Fuel Overflow/ Carb Breather Snafu

[speedysmurf]

I'm sure someone has noticed the fact that the overflow from the Fuel Tank is routed straight into the Carb Bowls?  But can anyone explain why??

I was having the hardest time jetting my bike to altitude and some minor mods (Yosh Exhaust and K&N).  I would get it running well and then it would rain or I would fill my tank up a little to much and some fuel mixed with whatever dirt and dust was around the filler cap would go down the Overflow tube and all of the sudden it would run like shaZam!.  I've gotten really good at rebuilding the carbs.  

Then I realized that any dirt or water that found its way into the ring around the fuel cap eventually was flushed straight into the bowls sans filtration.

So as an effort to correct this engineering anomole, I disconnected the upper "tee" on the carbs from the overflow tube on the bottom of the tank and turned it so that it pointed down, then I wrapped a small piece of Hosiery around it with a zip-tie for what is essentially a Carb Breather filter.  Then I routed a new piece of rubber tubing from the tube on the bottom of the Tank to the lower part of the frame where the Airbox Drain tube goes.

This has fixed my constant tinkering and allowed me to enjoy my bike rather than be frustrated with it!!!!

Hopefully, this will have helped some who are experiencing similar problems.  But if someone could explain why it was done in the first place I would appreciate it. :guns:  

[Dom]

Fuel tank overflow to top T on carbs? Not mine...  My fual overflow goes down  
by the rear shock to nowhere.  The top T has a tube attached to it that goes to the same place as the overflow...everything runs fine so I ain't sweatin' it.

[Kerry]

What year is your bike?  If it's pre-'01 and non-California then it should have been set up as shown on my Fuel Hose Routing page.

The drain hose you're talking about - is it the one that connects to the center of the underside of the tank?  Mine is routed so its open end comes out near the right footpeg.

[Rema1000]

But if someone could explain why it was done in the first place I would appreciate it. :guns:

As you noticed, the fuel overflow should just drain; not connected to anything.  And the top T on the carbs is connected to a hose which just lays over the airbox; also not connected to anything at all.  Often there isn't even a hose there; just the T connector.

I'll take a wild guess why yours were connected together:  someone got done reassembling the fuel system, and had one extra hose (from the tank) and one extra T connector on the carbs.  So they decided that the leftover hose should probably be connected to the leftover T connector!