Removing the USA-only emissions garbage allows you to fit a half-helmet and some 3/4-helmets under the seat. Even if you don't remove the USA-only emissions parts doing this alone gives you
To remove the charcoal filter & rollover valve:
1. Under the seat, remove the screws for the engine cover and remove the cover giving you a view of the engine.
2. From the charcoal filter (rectangular box), follow the tubing from the storage area, under the body-panel, and to the engine. You will actually be able to follow it back with your hand. At this point,
looking through the underseat opening to the engine you will notice that the tubing ends at the manifold.
3. From the rollover valve (round), follow the tubing back until you see the tubing when looking through the underseat opening to the engine.
OVERVIEW: One tube (left-side standing at the back of the bike and looking forward) runs from the fuel tank as an overflow vent and runs inside the left-side body-panel to the rollover valve in the storage
compartment. A tube connects the rollover valve to the charcoal filter (right-side of the storage compartment) and from the charcoal filter a tube runs along the right-side under the body-panel to the
manifold on the engine. The purpose of this system is to prevent gasoline fumes from escaping to the atmosphere. The European version of the BV500 does not have this additional emissions item.
4. What needs to be done is to cap off the connection at the manifold and allow the tube from the fuel tank to vent to the air. At this point, you might want to remove the side panels on both the right and
left side so you can see what you are doing. However, I left the side body-panels on.
5. From an auto-parts store purchase a air/fuel-line cap and a small clamp. Generally, various sizes of these caps and clamps are kept in a bin and they cost almost nothing. You want a cap that fits tight
and a clamp that will tighten it down securely.
6. At the manifold, snip off the old clamp, and pull the tubing off. Then install the cap and new clamp. It's that simple. See my photo of the capped manifold below.
ALTERNATE METHOD: I read where one guy disconnected the tubing at the charcoal filter and plugged it using silicon and a bolt. He then secured the tubing to the inside of the body-work. I felt more secure
capping the manifold directly.