » Sun Jul 19, 2015 9:08 pm

From what I understand the two open breathers on the T exit on the same side, albeit one upfront at the clutch cover, the other more rearward by the sidestand

Rick explained the two breathers from the tank as an "anti-siphoning" measure. Meaning if only one pipe was in place exiting the tank, any low pressure on the end of the breather could potentially draw fuel/create low pressure in the tank. With an extra breather, any low pressure on one pipe is balanced by the other with no draw on the tank conection.

That kinda makes sense to me although I don't see why you'd need an extra ~80cm pipe running all the way from around the choke lever to the sidestand... Sure, perhaps you don't want the extra breather opening close to a hot engine, or doubling plumbing to the same exit point... Over-engineering as you say??? Perhaps. Although I'm pretty certain someone made a career from spending 9-5 making these decisions :)

breather tubes where do they go

breather tubes where do they go

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