1976 KZ400d Airbox removal

I'm thinking of taking out the dirty old airbox from my '76 KZ400 in favor of two direct air pod filters right into the carbs. Can someone either talk me out of it or give me a rough step by step so I can get an idea of the work involved? Any feedback/wisdom/ideas/suggestions/ridicule is much appreciated. Thanks.

Edit: I should state that the compression is excellent on my bike, it runs and starts like a dream and the carbs have been cleaned but will soon be professionally rebuilt to make sure their tuned right and all the gaskets replaced. I've found the pod filters cheap, as well.

Hi Mjsenz
Welcome to the site.
I am not anti pod and have used pods myself but have seen a number of posts here which say that with the kz400 it is very difficult to get the 400 to run right after fitting pods. Stick around as I am sure someone with experience will be along soon.

Replacement air filter seems to be available from Z1 Enterprises www.z1enterprises.com/detail.aspx?ID=1606

and old plastic or rubber airboxes can be cleaned up to look good. If you do go to pods you will probably have to rejet the carbs.

good luck.


PS www.kz400.com has a lot of great information

Yes, very true, the KZ400's are tricky carbs and require a lot of patience and testing to get them jetted for pods. But it's not impossible.

Also, from what I've seen, the piston slide CV carbs are easier (and cheaper) to deal with than the later diaphragm CV carbs.

A few tips, though, before you start.

Make sure the pistons move up and down in unison, with no resistance. Put a drop of oil on the rings of the piston slide and other rubbing areas. The critical thing to getting the slide to move freely is cleanliness (polish if need be) and upper cap alignment.

Make sure the slide piston bores are not deformed, dented, etc. Then make sure they are smooth. Use 1000 or 2000 grit if they are rough. Then while installing the upper caps on the carbs, put the carbs in their normal alignment, and reach in and slide the pistons up and down as you slowly tighten the two screws on the caps. If it binds, start over. When you are done, you should be able to tip the carbs forward and back and both slides should top out and bottom out at the same time.

Notice how the top of the carb caps are plastic? That is there so you can identify when the slides are all the way up while running. When the slides top out, the plastic will appear to have a dark ring shape on it. Check it out when you pull the acarbs so you can identify when the slides are topped out. Normally they should be topped out solid anywhere above about 1/4 to 1/2 throttle.

Another major issue with those carbs are the orings on the main jets. They must seal perfectly or you will never get consistent jetting.

Another thing, they may require a rubber plug to seal the inlet to the pilot jets.

At the top of the carbs, under a cashew-shaped metal plate under the upper cap and piston, are two air jets. They may also require adjustment to get it to run right.

Here is a diagram for the main jet orings:

Most importantly: Do not throw away the airbox.