Topic: Breadbox Airbox Source?

[jamanred]

I've been able to find all the answers to my questions from these forum threads until now.  Awesome site!!

(73 CB500 K2)

I've seen breadbox air boxes on some custom bikes.  Anyone know where to source something like that?  I've had no success in searching the last 6 months.  Any thoughts on fabrications or the reuse of any object and base air filter to use?

- Velocity stacks look great, but I don't find them very practical for daily riders (why open up the carbs to debris? unless it is a show bike)..
- POD's seem to work well, but setting the jets are a pain (been reading this from everyone) and would produce an unfriendly droning sound
- Air box (not that I have a complete one) with no side covers (and with electrics relocated) looks like the bike just got robbed..  Already committed to abandon stock..

[bollingball]

You will probably have to be committed. I never thought pods seem to work well.
 There was a guy making them a member here. Look for Antipod
I think you will still have some jetting to do.

                                              Ken

[70CB750]

Check my build - I replaced pods with car filter, some aluminum and chunks of radiator hose.  Or search forums for sandwich. 

[Deltarider]

73 CB500 K3? K3?

[jamanred]

Thanks for the catch..  It's a K2.. 

[jamanred]

Check my build - I replaced pods with car filter, some aluminum and chunks of radiator hose.  Or search forums for sandwich.

What yr make/model vehicle did you use for the air filter?  the thread on sandwich is exactly what I was thinking.  I saw that some felt velocity stack would help internally though.  How has your bike been riding with out them?

[70CB750]

I can give you the purolator number, I should write it down anyway. It was one of those round filters I was able to bend into oblong shape. Will get back to you.

[jamanred]

Awesome!!  Thanks!!  That would give me a starting point.  Having the filter in hand, I can throw the basic design out to my metal guy and see what he can come up with. 

[70CB750]

Purolator A30045. Pep boys have it or you can find it online.

[Retro Rocket]

If you can incorporate the stock velocity stacks it will always work better.....

[jamanred]

Holy crap is there a ton of info on the use of pods here.  Obviously I did not due enough research on this (really thought I covered my bases, but was reading up on track bikes, so that is probably where I errored).

Fortunately, I do have the stock velocity stacks from the old box (broken with missing gaskets and lid) and they look to be in good order.  I think I will be working toward the sandwich design, with existing velocity stacks and borrowing heavily from 70CB750's design.  Being a lite rider, I've never riden in the rain, so the open filter design will be a challenge to work with.

Picking up a complete and non damaged airbox seems like the best thing to do, but I've already removed everything to open up the triangle space (tabs included).  I guess I will be making a cosmetically pleasing box to accommodate the open space.  I will keep everyone posted with progress and pics..

[Rgconner]

Here is another option.

Sort of a cross between breadbox and stacks.... the Antipod!

http://forums.sohc4.net/index.php?topic=79491.0

[DYSKORD]

Antipods are a good solution.

But I think this is what your looking for http://www.steeldragonperformance.com/air_boxes_7.html

[jamanred]

Both look fantastic and would do the trick, however, I have a 500.  The air box is for a 750 and the antipod is 550/750.  Not sure if my carbs will line up..  If they do, I will definitely order one of these..  Why recreate the wheel when there is one online..

[Rgconner]

I bet they are the same, the 500 and the 550. Not much difference topside, but the gearbox is different.

This guy:

http://forums.sohc4.net/index.php?topic=100975.0

has em side by side. Maybe he can confirm or deny the spacing?

[DYSKORD]

Both look fantastic and would do the trick, however, I have a 500.  The air box is for a 750 and the antipod is 550/750.  Not sure if my carbs will line up..  If they do, I will definitely order one of these..  Why recreate the wheel when there is one online..

Call'em, its a father and son duo I believe. Nice guys. They could tell you pretty quickly if they could or not. Worth a shot I guess.

[Retro Rocket]

Antipods are a good solution.

But I think this is what your looking for http://www.steeldragonperformance.com/air_boxes_7.html

The antipod will flow up to 300HP and is designed by a company that builds induction systems for formula one teams, it will work better than the bread box design and will flow more, i suppose it all depends on what you want. Most breadbox filters actually restrict flow, this has been documented here and there is a guy here that is modifying a breadbox to flow more, if i can find it i will post a link....

[jamanred]

The steeldragonperformance model, provided it will fit, doesn't look like it has stack built in or a bolt on way to add.  Thinking it will create the same issues as POD's.  But like the price point.

The antipod's look like the real deal, but +$200 is a tad steep for me, again..provided they will fit, but will verify the dimensions.

Back to the "breadbox"..  Since I haven't found any articles other than 70CB750's, the link you are referring to is definitely something I need to read.  I guess from a noob's perspective, the stock airbox has a single inlet with a small diameter.  If I were using the stock stacks and increasing the air flow with a somewhat 360 degree radius of airflow via an exposed filter (like the puralator model 70CB750 is using), am I really adding a choke point for air flow?  I mean for a stock 34 hp motor, wouldn't this still be a modest upgrade and not a restriction?  Obviously re-tuning the carbs (and not forgetting the timing..?) would still something to not leave out.

[Rookster]

There's a few things to consider besides just increasing the amount of air available.  The stock boxes create a large volume of basically flowing air in one direction.  That air is free to flow into the carbs and directed by the stacks/shape of the airbox and the airbox inlets.  When you take away that volume of dedicated air and replace it with swirling and flowing air you get interference.  The stacks are pulling air into the carbs throats that was moving a different direction fractions of a second ago.  This explanantion isn't technical as I don't know anything about flow dynamics but it explains why more air isn't really better air.  The stock box on the other hand is created to allow air to flow directly into the stacks.  There's no swirling or crosswinds.

You then have to consider the shape and volume of the breadbox.  The breadbox looks great but it is really small compared to a stock airbox.  If you fit stock stacks you end up with a huge restriction becuase the stacks are too close to the back of the box.  You are basically forcing the air to flow into the breadbox then stop and turn 90 degrees into the stack.  Sure more air is available but it isn't flowing as smoothly or as fast.  The reason the antipod works is becuase the air isn't restricted by a box.  The antipod is basically velocity stacks with a filter on the back.

The final restriction comes from the stock cylinder heads which are designed to flow with the stock airbox.  If you don't port you don't really gain anything by increasing the potential volume of combustible air with pods or a breadbox.  Instead you create a condition that forces you to re-tune the carbs to run the same as it would with the stock box.

None of this is very techinical and I'm sure it will be corrected.  I wanted to use a breadbox as it looks great.  I tried all kinds of combinations (CB750) and still always had a huge flat spot when I cranked open the throttle.  I put the stock box back on and there was no flat spot.  For me it just wasn't worth the effort.

Here's a great article about setting up a breadbox for the CB750.  You can see that more air isn't always better by this mod.  http://www.lowridersbysummers.com/twt/13/index.html  This guy has been building CB750s since the 70s and is as professional as they come.

Scott

[jamanred]

There's a few things to consider besides just increasing the amount of air available.  The stock boxes create a large volume of basically flowing air in one direction.  That air is free to flow into the carbs and directed by the stacks/shape of the airbox and the airbox inlets.  When you take away that volume of dedicated air and replace it with swirling and flowing air you get interference.  The stacks are pulling air into the carbs throats that was moving a different direction fractions of a second ago.  This explanantion isn't technical as I don't know anything about flow dynamics but it explains why more air isn't really better air.  The stock box on the other hand is created to allow air to flow directly into the stacks.  There's no swirling or crosswinds.

You then have to consider the shape and volume of the breadbox.  The breadbox looks great but it is really small compared to a stock airbox.  If you fit stock stacks you end up with a huge restriction becuase the stacks are too close to the back of the box.  You are basically forcing the air to flow into the breadbox then stop and turn 90 degrees into the stack.  Sure more air is available but it isn't flowing as smoothly or as fast.  The reason the antipod works is becuase the air isn't restricted by a box.  The antipod is basically velocity stacks with a filter on the back.

The final restriction comes from the stock cylinder heads which are designed to flow with the stock airbox.  If you don't port you don't really gain anything by increasing the potential volume of combustible air with pods or a breadbox.  Instead you create a condition that forces you to re-tune the carbs to run the same as it would with the stock box.

None of this is very techinical and I'm sure it will be corrected.  I wanted to use a breadbox as it looks great.  I tried all kinds of combinations (CB750) and still always had a huge flat spot when I cranked open the throttle.  I put the stock box back on and there was no flat spot.  For me it just wasn't worth the effort.

Here's a great article about setting up a breadbox for the CB750.  You can see that more air isn't always better by this mod.  http://www.lowridersbysummers.com/twt/13/index.html  This guy has been building CB750s since the 70s and is as professional as they come.

Scott

That is some good info to consider.  Thanks

[Scott S]

 That is a good link. I just picked up one for my CB500 because A) it was stupid cheap and, B) I don't have all the air box parts for this project. (I'm doing a "sweep the floor" bike using leftovers from other projects.)

 It appears that I have the thinner KZ version. How hard would it be to fab up some wider metal to make it the thicker version so I could use the stock velocity stacks inside?
 Or, I wonder if there's a car filter of some sorts that I could use with longer bolts to just get rid of the metal middle piece all together?

[lucky]

You will probably have to be committed. I never thought pods seem to work well.
 There was a guy making them a member here. Look for Antipod
I think you will still have some jetting to do.

                                              Ken

The reason many owners cannot get pods to work properly is that they are not willing to take the carbs off and rejet. End of story.

And main jets won't do it alone.

[Retro Rocket]

The reason many owners cannot get pods to work properly is that they are not willing to take the carbs off and rejet. End of story.

Its not that simple, most pods do not have velocity stacks so the carbs are getting turbulent air instead of a smooth direct flow that the well designed stock velocity stacks deliver. The Honda carbs were designed to be used efficiently with the stacks, if you search the forum you will find plenty of threads that offer a thorough explanation of the process. There are a growing number of members that , originally were adamant that the pods were a good approach but have now gone back to the stock set up and found it extremely easy to tune when compared to pods.