Topic: 1972 CB 750 airbox

[beemerbum]

When taking apart my airbox, I noted that the "separator" Part 17213-300-000, according to diagrams, where it is shown as a separate part of the airbox, seems to be fixed in place and non-removable. The diagrams I'm looking at also show a rubber gasket surrounding the edge of the "separator. My '72 airbox has none of that. Did the PO possibly glue the "separator" into the box? Was there a change in the airbox?  The gasket is available form DSS as part 17221-341-000 on special order.

[69cb750]

The separator is retained by two screws and nuts, there is a gasket

[StockRider]

The gasket is often missing and the PO probably didn't glue pieces together..., the carbs did. The combination of fuel vapors, heat, and paint turns into a fairly strong glue.

I spent several hours with a set of Exacto knives and a heat gun to get my cracked K0 box apart, without cracking it further. Other than the ribs I don't think the '72 is constructed much differently.

[beemerbum]

That explains it. Thank you gentlemen

[Johnie]

I wonder how necessary that gasket is? I see so many airboxes come through without it.

[beemerbum]

Very good question. My K1 CB 750 has no gasket in the airbox and runs very well. If the separator is sealed via silicone or other material, isn't the purpose accomplished? What's magic about the airbox "packing" as the DSS site refers to it?

[ekpent]

  Sure a good seal would help keep water out. Not having a tight seal between the top and bottom and an air leak there may mimic a little bit a popular mod back in the day where so many holes of a particular size were drilled in the bottom I think. Sure Hondaman is familiar with the mod though not sure he uses it in his book. May have to take a peek.
  Most all of my air boxes seem to still have them but they are old and want to pop out sometimes and they hate getting gas or heavy fumes on them from a overflowing carb.  Swell up and get mushy.