Topic: K&N air filter - stock airbox - jetting differences ?

[greenjeans]

Yes I've searched .  Finding mostly answers dealing with pod filters.

75 CB750K  (back from a 15 yr hiatus)   stock 4 into 4 exhaust.  Stock airbox.

About to order a ton of carb parts & was thinking of adding a K&N filter as I can find those for just a bit more than the stock Honda filter.

K&N's site claims that no changes in stock jetting are necessary.  Seem like I remember reading something to the contrary.   Can't remember if it's for pods or a "stock style" filter.

Anybody know for sure before I order new jets ?

[Old Scrambler]

My K3 came with 105 mains...........I switched to 120s and a K&N filter in my stock box with 4 1/4-inch extra holes drilled into the bottom.  Now run stock exhaust with caps.........seems to be just fine.

[dhall57]

Hey greenjeans, The PO of my 750K6 put a Mac 4 to 1 on it. Im sure when this was done the jets had to be changed to work with the  Mac set up instead of the factory pipes. My A/F box is all stock. I have no idea what size jets mine are, but I recently replaced my stock air filter with a K&N and have not changed anything. The bike honestly seem to run and breath a little better. The K&N was for sure worth the extra money.

[KeithB]

I have a '72 750K and replaced the air filter with a KN and kept the stock jets.
No problem.
I do think the '72 ran a bit rich anyway....

[TwoTired]

These days, you have to ask if ethanol is involved.

The K&N reduces the carb throat vacuum slightly. (Makes it slightly leaner.)
Gasohol also make the ratio leaner.  Less energy in alcohol/per unit volume.
A more open exhaust will improve scavenging so a more air and fuel are needed.

Depending if starting from stock configuration, no changes are needed for the K&N.  Add some other things, maybe so.

Cheers,

[greenjeans]

Just what I needed.  Thanks, fellas.