As mentioned by bigdog, the lack of a fuel pump makes forced induction a bit of a problem in many cases. It can be done, but it starts getting pretty tricky even before you get too far into it.
The preferred option is to convert over to fuel injection, but this necessitates the need for a SEMS (Standalone Engine Management System) which consists of a computer and an array of sensors. Then you need to hook everything up (head temp sensors, throttle position sensors, O2 sensors, pressure sensors of more than one type).
Did I also mention your old bike probably doesn't produce enough wattage to run the new fuel pump and injectors and SEMS? Time to rework your charging system...
You could always stick with carbs instead of going with fuel injection. This will save you the hassle of switching over to injectors and a computer to run them. You're still likely to need a fuel pump though. Provided you just go with N2O, the pump only needs to connect to the injectors for the nitrous (wet system is going to be much more preferable to a dry system if you're running carbs).
If you want to go the turbo or supercharger route, you have two choices when it comes to carbs.
First, there's the draw-through system. This places a single, larger, carb upstream of the compressor and the fuel/air mixture is drawn through the compressor and pushed into an intake manifold. This system is the easiest to design and implement, but it also has a good number of drawbacks:
1.) Because only a single carb is used, you're relying on a good manifold design to ensure each cylinder is getting the proper mixture of fuel and air
2.) A carb large enough to supply the amount of fuel you'll need at WOT may also be too big to run well at low or even mid-range
3.) You may not be able to ride this bike in wet and/or cool weather. The amount of evaporation that occurs through that one big carb will cool the air. Sometimes enough to cause ice to form within the carb; which may prevent it working at intended. Stuck throttle is a possibility.
4.) Fuel in the incoming air charge will prevent the use of an intercooler
The second carb option is a blow-through design. This design uses a turbo or supercharger to compress the air before it gets to the carb. While more difficult to implement than a draw-through design, it offers a number of important advantages. Individual throttle bodies and carbs can be maintained, so low and mid-range performance is less likely to suffer. Additionally, the bike will be more tolerant of wet and/or cold weather. The major downside to this approach is the need for a fuel pump and a regulator system. The fuel pump is necessary in order to pressurize the carb bowls above atmospheric pressure. This is necessary in order to keep the charger from blowing fuel back up into your tank rather than sucking it into the cylinders. Obviously, a system of regulators needs to be in place to ensure the correct pressure is getting to the carbs at the correct time. If there is too much pressure then you're just spraying fuel into your intake. The carbs should only be pressurized when your turbo or supercharger is spooling.
For all of the reasons listed above, 99% of power modifications on these old bikes will end up being of the naturally aspirated sort. If you have deep pockets or you just really want to go for it, then have fun. Start a thread so we follow along.
