This is for all rvt lovers out there, enjoy
starting off the "free mods"
first off: do the flapper mod, it will make a world of difference
By disconnecting the vacuum line to the flapper valve in the air intake duct you can completely eliminate the hiccup at 6800 rpm & reduce the power dip we have all seen on the dyno runs between 5000 & 7000 rpm.
As the flapper valve is an air intake noise control device which is not used on the basic racer, but rather only on the street legal bikes where noise levels are monitored by the EPA. It is advised that you only do this mod to "race only" bikes.
Having gotten the legal disclaimer out of the way let's get back to the flapper valves function. The valve is partially responsible for the power dip between 5000/7000 RPM. The flap is normally open. If you disconnect the vacuum line it will always stay open. You can remove the flap if you like. although it shouldn't make much difference with the stock air box. The HRC and Moriwaki air boxes have a larger duct with no flap for the race motors. The flap closes at about 5500 rpm which reduces the intake duct about 65%. It opens back up about 6700 rpm. This is done to reduce intake noise on the road bikes. The mod is done by simply disconnecting the hose at the diaphragm switch & plugging the hose with a screw,bolt or whatever you find handy or aesthetically pleasing.
next "soft rev mod"
http://rc51.org/b2a15.htm
and the PAIR removal
http://rc51.org/pair.htm