Topic: Pod Filters...K&N vs. No Name

[Zorro]

I just bought a Carpy 4to1 exhaust and I'm looking to "attempt" to run pod filters.  Should I buy the 4 K&N filters at $180? Or, should I buy no-brand-name off ebay for $30 ("W" logo on chrome cap)?

Thanks in advance!

[nobody]

K&N, they're going to function far better than crappy emgos or whatever. Good luck tuning those right though, I tried to get my pods right but never did so I switched back to the air box, seems to be pretty normal for pods.

[Zorro]

K&N, they're going to function far better than crappy emgos or whatever. Good luck tuning those right though, I tried to get my pods right but never did so I switched back to the air box, seems to be pretty normal for pods.

Do you still have your K&N and do you want to sell them?

I got a guy who says he can easily get them running.  Fingers crossed.

[Terry in Australia]

I've just gone thru a similar situation, I've gone back to OEM carbs on my highly modified 836cc engine after I had numerous problems with 29mm CR carbs. With the OEM carbs re-fitted, it ran OK (but a bit lean) with 110's and the OEM airbox, but I bought a set of K&N pods on EBay so I increased the main jet size to 120, but that was way too lean and wouldn't rev under load past 4000 RPM without pulling the choke on. I've since increased the main jet size to 132.5's, and that seems to have cured the problem, but I won't know until I get a chance to ride it this coming weekend.

The OEM airbox is a good item for stock engines, but most race bikes run with no airbox or air filters of any description, so there's no reason why you can't tune an engine to run well with pods, and in normal road riding situations, you need some sort of air filtering system to keep the rocks and small animals out of your engine. But don't buy "No name" pods, I had a set and they were poorly constructed crap with little or no filtering. K&N's are expensive, but worth it. Cheers, Terry.  

[Zorro]

I've just gone thru a similar situation, I've gone back to OEM carbs on my highly modified 836cc engine after I had numerous problems with 29mm CR carbs. With the OEM carbs re-fitted, it ran OK (but a bit lean) with 110's and the OEM airbox, but I bought a set of K&N pods on EBay so I increased the main jet size to 120, but that was way too lean and wouldn't rev under load past 4000 RPM without pulling the choke on. I've since increased the main jet size to 132.5's, and that seems to have cured the problem, but I won't know until I get a chance to ride it this coming weekend.

The OEM airbox is a good item for stock engines, but most race bikes run with no airbox or air filters of any description, so there's no reason why you can't tune an engine to run well with pods, and in normal road riding situations, you need some sort of air filtering system to keep the rocks and small animals out of your engine. But don't buy "No name" pods, I had a set and they were poorly constructed crap with little or no filtering. K&N's are expensive, but worth it. Cheers, Terry.  

Very informative post.  Looks like I'll be springing for KN.  Do you have a good site that sells these?

[KingCustomCycles.com]

I have had no trouble tuning pre 77 carbs with cheap pods and the filtration never bothered me since running open velocity stacks is also common.  It also doesn't bother me to bore and re-ring engines due to ingesting dust and dirt. Comparing racing applications to the street is sketchy since the demands are so different.  Street is all about idle, transition, steady partial throttle operation and quiet decel.  Strip is all about the top end and peak power.

[Spanner 1]

180 dollars U.S. for pods  ...... go to the Pub for a good nite out with the lads  and pay the tab
P.S. ... Stock airboxes rule.... IMHO.

[Terry in Australia]

Street is all about idle, transition, steady partial throttle operation and quiet decel.  Strip is all about the top end and peak power.

Are you talking about drag racing or road racing mate? Drag racing is certainly all about top end power, whereas roadracing requires good bottom end and midrange torque for getting out of corners fast, as well as top end power, not that dissimilar to a tuned streetbike application. Cheers, Terry.

Very informative post.  Looks like I'll be springing for KN.  Do you have a good site that sells these?

Thanks mate, I was lucky to score some "as new" K&N pods for 50 bucks for a set of four on EBay a couple of weeks ago. Ape sells their own brand of pods for a reasonable price (much cheaper than K&N's) and if APE sells them, then they've got to be pretty good, but if you can find some K&N's, even better. Cheers, Terry. 

[eideteker]

These are about what I have (the 35mm ones), and being a total bike/carb newb I had no trouble tuning for idle, cruise, WOT, etc.  Just saying.

[cb650]

I run emgo's on my 360 np's.  Have unies on one of my 650's np.  The unies dont like oil though. Guess thats why the package says not to oil them.

[nobody]

K&N, they're going to function far better than crappy emgos or whatever. Good luck tuning those right though, I tried to get my pods right but never did so I switched back to the air box, seems to be pretty normal for pods.

Do you still have your K&N and do you want to sell them?

I got a guy who says he can easily get them running.  Fingers crossed.

I do not have them any more. I hope your guy knows what he's doing because otherwise you're going to lose a lot of low end power and end up with a midrange flat spot without increasing any top end power. That's what happened to my bike, it looked and sounded a little better but it performed quite a bit worse.

[Terry in Australia]

It's not that hard to get them right. Obviously 30 plus year old carbs are a lot less adjustable than say, modern electronic fuel injection, but all you've got to do is play with your main jets and/or your needle positions to get them where you're happy with them. if your mechanic has an exhaust gas analyser this will make it a lot simpler than doing numerous "plug chops", and if after he's got it in the ball park you can spring for a dyno run as well, you'll get it perfect.

As I said before, the OEM airbox works great, but I suspect only because it works as an additional "choke", richening up the mixture, by reducing air flow. Cheers, Terry.

[KB02]

One thing to keep in mind is that the K&N filters have a velocity stack design inside the filters vs. no-name filters do not.

[Terry in Australia]

Took my CB750K1 for a ride today, with 132.5 mains and K&N pods I saw 120 MPH @ 8500 RPM in 4th gear. Of course it's not a stock engine, but a highly modified 836cc lump, but I have to say it's running better than it ever did before, when I had the 29mm CR carbs fitted. I'm happy!  

[Geeto67]

As I said before, the OEM airbox works great, but I suspect only because it works as an additional "choke", richening up the mixture, by reducing air flow. Cheers, Terry.

actually Terry it is because the airbox is a plenum of still or smooth air and the air box rubbers are velocity stacks. If you look at a fuel injected engine they usually have a similar plenum but it is after the throttle body. The rubbers that mount the box to the carbs are actually velocity stacks designed by honda for improved flow into the carbs. A lot of low budget racers I know run just these rubbers on their carbs instead of custom velocity stacks and have an easier time with the jetting and adjustments than if they ran generic stacks or nothing at all. There is actually a science to the stacks and airflow into a carb - a carb taking in roiled air will underperfom as compared to one where the airflow is predictable, linear, and smooth. The stock stacks are tuned for overall rideability, based on length, funnel transition, etc....increasing or decreasing the length can move the power peak up or down the RPM range and the funnel transition and the inlet size can control the speed of the air into the carb making part throttle operation smoother or choppier.

for those who want to know more start with the wikipedia entry:

http://en.wikipedia.org/wiki/Velocity_stack


I don't know why people bother with individual K&n filters when they can make their own air box that looks better and works better and you are gauranteed you won't see yourself coming or going. All you need is a hole saw,a drill and bits, some tin snips, some cardboard for a template, an oval automotive K&N filter, flat metal stock, two bolts and the stock carb rubbers. Using the cardboard make a rectangular template of the carb inlets. Make sure the template is at least as large as your K&N filter. Cut two plates out of the sheet metal, but only cut the air holes in one size and the same size of the holes in the stock airbox. Drill two holes just big enough for the bolts to go through and then sandwich the K&N between the two plates and bolt it together. Install the airbox rubbers (I use a little silicone to make sure there is a good seal) and attach to the engine using the stock hose clamps.

[Terry in Australia]

That sounds like a pretty good piece of kit mate, I might try that on the weekend, do you have any pics of yours you can post? Cheers, Terry.

[Geeto67]

I'll try to dig it out this weekend and snap a pick. I patterned it after the old one piece air cleaners they used to sell in the 70's but those used stamped steel plates at the ends and either a foam, paper, or metal mesh filter. I shoved my two prototypes in the attic with the rickman when I moved shops a while back.

Honestly it can be made with a hacksaw and a portable drill with a hole saw in about an hour if someone is only marginally handy.

Basically you are making a K&N sandwich, the only important part is that you get a K&N that is big enough and tall enough to clear the velocity stacks inside. The way K&Ns are made the ends are rubber and act as a seal, all you need is enough metal to cover the open interior, but I have seen guys I showed how to make these extend it out and rivet/screw/weld on rain guards. You want the automotive type filters with the open top and bottom, the ones with the metal top and spigot bottom won't work for this. I'll see if I can find the part number of the one I used but you can take the measurements from the stock airbox and one carb rubber.

I always wondered if there would be a market for these, If I started making them how many do you think I would sell? The hard part is the filter as K&N isn't cheap. The first time I did this I took my measurments down to the auto parts store and dug through all the K&Ns they had on the shelf. That was about 10 years ago and I don't know if AP stores stock as much as they did in the early 2000s. But you don't have to use K&N, you can dig through the fram car filters too till you find one that works. I remember K&N also had these neat oval filters that could accomidate two carbs so instead of the individual pods you could have twin pods that use the velocity stack/carb rubber off the stock airbox.

[Terry in Australia]

Thanks Geety, that's giving me a few options, I better get off my butt and get out there and give it a go! I don't think I'll have any problems fabbing it up, providing that I can find the appropriate filter/s. Cheers, Terry.

[Retro Rocket]

Interested in those pics mate. I was considering doing a cut and shut with 2 airboxes and extending the bottom section so it has more volume,i was also going to increase the openings at the rear.......What do you think...

Mick

[Terry in Australia]

Well I think what Geety is saying is that with the sandwich airbox mod you don't need a larger airbox Mick, although that'll depend on the size of the air filter (or filters) that I can find. This will definitely be a "Low budget" job for me, because I'm sending Ken Piper another set of 32mm CV's to mod to suit the 836cc engine in my K1 so this is just a "quickie" job while I'm waiting on the CV's. Cheers, Terry.

[Retro Rocket]

Hi Terry, whats Ken charge for the carb mod? I need a set of carbs to run my engine in ...


Mick

[Terry in Australia]

Hi Terry, whats Ken charge for the carb mod? I need a set of carbs to run my engine in ...


Mick

I don't ask first Mick, I just pay..............  But he charged me 250 bucks to narrow the 33mm Mikuni smoothbores for my 1060cc engine, which I thought was very fair, he had a lot of work to do, I've seen plenty of 29mm Mikuni's on CB750's, but I've never seen 33's on one before? Cheers, Terry.

[Freaky1]

I think I'm going to do the air filter sandwich, I have been running UNI foam pods and they are nice but if I can do something to avoid cleaning and re oiling then I'LL DO IT! I'll have to find some nice stainless pieces to use, I have a real thing for making more work than I have too and I so love stainless! My original air box was trashed but the rubber v stacks are soft and in good shape so I think they will work.

[Terry in Australia]

Well I looked for a filter to use but couldn't find anything, and the prices for the K&N car filrters i saw were outrageious, so I went to plan B and reinstalled the OEM airbox, albeit with the 132.5's. Horrible, way too rich, wouldn't rev past 4000 RPM, and smelt way too rich. Back to my comment about the "choke effect" of the OEM airbox.

I came back, dropped the 132.5's out and fitted 120's, it'd rev cleanly enough up to 5000 RPM but just felt flat and lifeless, then it had a massive flat spot between 5000 and 7000 when I could pull on the throttle and it'd do virtually nothing, then from 7000 to 9000 it was like a 2 stroke power band, it just screamed!

Stuff it, next weekend I'm putting the pods and the 132.5's back in, they worked much better. It's only temporary anyway until I get the 32mm CV's on it, so not worth wasting any more time and money on. Cheers, Terry.