Those who are not familiar, please read the following Water Injection in General - http://www.dave-cushman.net/misc/mannject.html Water Injection in 2-stroke Exhausts http://www.suzuki-rg500.com/water.htm Intake In short, you can inject water into the intake tract in a very fine atomized mist, as the water goes from liquid to vapour it will absorb heat in the intake tract (latent heat of vaporization of water is among the highest at over 2200J or heat per gram). Also water helps to smooth out combustion by reducing peak pressures (detonation or pre-ignition) and increases the EFFECTIVE octane (not the chemical octane as water does not contain any chemicals). By means of a programmable CDI you can then alter the timing to allow the mixture to burn more efficiently (generally higher effective octane will allow a bit more timing to allow the mixture more time to burn completely). This results in a higher efficiency and power (many turbo applications use water injection) Exhaust Injecting water into the pipe will change the acoustic sound pulse allowing the powerband of the pipe to be broadened. Basically, if a pipe makes most of its power in the upper revs (6000RPM and up) one can benefit from water injection in the lower revs (3000RPM to 5800RPM, allow some RPM for exhaust to heat up again) and this will significantly increase the Torque. I have a 2006 YZ125, quite a lot of time on my hands to tinker with stuff and am studying engineering in school and will be specializing in race engine design. I would like to know if anyone can offer me any advice of how to control this system. I have access to a brake dyno, so I will be able to dyno tune the engine. I am going to be purchasing a programmable CDI unit, which will allow me to change the timing curves accordingly (I have been instructed to be extremely careful with this as timing adjustments are very critical especially in the 2-stroke). In order to introduce the water into the intake tract I am looking at possibly using a Dial-A-Jet system http://www.thunderproducts.com/dial_a_jet.htm These are unique in design because they activate the fuel (or water) flow by means of engine vaccuum as well as acoustic pulses from the engine (lean condition producing higher frequency sound waves -- pulling in more fuel, rich condition being lower frequency -- pulling in less fuel). It will need an external float bowl to store the water but this type of system seems to break apart the fuel (water) very well and would provide the proper atomization that I would need. As for the exhaust, I would need to use some type of controller which turns on the water at a given RPM and then shuts off the water at a given RPM. Many say that also a certain throttle position for activation would be beneficial as I wouldn't want the system to engage upon deceleration (when I do not require the power, it would just waste the water). Basically I would tap a brass jet into the exhaust and run a stainless line for the first few inches to keep everything from melting, run this to a very small pump (windshield washer fluid pump would work). I've seen these MSD water injection kits for jetskis, these are generally multi cylinder but I'm sure they would work. Just not sure how its able to read the RPM http://www.atlanticjetsport.com/index.php?l=product_detail&p=1391 Not exactly sure if this would be the best method on a bike, but at least an option. I have heard of CDIs with outputs that would allow control of a switch, but can not find any information on them. The one that I heard of was a 3D Wolf CDI but I'm pretty sure they're out of business. I have some experience with electronics and whatnot, but I don't really want to rig up a hall effect sensor and missing tooth amplifier setup just to get an RPM readout and still have to find a way make a processor read this and send a command to energize a selenoid. Does anyone have any ideas of how to control the water injection in the exhaust in an effective and hopefully affordable manner? I'm sure there is a simple way to do this, as even spark plug wire surrounding hour meters are able to provide RPM feeback. Please only post with helpful information, I am looking for some engineers inputs or people with this type of experience as I have posted this in the engineering and technology part of the forum. Thank you for reading all of this!