if you cant find a small enough size tube, then get the smallest you can find. then if you are careful and have a drill you could drill the hole that is already there and widen it to make it fit
1. buy the tubing
2. take the filter out of the tank with long needle nose pliers or just pull the line all the way out and then shake it out in to your hand.
3. get a drill bit that is the same size as the tubing
4. carefully widen the hole with the drill (make sure not to drill at an angle because then you are going to have to fill it with some putty that can be used with gasoline, that wont dissolve).
5. then when you are putting the line that is supposed to have the filter on it, push it out of the top tank and put the filter on the. the filter on.
6. then push it back in to the tank.
7. on the out side of the tank try to put the lines on the stems by the primer button. if it is to big my cheap suggestion is to use zip ties (if they go on loose well i don't know because it worked for me, so i didn't need to do any thing else) it may be complicated but it worked for me. i hope this helps.
chief2thewetbutt, July 2009