k&n filter bags

Someone is going to find this info useful..

I spent 4 hours today riding in shitty shitty rain, from State College (Penn State) coming back to Philly.
Pretty much torrential down-poured the entire way.

My 79 cb650 has velocity stacks on it which means I should not be able to ride in rain at all.

So… how’d I do it? How’d I make it home?

My bike should’ve bogged down and sucked in a shit ton of water and cut-out and left my stranded…

First, what are velocity stacks?

They are usually metal cones that go in place of where your air filter, or pod filter would be. It goes from a large diameter to a smaller diameter, which helps speed up the airflow going into your carb, which makes more power. Essentially it’s the Venturi effect. Big to small will increase speed/pressure. (or something like that. I’m not a scientist.)

Long story short velocity stacks make the most power compared to pretty much anything else. Def more power than pods, by a long shot. So increase your jets a couple sizes…
Anyway… there is no filter element at all. Nothing except maybe a screen to keep dirt, and bugs out. So… when it rains, you’re fucked.

The solution:

A few years ago I came across these (rc-1820dk):
K&N Filter Bags

They keep 100% of the water out and let all the air in.
Pretty rad.

So, I’m sure someone right now is thinking… “uh, I have pod filters and I ride in the rain all the time with no problems…”
Yea, well… my response would be that riding around Philly for 20 mins in the rain is a hell of a lot different than riding 4 hours in a down-pour… Not silly dumb rain… I’m talking about shitty down-pour. Rain will drench your pod, It will get in every crevice, and it will be so dense with moisture that the bike straight up will not run. And you’re fucked. Adam and I have learned the hard way.

Do yourself a favor and pick up these bags if you do any long distance riding in the rain and you have pods.
Or… get some velocity stacks and make some real power, just keep the bags under your seat or something… just in case it rains. That’s what I used to do. But I ride everyday rain or shine, so I just keep the bags on always now.

…Just my input. I wish I knew this info 4 years ago.
Would’ve saved some hours sitting around waiting for the pods to dry out.

Or, be boring/safe and leave your cycle stock/slow. ha

15 responses to “k&n filter bags”

  1. Adam says:

    Saved me in Arkansas during a torrential down pour. I think they look crappy but you can’t beat the function. I think they were designed for water crafts and off road stuff.

  2. Tom says:

    I cant vouch for the bags, but I can vouch for being caught riding in heavy rain for a few hours in the poconos a few years back on the 500 with pods and that was pretty rough. The bike was barely running on maybe only 2 cylinders and was maxing out at around 50mph with full throttle. Once i got to the next town and had to slow down, the bike died and had to wait until everything dried out. Would have loved to have know about these things then.

  3. Adam says:

    @Tom what pod filters were you running?

  4. Tom says:

    I have K&N filters on that bike. I was not 100% sure that was the reason for the bike to be running so rough. But I can say that once the rain stopped and i was able to dry everything out, the bike ran fine over the next 5 days through the Adirondacks and northern New England before making it back to Philly.

  5. Morgan says:

    Hi Guys,

    Question – Can I and would it be worthwhile to fit velocity stacks to a 1974 cb 200?


  6. ludwig says:

    make sure that you oil your pods properly, otherwise you might as well run open carbs.

  7. Jason says:

    Sounds like Ludwig is someone who builds motors . . . and anyone who does will tell you not to run stacks. . . unless they’re trying to drum up business. They offer little benefit except in all-out drag racing and the detriments should be obvious. Ever see how clean and precisely finished the internal surfaces of a motor are? How about after sucking in dirt, sand, dust and what-else. Bad news.

  8. ed says:

    I get what you guys are saying. Real engineers designed the stock airbox system the way they did for a good reason. Diverting from it will only lead to problems at some point, some day .

    However… pods and velocity stacks are fucking cool. I guess I’m willing to risk reliability and longevity for the sake of messing with stuff because that’s what interests me.

    I’m not recommending people do what I do… but If you do wanna run pods or v-stacks, which, a ton of people I know do… the k&n bags at least help.

    I’ve read on forums oiling pod filters can be negative because the oil can (overtime) get sucked into the carbs and clog jets and gum them up, so I’ve never oiled pods before.

    I understand your point and clearly I won’t dispute you know a million times more than I do, but I’ve been running the velocity stacks for a couple years now and have had no problems (that I can tell).
    For everyday riding, it seems that always using the k&n bags overtop the v-stacks eliminates most dirt etc getting inside, yet you reap the benefits of (what seems to be) faster, more dense air intake.
    When going from pod filters to velocity stacks I increased my main jet and noticed a significant increase in power / throttle response.

    But yes, if you wanna be a safe, betting man. Leave your bike stock.

  9. Jason says:

    Damn, Ed. So now I’m just a milquetoast stock-is-safe type of guy? My feelings are sore.

    Yes, stacks and pods are cool. The former are really more for show bikes and drag bikes than those that are seeing frequent street duty. Pods are the perfect compromise. Much better airflow while still protecting your expensive investment (or preventing a future expensive investment) in precisely built motor.

    FWIW, I modify the shit out of most of my bikes for performance reasons. I just try to hide it when I can ;-0

    And I run K&N’s on all of them. Redoing motors is a pain the ass.


  10. ed says:

    ha… you know I didn’t mean it like that.
    I appreciate your input. I really do.
    I ran pods on the 650, and for whatever reason, the 650 runs best with v-stacks, so I keep it that way and always run the k&n bags.

  11. ludwig says:

    all pod filters should be oiled. k&n typically come pre-oiled, but not in all cases. a little bit of oil won’t hurt your carbs. just do a 50% gas/oil mix and let it dry, no big deal and it catches all that dirt and dust.

  12. Nick says:

    As long as you use the kn oil for the filter and not over do it. You will never have an issue with it getting sucked into your carbs.

  13. […] Better than pod filters are velocity stacks. Bike runs best with these. They’re a little hard to find though. You want 43-46mm. But… you’ll want to run k&n filter bags. Info HERE. […]

  14. mike says:

    hey thanks for this info it’s been real useful.
    i have a 79 cb650. took off the stock airbox and switched to pods. bike ran real lean so i took it to a guy who cleaned, rejetted and synced the carbs. he did not drill out the pilots though. bike has a better top end but still bogs out in low rpms.

    V-stacks would make that worse right? is there a 1 into 4 solution or should i just put that ugly plastic piece of stock filter back on?

    thanks for your help

  15. ed says:

    based on what you said… you need to increase your slow jet.
    yes. v-stacks would make it worse.
    keep the pods. the stock air box sucks. no, there isn’t a 4-1 solution.

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From Past

Published - Jul 3, 2013

Philly to Denver – Route

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