Build your own "dial-a-boost" boost controller, by Lorcan (pics by Ryan)                       

This is a basic two stage boost controller, operated by the horn button, or any other button. The first stage is normal wastegate controlled boost (7-10psi on the stock bike) the second stage when activated by the button can be pre-set to any level. This arrangement is/was sold by Mike at HPU and others, but all the parts are readily available from any hydraulic suppliers.

You will need:

1) an adjustable 2 port pneumatic regulator with 1/8" ports

2) a 12v DC 2 or 3 port solenoid with 1/8" ports

3) 1/8" hose barbs, straight and 90 degree, rubber boost hose, a hose T-piece, a 1/8" male/male adaptor to connect the solenoid and regulator together

4) JB Weld or similar, thread sealer

Here's a picture of two actuators (modified left, stock right). The actuator controls the turbo wastegate. Inside it is a diaphragm and a spring. Boost pressure enters via the nipple at the bottom of the picture. Once boost pressure exceeds the strength of the spring, the spring compresses, moving the actuator rod, which opens the wastegate.

The small pinhole on the actuator on the right is just to allow the diaphragm to move. You will need either to drill this hole large enough to take a hose barb fitting, or JB weld a fitting over the top of it. If you JB Weld it you run less risk of damaging the diaphragm. With the hose barb installed you can now allow a controlled amount of boost pressure to the other side of the diaphragm, adding to the spring pressure, raising boost.

Note: if you don't fancy modifying your stock actuator, 2 port actuators are available from Turbonetics.

Once this is done, connect the hose barb as shown to the regulator and solenoid.

        

Find a suitable mounting place (inside the fairing is good, or the space where the air filter used to sit if you use a K&N) where you can mount both and wire the solenoid via an inline fuse and easily accessible switch to the horn button. With the switch in one position the horn should function normally, in the other position it should operate the solenoid. You will need access to the regulator, so make sure you can get to it once installed.

Back the regulator right off to start with, then gradually turn up the regulator to allow through a few psi. If your stock system made 10psi and you allow 3psi through the regulator you should now have 13psi boost. Be careful turning it up as these regulators tend not to be linear. Always use a boost gauge and a lambda sensor (preferably on a dyno) to monitor your progress. We recommend no more than 15psi on pump fuel, air/fuel ratio should be 11.5:1 or richer when under full throttle.

CARRY OUT ALL BOOST MODS AT YOUR OWN RISK, BAD SHIT WILL HAPPEN IF YOU GET IT WRONG! IF IN DOUBT, ASK IN THE FORUM.