So you got a Californian or Canadian XR650L and wondering what this whole unsightly assortment of hoses and a canister on your bike is? Apart from sapping some power, this system is an air injector so that the bike meets EPA standards but robs the engine of its true grunt.
 
Remove those parts and shave over a pound off your bike using this Smog Delete Kit. There'll be no more popping on deceleration and a much better throttle response.
 
The two block-off plates for the cylinder are machined out of billet aluminum, then black anodized and the large plug for the hose coming from the airbox. It also includes 4 smaller plugs for the other hoses.
 
Straightforward installation: block holes and hoses you unplugged and re-route the crankcase breather hose to the airbox. Done!