Pods Vs Air Box. Dyno and Road Testing

[koko64]

G'day fellas, I got back from the dyno.

The pods when compared with an open air box and stock length velocity stacks with same main jets and needle position gave the same 80hp. Peak torque was down less than a ft/lb, 62.43 to 63.29.

The dyno lines trace each other with very small differences. What stood out was that the pods made the bike run leaner below half throttle and richer from half throttle. The half and three quarter throttle runs were unacceptably rich 11-12! It was rich enough to start killing power.
My assumption about filter area was incorrect at higher rpm.

The open air box with short stacks was significantly stronger in torque and hp through the rev range than both the pods and open air box with stock stacks. 81hp and 65 ft/lbs but 1-2 more all the way through.

I went back to the open air box with short stacks when I looked at the a/f ratios as I believe this set up flows the most air and helps the runt of the air box litter work a little better. The a/f ratio was consistenly richer with pods at WOT than the short stack air box with the same jetting. The open air box with stock stacks was leaner than the pods until 6500 rpm when it too took a dive in the a/f ratio on WOT runs. They would both need a smaller main jet. Again rich enough to start killing power
causing it to flatten off the torque and power peaks. The short stacks let me run a fatter main jet to get the gains everywhere, while the smaller mains with the pods and long stacks restore the peak power, but without the thicker midrange torque.

With more fine tuning I could get another peak hp and fill the dips in the torque
curve. Just matter of tuning.
So much of muchness. You aren't doing much harm running pods, just be prepared to tune. I would run pods over an open air box and stock stacks and tune accordingly. If I were to run the open air box I would definately shorten the stacks. This gave the thickest power and torque curves. Imagine what a bigger air box would give.
Forgive the scrappy report, its from a smartarse phone as the pc is down.
As for now, those K&N 1750s have been put back in their boxes for the big day of MBP style heads and split singles...(one day).

[greenmonster]

Thx f sharing! 

Maybe you`ve killed the neverending pods/box debate..... 

[ducatiz]

Now put some short manifolds on with split FCRs and tell us.... :-)

[koko64]

After some more ruminating over the dyno sheets, I noticed some characteristics of each set up.

The air box with stock stacks and pods appear more sensitive to any over rich points in the a/f ratio. It seems that those set ups required a more precise jetting with less room for error. The short stacks seemed to tolerate both rich dips and lean bumps in the a/f trace without harming the power and torque curves.

The pods ran with the most rich a/f trace on the same jetting at WOT. The pods run richer at WOT and above 1/2 throttle hurting the torque peak, but below 1/2 throttle run leaner and wanted more fuel/less air. I had to experiment adjusting the slow air jet and IMS to get rid of a lean condition from 1/8 to 1/4 throttle. I have to say, this was opposite my expectation, considering the pods have 20-30% more filter area. I really thought the pods would lean out the top end. However, the pods do not have a nice bellmouth/velocity stack type radius inside. It's pretty basic in there. The pods combined volume would be significantly less than even the runty carbed air box.

Now I have to decide if I can tolerate the extra 1.5 kilos I put back on the bike with the air box or continue to tune the pods set up. I suppose I have to wait for j v to start producing a carbon air box! Maybe an air box extension that can be clipped to the existing air box going up to the height of were the snorkles would be on a stocker..

In the end, between the stock long velocity stack open air box and pods, there was very little in it. Both wanted a smaller main jet.
The open air box with short stacks gave the best performance. It allowed a bigger main jet to support power over the rev range at WOT without choking the top end power or peak torque.

[koko64]

Now put some short manifolds on with split FCRs and tell us.... :-)

I'm keeping the 1750s in hope of doing that one day. Just a little keepsake for the future..

[SwampMonster]

Thanks for the info/update I don't pretend to follow you 100% but I understand plenty enough to make a decision and leave the tuning to my local Duc shop. Thanks again gotta love the cold hard facts.

[koko64]

Thx f sharing! 

Maybe you`ve killed the neverending pods/box debate..... 

Gday g m

How did you find it tuning the pods? Your M900 looks like it has pods from the picture.

[greenmonster]

i actually left it to a skilled tuner w a Dyno.

Most fiddling done w idle & off idle response.
No good idle yet w either 55 nor 60, but 1.5 half turns on air screw I find really good f off idle response.

[koko64]

That's interesting. The air box with short or long stacks wanted 1.5 turns on the slow air jet screw, 1/2 a turn on the idle mixture for best response. I run a 52 slow jet for easy cold starting, thats why the IMS is only 1/2 a turn out,. Ideally I could use a 50 slow jet, but with no enrichening/choke circuit and cold winters here (not as cold as where you are!), the 52 slow jets help.

With the pods I needed the slow air jet screw turned in to 1 turn to avoid an off idle lean spot. The pods required me to maybe go a richer, thinner needle root diameter.

Conversely,I needed 160 main jets with the pods and long stacks/air box, but 165 main jets with the short stacks/air box.

Both long and short stack air box set ups worked well with needle position 4, but I could have gone to needle position 3 with the pods.

A race car tuner I know told me we have strange fuel here, so I don't know how relevant my jetting is.

[greenmonster]

Think I have needle in 4th, 162.5 is my mains.
Pods w Kämna stacks.

[koko64]

Very similar jetting to be sure.

The Kamna stacks sound interesting. Can they be used with the standard air box?

Ideally I would like to use some stacks like the blue Keihin ones in a nice carbon air box. Does Kanma make air boxes?

[greenmonster]

Maybe they`ve done one-off boxes f their specials.

This is what I have:
http://www.kaemna.de/cms_en/katalog.htm?&view=artikel&artikel=1012
My friend bought FCR kit from them, he used airbox and these where left over so I guess they don`t work w the box.

[koko64]

The site says those adaptors fit the stock air box.
They look like a more radiused, "ported" version of the Keihin air box adaptors. I wonder if they work better.

[errazor]

However, the pods do not have a nice bellmouth/velocity stack type radius inside.

May be thats the reason the pods rich out on WOT ?
KN have filters with velocity stack built in.

[koko64]

For sure a good velocity stack in the pods would have to help air flow. Are the Kaemna stacks usable with other pods or only one type? I would like to use something like that in a custom air box.