Air filter pods

If it's broken or just needs tweaked

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coreyr6624
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Joined: Thu Dec 17, 2015 7:29 pm

Air filter pods

Postby coreyr6624 » Fri Jan 08, 2016 12:23 pm

I'd like to replace the original air cleaner on my 81CB650 does anyone know if it will affect the way the bike runs? Will it require tuning? Also if anyone knows what size do the pods need to be? I see they are rated in metric sizes, 54mm, 62mm, 49mm and so on.

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Folsoml
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Re: Air filter pods

Postby Folsoml » Fri Jan 08, 2016 4:13 pm

Your bike year model should have CV carbs, and these do not work well with pods. Mainerider provided what I consider to be the best explanation of why pods are troublesome:

Mainerider wrote:
Folsoml wrote:Let me see if I understand the problem with pod filters. The stock carbs are tuned/jetted to allow a perfect mixture of fuel and air if the bike is fitted with the standard airbox filter system. When a person adds pod filters, they allow too much air for the standard jets, requiring the carbs to have larger jets installed to get the correct ratio.

I'm sure someone will correct me if I am misunderstanding what is going on here, so I'll get to my question: Since pod filters are so popular for people who want that cafe racer look, has any company ever tried to make a pod filter that mimics the air flow of the air box, thereby allowing them to be used without a rejet?



An airbox serves many purposes and one of the most mportant is to supply the carbs with a consistent and steady reserve of STILL air. Under most conditions, pod filters can't offer this; they are affected by turbulence from several sources, including cross winds, the rider's body, and the bike itself . Air pressure is directly related to air speed and carbs have a hard time dealing with the constantly varying vacuum pressures that pods often cause. This varying air speed problem occurs on even a single-cylinder bike; the problem only increases on multi-cylinder bikes. Each pod is essentially its own air supply system; with potentially varying air speeds (hence varying vacuum pressure); at each pod (due to varying turbulence levels), you will have an issue that mimics that which occurs when one or more of your carb intakes has a vacuum leak: erratic idling, stumbling, surging, etc.

This is one of the reasons that a lot of pod-equipped bikes suffer from surging problems; even after re-jetting, the lack of consistent vaccum pressure causes fuel flow to ebb and flow.

We haven't even touched on the problems of pods while riding in rainy weather...

In summary, in certain situations pods can be beneficial but overall, for street riding, they cause more problems than they cure. Pods look cool, they make carb removal and install much easier, but they are inferior to a well-designed air box. The manufacturers in the 70s and 80s weren't stupid, their marketing departments knew even back then that people loved the look of pods and if they could have fitted the bikes with pods without adversely affecting performance and ridability, they would have; they didn't because an airbox serves several important roles that pods can never handle.
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cb650
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Re: Air filter pods

Postby cb650 » Fri Jan 08, 2016 5:19 pm

I have had 2 CV carbed bikes bikes running pods very well. But never could get my 80 with mechanical carbs to work well. Especially with interference from the choke. But many 750 and 550 have them.
With the cv I learned to make the vent tubes short and cap them with a filter.
Did you clean the tank out?!?!?!?!

coreyr6624
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Joined: Thu Dec 17, 2015 7:29 pm

Re: Air filter pods

Postby coreyr6624 » Sat Jan 09, 2016 6:59 am

Thanks

MEHall
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Re: Air filter pods

Postby MEHall » Mon Jan 11, 2016 10:21 am

Although it looks well to use a pod filter and CV carbs are more forgiving it's in fact not good to use them! I'll clarify, when you mount a pod filter there will be turbulence so you need to mount bigger jets, and that makes worse mileage! The best thing is in fact to use the stock airbox. :wink: But if your airbox is broken i got the idea that you make an airbox and mount podfilters on it! :wink: The design of the airbox is completely up to you. :wink:
I hope this will help?





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Riding bikes? I ride where ever i want and whenever i want. :wink:

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Murphy C
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Re: Air filter pods

Postby Murphy C » Mon Mar 14, 2016 12:36 pm

I'm not sure what pod filters your using bit I use Uni pod filters and I have no need to reject. I use the uni stage 2 filter. The problem with open air flow pods like velocity stacks is the need for reject and retuning these uni basically mimic the air flow the original airbox has. I've used these on my cb400,900f and 750 and now on my 650. I live at sea level try em.

juntjoo
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Re: Air filter pods

Postby juntjoo » Thu Dec 06, 2018 3:39 am

cb650 wrote:...
With the cv I learned to make the vent tubes short and cap them with a filter.



Short? As in just enough to reach them from outside(as they're connected inside/in between the carbs)? And how do you cap them with a filter? Is this a makeshift mod or are there parts for this? Thanks
82" cb650 Nighthawk

juntjoo
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Re: Air filter pods

Postby juntjoo » Thu Dec 06, 2018 3:45 am

Murphy C wrote:I'm not sure what pod filters your using bit I use Uni pod filters and I have no need to reject. I use the uni stage 2 filter. The problem with open air flow pods like velocity stacks is the need for reject and retuning these uni basically mimic the air flow the original airbox has. I've used these on my cb400,900f and 750 and now on my 650. I live at sea level try em.


I checked em out and they look like standard pod filters, which, at least with my nighthawk 650 won't fit on carbs 1 & 4 as they have only about 52mm room between them and the bike frame. You didn't have this problem? I'm considering the K&N ones, the two pods that fit onto two carbs a piece. They have a flatter profile and I read in a review they barely fit but did on my bike. I'm guessing my model is particularly restrictive for fitting pods.
82" cb650 Nighthawk

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Re: Air filter pods

Postby cb650 » Thu Dec 06, 2018 5:10 am

UNI filters are flexible. dont last as long as kn but dont cost as much either
Did you clean the tank out?!?!?!?!

juntjoo
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Re: Air filter pods

Postby juntjoo » Thu Dec 06, 2018 5:14 am

cb650 wrote:UNI filters are flexible. dont last as long as kn but dont cost as much either



Thanks. Good to know. Found some K&N ones, the two on two set for $50 barely used. Might take them if I can verify they fit okay. Uni's aren't that cheap. Like $15 a piece
82" cb650 Nighthawk


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