My buddy has a Kawasaki Mean Streak running the Vulcan 1600 V-Twin (fuel injected). This is a great bike, but it has the most convoluted intake system we have ever seen. Basically it uses a snorkel to draw air from between the top of the engine and the bottom of the seat, and sends it into a bowl on the left side of the frame. The air enters the bowl from the upper part of the backing plate and moves through a circular (donut shaped) filter element that is sandwiched between the front of the bowl and the backing plate.
At the center of the filter there is a hole in the backing plate that connects to a tube that allows the air to pass through the frame (and the “V” of the engine) to another bowl on the right side of the bike. The air enters this bowl from the bottom/center of the baking plate, moves across 2 air bypass solenoids, and finally hits the butterflies on the TB which are located at the top of the backing plate.
The plan is to use a mod pioneered by a member of a Kawasaki forum (Google “Caddman Kit”) wherein the snorkel is blocked off and 9” air cleaners replace the bowls on both sides of the bike. Aside from blocking the snorkel, the backing plates are left stock, so some air will still enter from the left side and go through the tube, but the majority will be drawn from the right side. This should reduce pumping losses associated with the complex path of the stock system, and provide a colder/denser intake charge.
While doing a little more research we found that some people claim this mod is unsafe without integrating a standalone engine management computer. The reasoning is that the increased air flow will cause the engine to run lean. This confuses me for a couple of reasons:
(1) while the bike does have an aftermarket exhaust, it is not a “scavenging” setup, meaning the exhaust gasses are not being pulled out of the cylinders. Likewise, the modified intake has no “ram air” properties. Pumping losses are reduced, but since air is not being forced into the cylinders this should not cause the bike to run lean.
(2) While the intake charge should be marginally cooler than it was with the stock setup, it will be far less than what one would encounter with changes in ambient temperature. Obviously these bikes can be used on both a 50 degree day in October and a 100 degree day in July without intervention. They can also handle altitude changes with stock fuel mapping. This is why fuel injected engines have mass air flow sensors, right?
While I certainly admit that software designed to take advantage of these mods would result in more power and better delivery, I do not understand how the stock programming could cause any damage.
So… what am I missing?
(Edited for readability)
Last edited by Orangebingo; 08-30-2012 at 09:21 AM.