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Old 12-13-2009, 01:03 AM   #1
MODNROD OP
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Pod filters vs. airbox

I know the theory about airboxes, and I agree with 90% of them. BUT.....

IF I run the pod straight of the FCR, THEN I can use the airbox for much needed storage, don't have to worry about oiling foam filters as K&N don't make a drop-in for my model (coz I hate doing it, and I hate foamfilters, so there!), and a few other reasons that make no sense

Not wanting to be talked out of it, or led through the various pro's and con's, but would really like to hear from those who have done the job already and hear their experiences, for and against. Don't care about dirt and dust (nearly all road work), don't care about noise (bugger-all other people live out here anyway), but looking to hear about jetting differences, perceived loss of top-end due to restrictions, etc.

Gonna do it anyway, but nice to hear from others who do what they're told not to.......
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Old 12-13-2009, 02:54 AM   #2
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K&N's (or similar Pod filters) are good for performance - 95% of the time. Some 2-stroke engines (RD Yams) don't like them coz it upsets the airstream & back pressure pulses.

K&N's still need "oiling" with the special filter oil (K&N stuff is red) and also cleaning now-and-again.

If your bike has CV carbs, Pod filters can be a pain coz these carbs are not ideal for tuning.

If Pods are to be fitted to 'proper' carbs, then a bit of time & effort (along with at least a free flowing exhaust) should release some more power.

If the bike was standard and you have whacked on a better exhaust & Pod filters, then initially you could try going up 10% on the main jet. Every bike set up is different, so its only a rough guide.

For example, my '78 Z1000 is up from 1015cc to 1075cc, a gas flowed head and instead of 28mm carbs, i'm running Mikuni RFS36's, with K&N,s and a 4:1 Vance & Hines pipe. The std carbs are about 115 mains, but on the new setup I'm running 135 mains.

Also, you will most probably have to sort the "pilot system" out, either make it richer with the air/fuel screw or even up-size the pilot jet.

This is a bit of a messy about, and the easiest solution is to get it set up on a DYNO at a performance bike shop. GOOD LUCK
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Old 12-13-2009, 04:46 AM   #3
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Thanks for the input mate! I have run them on big 4's forever, coz old airbox's don't hold much volume, like 836 Zed's with 29mm smoothbores, etc. I've been told to expect a drop in top-end performance using a pod on a big single, which for me really isn't much of an issue coz they're pretty slow outright anyway, but I figured if I lose 2hp but pick up other factors elsewhere then that's OK.

I reckon if we can get 300rwhp out of 1428cc Kwaka's with FCR37/39's and pods, then they can't be too restrictive......that's 75hp per pot, way over what this thing will do.

I've seen pod's on XL600 streeters, some SM's, etc, just wondered how they compared to the modded airbox route, as compared by their owners/riders.
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Old 12-13-2009, 04:47 AM   #4
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Personally I've used pods and I think they are absolute rubbish. A good dusty ride and they are never the same, plus they are a right pain in the arse to get your mixture right.
I know you said you hate foam, but your bike will love it. Your choice though.
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Old 12-13-2009, 05:00 AM   #5
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Im in the godsilla camp to...I never use them, makes the bike/or whatever, way to picky on jetting. plus dirt has an easier way in....

you dont gain anything compared to the airbox performance wise. plus if you need your airbox for storage, get a fender bag.
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Old 12-13-2009, 10:14 AM   #6
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Pods are a waste of time on a bike that has CV carbs.
CV carbs like a relatively smooth undisturbed air source, such as what an airbox provides.

I put removed the aribox and put K&N pods on my 83 GpZ550, any cross wind or any time I was going above 80 mph that carbs would start doing all sorts of strange things.

I removed the pods and put the airbox back on it and no more strange carb problems.

For a flat / oval / round slide carb it won't be much of a problem.
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Old 12-14-2009, 08:13 AM   #7
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Dunno Gunsy, I had pods on a Kawasaki multi with Mikuni slides, and still had the same problems in crosswinds, the bloody things were just a pain. And when they got dirty I used the recommended cleaning stuff and also tried a few other creative methods but they never come properly clean again either. I actually had better results running an airbox without a filter element fitted.
I found then more trouble than they were worth frankly.
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Old 12-14-2009, 10:54 AM   #8
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I removed the airbox on my XT500 and put on a K&N. My engine stuttered and died from sucking water on a rainy highway in Northern Washington State. I'd never do it again.
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Old 12-14-2009, 11:20 AM   #9
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Wow, everybody seems to have something bad to say about pods. Well, my experience could not have been better. Used them on a twin carbed dr750 mounted via 10cm snorkels. It ripped to the red line, without any hesitation or loss of torque down low. Didnt seem to mind torential rain either. Only negative was their affinity to frequent cleaning (every 5k km in dusty greece).

What bike do you plan to install them on?
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Old 12-14-2009, 11:53 AM   #10
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I put one on my old DR650 (CV carb) when I was buggerising around with the rear shock on it (got sick of pulling out and reinstalling the air box).

I can't say I noticed a difference.
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Old 12-15-2009, 06:10 AM   #11
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Quote:
Originally Posted by mousitsas
what bike do you plan to install them on?
KTM 640 LC4 SM. Mainly (90%) used on road, but live in a dustbowl this time of year anyway! I've always used them on Jappa 4's with smoothbores or flatslides, jetted to suit each pot (middle and end cylinders), but was told by a tuner who's opinion I respect that I might have top-end power restriction issues on a big (first ever to me) single. Thought I'd ask around for the "road-test" of those who have used them, just as something to keep in mind after fitting.

Seems most people don't seem to like them very much!

Only downside I've experienced with multi's is more noise on the throttle, but my experience with multi's at least is quicker spin-up from low revs, and a better over-rev, but not a lot in it really. Spose I'll just try both, if I can't find any difference then I'll go with the pod just to be obnoxiously different
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Old 12-15-2009, 08:10 AM   #12
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Quote:
Originally Posted by MODNROD
KTM 640 LC4 SM. Mainly (90%) used on road, but live in a dustbowl this time of year anyway! I've always used them on Jappa 4's with smoothbores or flatslides, jetted to suit each pot (middle and end cylinders), but was told by a tuner who's opinion I respect that I might have top-end power restriction issues on a big (first ever to me) single. Thought I'd ask around for the "road-test" of those who have used them, just as something to keep in mind after fitting.

Seems most people don't seem to like them very much!

Only downside I've experienced with multi's is more noise on the throttle, but my experience with multi's at least is quicker spin-up from low revs, and a better over-rev, but not a lot in it really. Spose I'll just try both, if I can't find any difference then I'll go with the pod just to be obnoxiously different
I think part of the reason my experience was positive, is that a twin carb setup on a big single is less sensitive to intake setup than when you have a single carb. Another reason might be the tube i used between carb and pod. Intake snorkels are like exhausts when it comes to tuning. You can retrieve lost low end.

If you go pod, use the largest you can find and if in a very dusty place, wrap around a prefilter. KN calls them 'prechargers'. A large filtering surface area, apart from the obvious breathing advantages, enables the air to have a lower speed when going through the filter fabric, resulting in higher pressure inside the filter, better dust capturing and less chances to suck in water when it rains.
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Old 12-15-2009, 10:53 AM   #13
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If you are talking about the 640 LC4, they should actually work, but will make your bike very weather-critical. Ie. 10 degrees Celsius temperature change, will be sufficient to ruin the jetting. But if you're in the right region (temperature and altitude-wise), the bike will just rip.

Not sure if the FCR is the optimum-carb for a K&N but I would suggest, you also consider a velocity stack. There are some pretty good formulae based on the runner intake length calculations. This will give you the correct length of the funnel which will lead to optimizations in a certain (rather narrow) rpm-range.

Cheers
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P.S.: I am tuning Yamaha SR500s for classic racing...
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Old 12-16-2009, 10:24 AM   #14
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I've removed the airbox from my NX650 sumo and I use a K&N. Power increase was noticable. I like it, but I was very surprised how much the noise increased. Jetting has not been an issue, but I've kept the intake runner and installed the K&N where the airbox used to be so I still have a reasonable long intake track. I ride lots of dirt roads and I find the filter needs to be removed and cleaned as often as a foam filter. So it's important the the filter be easy to access. But I do find it's less of a pain than pulling a sticky foam filter out of a small air box.
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Old 12-16-2009, 10:43 AM   #15
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installed pods on my supertenere' 750 ...using the same original
rubber necks that were going into the airbox....
running them for a few years now...togheter with some after market "local shop"
made mufflers....
never an issue bike runs good ...and jetting never touched
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