First of zstoldt, sorry to bring debate into your thread. Scottly says true. Start with trying it out. But at the same time, I have never seen a direct to stock carb pod setup regardless of re-jetting that actually ran proper. Lots of people can get them working, but working is not running. It is interesting because in my vintage car groups, people run IR sidedraft webers all the time. And nobody would dare run without their stacks. It simply never works. But with vintage bikes, outside of the race built and mesh over velocity stacks, I never see people with their horns and pods....
Bull#$%*!!! What happens BEFORE the venturi matters not, or very little, with regards to "ram" tuning. Any pressure wave is reflected at the first obstruction on the path back from the intake valve to the carburetor, which will be the venturi in this case.
I never said ram tuning doesnt matter. It doesn't matter in this topic. Removing the airbox and their runners, then replacing them with pods affects airflow into the carb. Thereby disrupting the whole system. The physical properties of the ram had not changed. Which carries into the second quote.
What? This does not make sense. Essentially.
Makes perfect sense. An engine is an air pump. Plain and simple. It's rotational speed is governed by nothing more than power vs load. Engine is 750cc, it will draw in 750cc of air. Depending on the restriction, the density of this air changed. At density it needs a volume of fuel for proper mix. Airbox and filter do create a vacuum, changing the atmospheric pressure before the carburetor, but not a whole lot.
The acceleration of the air through the venturi is what creates the real vacuum to make this work. Throttle and choke also create vacuum cause when you have an air pump with restricted inlet, you get a vacuum pump. When the air is turbulent though, this gets disrupted. The key to the jets working is a smooth airflow over the port. When you have ugly pulsing and turbulent air, it doesn't work right.
Try it for yourself. Take a bottle and put a piece of dry ice in it, or hot water, or whatever. Blow pulses over top of the bottle neck and watch the CO2 draw out of it. Do the same thing, blowing same amount of air, but blow giving the rasberry. Doesn't work for crap.
So pods. They do not change displacement, they do not change the ram. They do not change the airbox vacuum (significantly), they do not change choke, throttle or jetting. They only change the airflow in. So if the amount of air the engine is drawing in for a set RPM/throttle position has not changed, then why would the fuel it needs change? It really doesn't. With exception of pods without sufficient CFM, every pod conversion I have seen has mentioned needing larger jets. This means that the fuel draw isn't working as efficiently.
For your carbs, if you have mechanical sliders, then it really isn't so big of a deal cause you can adjust those. With vacuum sliders, then it causes all sorts of problems. Pods on the CV carbs without the horn just run terrible. Nothing wrong with pods, they just need to be tuned. In fact, the first CV carbs had essentially a pod filter. They just had the horn built into them. Hundred dollar a piece air filters for my 450...
Single air filter for the carb, Keihin carburetors. CV carbs weren't found on the SOHC4s outside of the 81 and 82 650 if I remember right. Key is laminar flow. Cars, boats, bikes, paint guns, bug sprayers, car wash soap sprayer. They all work on the same mechanic to draw in fluid. And they all stop working if they do not have proper flow. Is fluid dynamics. The fact it is a motorcycle carb doesn't change this.
