Hey guys, I have a 2009 KLX250S that I recently bought used. I performed the smog removal on my bike the other day and the bike runs so much better now. I know removing it isn't supposed to increase performance (on a fully functional system) but I think my canister was just so fouled up that it was causing me problems. Apparently the canister needs to be replaced if the gas tank is overfilled and at around $80, I'd rather not spend money on something most people end up removing.

I have all three outlets on the OEM tank currently setup as vents (blue, red, and the original vent line) as this is what I've seen on this tutorial. But I've also read that another guy has the blue port plugged, so I'm not sure which is best.
Anyways, after removing the smog system, I now get a bit of gas coming from the RED vent line on the tank. It was only about a 1/4 of a teaspoon each time I stopped to check it but that'll quickly add up.
The tank was only about half full but I was riding through some whoops. While riding on the road, there doesn't seem to be any gas coming from the RED vent line.
So what is the RED port on the OEM tank for and is gas coming out of there normal for a tank that's only half full? I was thinking if it's the overfill runoff, maybe the rough whoops I was going through was just splashing some gas up into the overfill port??

 

Didn' do anything to the tank vents when I deleted my smog stuff. Just capped the vacume lines and the reed valve. Is that somehing specific to the California models?

 

Yeah it's for a California model. Both the blue and red lines from the tank run to the separator as seen here. I'm guessing you just removed the air switching valve which would require plugging one port on the airbox, one on the carb, and the reed valve.

Edit: I was reading the service manual and from what I read, I'm thinking the RED port should be capped and the BLUE port vented with a hose. For non-California models, the service manual only talks about the drain hose and breather hose. And for the California model, it says the RED is the fuel return hose. Here is the page I am referring to:

 

I'm still running stock exhaust, carb and CA smog. Removing SMOG made a noticeable difference? Did you do anything else at the same time? I was under the impression it changes nothing.

 

If anyone can prove they pick up power by removing smog hardware I'd love to see it. There is nothing that it does that detracts from performance other than its weight. I didn't bother removing mine because I didn't have any of the junk to plug it up. Just wasn't worth dinking with it. No gain.

On the CA bikes there is probably a charcoal canister hooked to the fuel tank breather so any escaping gasoline fumes are absorbed by the charcoal. Again, only the weight, no power gain.

 

The only thing I did was remove the emissions stuff. Like I said in my original post, "I think my canister was just so fouled up that it was causing me problems". When I said my bike is running better, I just meant it seems to start and idle better now. Also the bike used to have pressure in the tank and I could hear it releasing pressure whenever I would stop. I've not had any tank pressure like that since removing the CA smog stuff. The tank breather line used to go into the separator so having it fully vented may have helped.To be clear, I've not noticed any performance gains as far as HP or torque. The service manual says that overfilling the gas tank can cause fuel to run into the canister and when that happens, it needs to be replaced ($80 part). I don't know what the previous owners have done so I figured since my bike hasn't been running top notch that I would try removing it (it wasn't hard).

Anyways, I took it out one day and tried capping the RED port and venting the BLUE port. It runs good like that and I no longer have gas dripping on the ground. After about twenty minutes of riding, I removed the cap from the RED hose for inspection and about 1/8-1/4 of a cup of fuel came out. This is way too much fuel to be losing within a twenty minute ride so I'm going to keep the RED port capped and vent the BLUE port.

I found this in the service manual, "Liquid fuel is caught by a vapor separator and returned to the fuel tank.". And the previous picture i posted said that RED is the "Fuel Return Hose". So that would lead me to believe that the RED port is an input for fuel to travel up and back into the tank. So I feel that capping the RED port and venting the BLUE port is the correct thing to do despite what this tutorial says.

If anyone has the red port vented on their bike, check if you are losing any fuel from it while riding rough terrain.

 

I get it now, canister is crap. Yeah, you need to find if there is a way to "49 state" the system. Get rid of the canister and get it working. Wish I could help more with this. Maybe do a google search and see what shows up at other forums as well as this one. Maybe something at Thumper Talk. or the like.