so bare with me for i am a noob. i put pods on my bike because i am looking for performance. it has a rather open 4-1 pipe. i assumed they would increase airflow and help with the exaust. would i get better performance by putting an airbox on? should i change the jets back too?
"Performance" may be an over used word, and it certainly has a very broad meaning which changes according to goals. For example, fuel economy can be part of a performance spec. Max power at red line can be a performance spec. Power available at "roll on" can be a performance spec., etc. While pods may indeed be "better" for a special purpose track event. It is clear to me that the stock induction is far better at the wide range of conditions/requirements found during street use.
First, Pods are not a supercharger. It won't stuff any more oxygen into the cylinder that the engine doesn't demand.
Oxygen and fuel are what makes the power. If you've seen engines that were mechanically altered and used pods, it wasn't the pods that made the engine more powerful. The pods may have enabled that particular engine to make more power though, as it's demands are now beyond what the stock air induction system was designed to supply.
The stock air box only presents increased "flow resistance" at engine speeds very near and above red line. Those speeds are only intermittently used on street bikes.
Past reports noted, at best, a 1-2 Hp improvement at or above red line for modified engines using pods.
It should be noted that "pods" are not a specification. There are many brands/styles and they do not "flow" equally among the brands and styles.
The SOHC4 carburetion is not adaptive like todays modern computer controlled systems are. Changes in exhaust back pressure effect cylinder scavenging and air/fuel charge replacement of what remains in the cylinder from the previous firing cycle. Carbs don't know about this, and Honda set the metering to be "in range" with the exhaust provided when new.
Similarly, the induction characteristics effect the depth of vacuum in the carb throats. It is the depth of that vacuum from either venturi effect or simply engine suction, that determines the rate of flow from a given fuel metering orifice. There is flow in the carbs because air is being used to equalize pressure between atmospheric and what the engine cylinder demands. In the tube between source and destination is a gradient pressure. For purposes of explanation, a 12 inch tube might have half the pressure differential midway in the tube. If you chop off the tube (like is done using pods) the midway point of the pressure gradient moves farther back toward the intake valve and away from the carb metering jet. The closer the metering jet exit is moved toward the inlet source along the tube, the less effect the engine source vacuum will have on drawing fuel into the carbs and this alters/leans the fuel mixture for a given jet orifice size.
Therefore, an induction system change can effect what the size of the fuel metering orifices must be to achieve proper air fuel ratios for "best power". Then there is the turbulence developed by any obstruction placed in air flow, such as filter media. Pods put all that turbulence and it's downstream effects right at the mouth of the carburetor where the variable-with-airspeed downstream effects can reach into the carb throat to the fuel jet exits.
As the carbs are not adaptive, best power must be set for an average temperature, and outside air pressure.
Temperature not only changes the engine's combustion efficiency, but the air, or more importantly the oxygen, density. Barometric pressure also effects the oxygen density. Honda engineers had to find the "mid-point" for all these variables, and set the carb metering to anticipate all the variables that would be encountered anywhere in the world, assuming the induction and exhaust preformed as the stock ones do.
Anyway, there is a "ripple effect" when you change a parameter in the induction system that alters the pressure in the carb throats.
The slide cutaway shape works differently at different air densities (think carb throat pressure). And, the whole range of mixtures provided by the main throttle valve between 1/4 and 3/4 positions that are determined by the taper of the slide needle profile length and shape.
Is it really such a surprise that the stock arrangement is better for the stock street engine than a change over to pods?
However, if it's really more noise you are after, loud pipes and pods sure make it "sound" like there is more power from the engine, even if "performance" has actually diminished.
Cheers,
