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Author Topic: Sheet metal airbox  (Read 458 times)

Offline 1fasgsxr

  • Posts: 1397
Sheet metal airbox
« on: Dec 08, 2017, 20:22:09 »
Anyone ever attempt to make an airbox from sheet metal of aluminum?   Thoughts?
http://www.dotheton.com/forum/index.php?topic=41083.0

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Offline J-Rod10

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Re: Sheet metal airbox
« Reply #1 on: Dec 08, 2017, 21:11:24 »
Couple companies make them.

So long as the internals are correct, and you're getting air in, I don't why it'd be an issue.

Offline 1fasgsxr

  • Posts: 1397
Re: Sheet metal airbox
« Reply #2 on: Dec 08, 2017, 21:57:24 »
Probably be easier to find a stock one but I don't know if it will even fit with the CR carbs installed.
http://www.dotheton.com/forum/index.php?topic=41083.0

I eat cake because it's some ones birthday somewhere...

Offline Maritime

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Re: Sheet metal airbox
« Reply #3 on: Dec 11, 2017, 16:47:31 »
There's a few folks on here who have made from both metals and a few from glass/carbon as well.  It's getting the volume right for the carbs that is key from what I've seen.
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Offline jpmobius

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Re: Sheet metal airbox
« Reply #4 on: Dec 11, 2017, 18:51:21 »
Seems to me there are 5 considerations. 1) You'd like to incorporate an air filter so your engine will have reasonable life.  2) You'd like to keep water out so if you get caught in the rain so your engine will keep running.  3) You'd like to separate your carb intakes from the wind - the so-called still air box.  4) You'd like to direct the air directly into the carbs bell mouth i.e velocity stack which would be good to incorporate inside the box.  5)  You'd like to design the volume so the resonant frequency of the air inside helps the engine tune. 

Since there is a lot to consider, I like fiberglass as a construction medium as it is a lot more flexible for the likely convoluted shape needed and is inherently airtight.  Also a lot lighter than most folks can manage out of metal (though I have seen some incredibly heavy fiberglass parts!) and much easier to alter.

Assuming this would be on your 400F.  The CR's should come with velocity stacks.  I would use them if possible.  I have CR's on my own 400F (sorry - airbox for it is project #872!).  I had to move the throttle bellcrank inboard of the left carb to not have it interfere with the tank hanging off the right.  PM me if you want the details - it was a fair bit of trouble but looks a lot better and the cable routing is far superior.
« Last Edit: Dec 11, 2017, 19:00:00 by jpmobius »
Mobius


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Offline 1fasgsxr

  • Posts: 1397
Re: Sheet metal airbox
« Reply #5 on: Dec 11, 2017, 21:54:07 »
I thought about making a fiberglass one from a buds stocker...just not sure on joining the 2 pieces back together. I would settle and run pods but I have never heard good stories of them working all that well.
I would love to see how you moved the throttle to the middle.
http://www.dotheton.com/forum/index.php?topic=41083.0

I eat cake because it's some ones birthday somewhere...

Offline 1fasgsxr

  • Posts: 1397
Re: Sheet metal airbox
« Reply #6 on: Dec 27, 2017, 13:32:49 »
I may be going forward with the fiberglass idea.  Thinking about making 2 half molds of the stock box from my buds 350 out of plaster and pour foam in the joined halves. From there lay the glass on the outside of the foam. My biggest issue is the Keihin CR's I am running are much bigger in diameter where the air box will connect so I cant use stock rubbers ... I just had to get these carbs... :(
http://www.dotheton.com/forum/index.php?topic=41083.0

I eat cake because it's some ones birthday somewhere...

Offline runmikeyrun

  • Posts: 390
Sheet metal airbox
« Reply #7 on: Jan 08, 2018, 01:38:32 »
I may be going forward with the fiberglass idea.  Thinking about making 2 half molds of the stock box from my buds 350 out of plaster and pour foam in the joined halves. From there lay the glass on the outside of the foam. My biggest issue is the Keihin CR's I am running are much bigger in diameter where the air box will connect so I cant use stock rubbers ... I just had to get these carbs...
Maybe you can mold a short (1/2” long ) stub of aluminum pipe into the box where your carbs are, and just connect them to the carbs with a short section of rubber/silicone tubing.  There’s a great hardware store by me and they have all kinds of tubing in different diameters.  A speed shop like Summit Racing night also have some, or even a radiator hose cut into sections would fit.


Here's where I list all my bikes:
'71 Kaw 250 Bison
'81 KZ750 cafe
'94 XR250L
2014 Yamaha Bolt

In progress: '68 CL350
END OF LINE.

Live to ride, Ride or die.

Past:
Rupp Minibike
Benelli Minibike
Tomos Moped (lol)
74 RD250
81 XT125
76 KH400
79 YZ250
77 RD400

Present:
14 Yamaha Bolt
81 KZ750E
94 XR250L
68 CL350 (in process)

Yeah, it's dangerous.  That's why I like it.