A good question, but amateur. Just bought a 1999 CBR600F4, and it's apparently MISSING the fuel tank breather tube... very strange. I'm guessing the owner or a mechanic took the tank off once and forgot to put it back on...? It's a large part, so that's doubtful. Maybe it just fell off over the years...

I have the 49 State/Canada carb'd model, not the Cali-emission model, if that makes a difference. Is it normal for this type of motorcycle to be missing the fuel tank breather tube? Also, what exactly is it used for? I'm assuming pressure relief, but again, I'm an amateur.

Thanks much!

 

 

The fuel tank breather tube is there so your tank can breathe as fuel is used the air has to come from somewhere so you do not collapse the tank. If the line runs down to the bottom by your swing arm make sure you in stall a T inline about midway. Reason is that if you were to ride in the rain and did not have the T the water would get sucked up into tube and into your tank as the fuel pump would override the pressure it would take to draw the water up and in the tank.
Not so with gravity fed carbs then the water in the line would just stall the bike and then drain out then you can start the bike and do it over again been there done that.

 

Thanks for the informative reply roboto. Makes sense why it's needed, a "duh" moment for me.

The inline "T" you described looks more like a 90* elbow in the images above, with two ends. Where would the third end of the T go in your description?

Also, what sort hose and inline T/90* would work? I think "Tube No. 1" is the type of tube, whatever that means. Bike bandit has the OEM parts, but it's expensive. Know of any cheaper replacements?

 

Mine is like a 90 and its like 1/4" line I think, you can get that at any parts house like autozone.

 

Any special name for the tube material? Or just a "No. 1 rubber tube"?

 

It's just bulk hose. You need to know the inside diameter and the length you want.

 

Thanks. I'll just order some stuff online.

 

Go to autozone or some-such. They sell it by the foot. Instant gratification...

Ern

 

Maybe I'm pushing my luck here, but any idea if they sell 90* elbows and hose clamps to go along with it? They're closed... otherwise I would call. Just wondering, I'll call tomorrow anyway...