4T Carb External Tubes Mystery?

[bigbird2]

I have a mystery question you may be able to help me with on my 2009 Evo 3004t that I bought used.

This weekend the float stuck open/down for some reason and gas was coming out. This was eventually fixed just by the old trick of banging on the float bowl with a tool

However in the process of investigation, I took off some of the things like the air box, etc. for better visibility and found an external hose configuration that was where the gas was coming out that I don’t understand. This is from memory but I THINK it is correct:

There was a slip on fitting for a hose that came out of the right side of the carb near the rear at a height just above the center of the main air intake and angled down. It had a black rubber hose attached that was several inches long that went down near to bottom of the carb under the main air intake area.

This black rubber hose slipped on to what once was a plastic “T” fitting except that one side of the “T” was broken off so that it was effectively a 90 degree angle elbow with an extra opening to the atmosphere near the corner (where the broken off part would have been). This is where the gas was running out.

The remaining branch of the “T” fitting had a clear plastic hose on it that ran back up along the left side of the carb (near the back) and onto a slip on hose fitting that came out of the left rear side of the carb up near the vacuum diaphragm at the top.

I couldn’t find any hint of a hose that would have once been attached to the branch of the “T” that was broken off???

After thinking of this I wondered if the “T” was some type of mod the prior owner added? as that would explain why I couldn’t find a hose that once went on the missing branch?

The bike runs fine as configured (with both of these hoses going down to the “T” and being open to atmospheric pressure so I guessing they are both just VENT lines?

The various parts and shop manuals don’t appear to address any of these external carb lines so I thought you folks may be able to help me? OR maybe you can point me to a source of a picture, etc. that shows these external tubes?

THANKS!

[neilnh]

From memory on my rev 4 one goes to the airbox and one goes to an engine breather will check when I get home

[bigbird2]

Thanks for the reply.

I have one large hose that goes from the engine to the air box (crankcase breather?)

I also have a small hose that goes from ? forward into the air box.

These 2 hoses use all the hose holes in the airbox.

Thus I don't THINK the hoses I'm asking about are airbox related?

[carl ekblom]

Yes, the large tube is the crankcase breather and the small one goes from the hot start valve to the air box. This tube isn´t reallly needed. If you like you can block the hole in the airbox and take the air directly from outside into the hot start valve.

The small mystery tubes from the carb are all air vents from the carb. The T-tubes are used to reduce the number of tubes going down behind the enginee where they end.

The large air vent from the vaccum chamber at top of carb should be blocked.

Hope this helps.

[trialholic]

The large air vent from the vaccum chamber at top of carb should be blocked.

Why?

[billyt]

The large air vent from the vaccum chamber at top of carb should be blocked.

Why?

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Because it is for a multi carb set up such as four cylinder engine.

There should be a little black cap on it.