Author Topic: Breadbox Modifications  (Read 837 times)

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Offline Dolomite

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Breadbox Modifications
« on: April 08, 2019, 03:36:42 PM »
I was finally fortunate enough to come across an original breadbox intake thanks to a kind CL seller remembering my interest.

One of the main modifications I've read about is blocking off the sides of the breadbox internally to prevent the dreaded crossflow.

I have also been looking at the K&N rectangular filters and am trying to determine if one of them would fit comfortably inside the top and bottom covers of the box without the screens. Headspace between the stock intake stack and the filter may be a concern here. If anyone has done this already, I'd love to hear your thoughts.

Any other modifications anyones done I'd love to hear your input. Thanks!

Offline evanphi

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Re: Breadbox Modifications
« Reply #1 on: April 09, 2019, 10:12:16 AM »
Hey! Who turned out the lights?


You could always ask K&N about the fitment. I bet they've seen it before too.
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline seanbarney41

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Re: Breadbox Modifications
« Reply #2 on: April 09, 2019, 07:51:29 PM »
I have run HA style breadboxes on a couple different cb750f's.  I wouldn't worry about blocking off the sides.  I have not experienced any problems with crosswinds affecting performance. 

A couple more tips...fit the stock air box boots to your breadbox and you will have an easy time tuning...as these are velocity stacks designed specifically for the flow needs of your engine.  Also, I use UNI foam filter material that comes in a sheet and cut it to fit the breadbox.

Also, be aware that these breadboxes were available in at least a few different overall sizes...use the biggest volume one you can find and fits for best performance.
If it works good, it looks good...

Offline Dolomite

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Re: Breadbox Modifications
« Reply #3 on: April 10, 2019, 06:43:24 AM »
I'm still waiting for it to arrive so I haven't had hands on it yet. Its the style with the perforated screen rather than mesh. I've attached a photo.