TOPIC:

Tuning carbs for pods.

"In Search of The Free Lunch"
Cycle World circa 1983 complete article in 7 .pdf files.

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Good Ridin'
slmjim & Z1BEBE

I have that info already and it is an interesting read about putting pods on CV carbs.  The results were most interesting in that HP numbers went down not up. 

Very interesting reading.  Thanks for that.

But it "SOUNDS" faster!  Who knew that the Factories spend thousands of dollars, and hours, designing and tuning/testing their machines? 

Mike

At least a couple of the members at ZRXOA did dyno runs with different configurations of intake filterage. The best numbers came from a slightly modified factory box with a low restriction filter like K&N. This was with both stock and mildly modified engines and an aftermarket exhaust. In fact, the single biggest gain, besides a turbo, was in changing the exhaust system. The biggest advantage to pods is easier carb r&r, and the opportunity to install a large storage box. I can carry a one gallon jug and a rain suit under the seat now.

And like arrogant dopes we were convinced we knew how to do it better !   But those "faster" sounding bikes were so cool.   

Hey we all saw the pictures of race bikes with pods and wanted our machines to at least look like them. Will say I found it somewhat less troubling to tune for pods on vm type carbs than  cv type carbs. 

But yes I agree that lots of time,money and research was spent to create a linear power band by moma Kaw and the other makers.  Not sure I ever thought I knew better than them, rather I wanted to see what I could learn and if there was a way to add to what they created. 

I would agree that with stock cams and compression any gains would be minimal, and it’s more cosmetic and for the sounds. However let’s not forget factory tune is a compromise to cater for varying gas quality and atmospheric conditions in different markets and to meet varying noise regulations. It also tends to be a “soft tune” to ensure longevity. Whilst HP gains on a stock motor may be minimal a good set up will sharpen throttle response 

The concept of a cheap power improvement is very simple.  If you can get more air into the cylinders you can add more fuel and develop more power at any specific rpm.  The way to do that is also simple.  Remove anything that restricts air intake or exhaust.  What complicates things is that a change in one part will have an impact on the rest of a circuit.  Exhausts are tuned to the engine.  Carburetors are designed for specific pressure drops.  Additionally there are regulations that must be observed; emissions, noise, etc.  In the end it isn't that simple at all but it's doable for someone with knowledge, tools and patience.  For those with no knowledge, tools or patience they can do more harm than good.

That's what I got from the article.

Absolute airflow is a worthy goal when chasing absolute power.  Some of the problem with pods stems from the fact that street bikes must operate clean in the range from just off (relatively low) idle through WFO.  The vast majority of street running is between 1/4 & 1/2 throttle, often somewhat less during steady-state cruise.  That's where driveability comes in, not to mention fouling plugs or running lean (or both) at typical street RPM.

Go to most any roadrace track.  Highly tuned motors meant to produce top end power above all else either won't idle at all, requiring constant throttle blipping just to keep running or, idle at RPM so high that  they would be near unmanageable on the street.  We typically hear highly-tuned vintage race bikes at Mid-Ohio and Barber that 'idle' in the 2,500 ~ 3,500 RPM range if they idle at all.  But they make lots of power on top, from 1/2 throttle to WFO.  Do that on an air cooled street motor & meltdown won't be far behind. Liquid cooling helps but even then, the cooling system has to be very robust when crawling through traffic at constant high idle.  Pods or velocity stacks make sense on race motors, because racers aren't concerned with street level driveability, instead favoring responsive throttle at race speeds.

We've tinkered with pods & always gone back to the stock airbox.  For us, pods are just more trouble than they're worth.  YMMV (pun intended).

Good Ridin'
slmjim & Z1BEBE