Gas tank questions

[frank88]

I've just removed the gas tank in my truck to clean it and replace some crusty lines and I have some questions regarding which pipes do what. Is this right?

 

I'm fitting R1 carbs which don't have a fuel return, so do i simply block off number 3 in my diagram?

 

 

Can i remove the evaporation canister thing and just run a line from the stock point at the top of the filler hose to number 1 on my picture?

 

 

Also, this cap is vented right?

 

Thanks,

Frank

 

[Gery]

I don’t think that that is a vented cap.  My original cap looked like that and was not.  The venting,I believe, is through the evaporation canister.  My canister was removed by a previous owner.  I tried the return hose idea, but it didn’t work because the system was now closed...so no breathing.  This is a problem for various reasons including adding stress to the fuel pump, hoses, etc.

I dealt, inelegantly, with the breathing problem by drilling a 1/8” hole near the center of the cap. ( I put a small band-aid over the hole with the cotton part on the hole itself....to ensure nothing easily goes in).  Many full tanks later, still no difficulties and don’t seem to have spilled a drop.  

 

 

Other readers— I have have a question too, though.  When I had ny tank off, I was going to redcoat it.  One of the lines (I assume it was the fuel out line) extended to the bottom of the tank and had a cylindrical expansion on the end.  My old British motorcycles have a copper mesh filter screen at the outlet .  Realizing that the coating would foul this end piece — and needing to get the truck back on the road, I just skipped the internal coating.  Question is:  what is that enlarged cylindrical part?  A filter?    Easily removable?  Necessary?