I dont want to go the nitrous route because of the cost and the stress it causes the engine. I was hoping to do something with a form of gas either butane, propane, or LPG.
This is kind of a dumb statment (no offense). Any kind of fuel power adder going to "stress" the engine because the point of a fuel based power adder is to casue a bigger and more efficient explosion in the cumbustion chamber. Adding any kind of power to stock parts is going to stress them. Most of Nitrous' bad rep comes from improperly tuned systems.
Cost wise power adders seem to run about the same in the long run, however I remember an article concerning nitrous vs other power adders and they said that the HP increase per dollar for nitrous was greater than for other power adders. You can get a NOS "Sneaky pete" kit from jegs for around $220 which should be enough for a 5 or 10 hp shot in a bike. The best part about a nitrous system is that you can turn it off and have a totall streetable motor (unlike a supercharger or turbo which will be running all the time).
the problem with Nitrous is that anything more than a menial shot and you need good rods and pistons (and rings). looking at building a nitrous motor it might just pay to go to a big bore kit instead since the cost for pistons and rods will be about the same as an off the shelf 836 kit.
personally I wouldn't wast my time with butane, propane, or LPG concoctions since the learning curve will be three times as high (there are drag racers who have nitroused cb750s and converted the cb750 to nitromethane, how many racers use an LPG kit) and by the time you are done it would have been three times the cost. Besides, from what I hear LPG kits are kind of a laughable thing in the countries that allow them (as in no hot rodder will take them seriously).
but hey it's your money and time.
