A Modern Air Filter Replacement Alternative

For those of us with the stock KZ750 Twin air box, finding air filter replacements can be a hassle.  Here’s a new solution!  First, let’s look at the common options we face:

  • Foam Filters – Less restrictive (a jetting consideration), and need to be oiled to maintain usability… but available at many stores.
  • OEM/NOS Filters – Some are still out there on eBay (Air Cleaner Element 11013-051), and still a good choice if you can find them, but the foam rings will likely be disintegrated, and the NOS filter will likely cost more than it’s worth.
  • Your Old Filter – Yes, you blow it out with the air hose, and it looks fine… kinda’… okay, maybe not.
  • Pods – Yep, you’ve had enough and you swear that some day soon you’re gonna tear out the stock box and go with pods.  If so, this article isn’t for you.

…so the other day, I said to myself, “…man, there’s *got* to be an alternative out there”, and I started searching deep on the Internet.  Crazy enough, my search led me right back here to my own site!  It looks like “Paul Nolz” posted a simple message about the Fram CA-9248 right under my nose way back in 2011 about an alternative that I somehow missed until now.  Argh!

Was it too good to be true?  I looked it up, and for around $20, they were still available on Amazon, so I ordered one:

Comparing them, they are almost the same in nature, with a few small, important differences…

First, the Fram is sealed on one end, where the OEM is not.

Second, the Fram is also just a millimeter or two longer, due to a “lip” at the open end.

Third, the open end is definitely a bit smaller on the Fram, and will be tight around the air inlet tube.

But since there is that one small hole in the bottom of the air box that exits to the outside at the bottom (drainage? second inlet? not sure why), I think I’ll go ahead and cut open the bottom of the filter…

And like Paul wrote in his post, it is a bit snug on the tube, but not too much.  But the flare at the top of the tube makes it an even tighter fit.

So, just like Paul’s brother did, I applied a little WD-40 and it slipped right on.

Then, in she goes, only a *tad* more sung than the stock filter.
The only odd thing is that you can’t really feel when the filter is seated in cradle at the bottom, since it’s made out of foam.  But then, you can pretty much only get it installed the right way anyway, or it won’t close, so that’s good.

So thanks again to Paul (and his brother), 12 years later as I write this, for having solved my problem (and maybe yours) with the Fram CA-9248 way back then.  Much appreciated!


  1. Dustinsandwich

    Hey there, anyone reading this. I hope you can help me, I’m flummoxed.

    I just bought a 1980 KZ750G1 in great shape with a sidecar. Everything is good, except the previous owner had replaced the airbox with pods and failed to rejet the carbs. Being of sensible mind on this, I sourced a replacement airbox, filter, and boots.

    My problem is that I can’t for the life of me figure out how to get it in the bike! I’ve removed the carbs, the carb manifolds, the emissions vent bowl thing, the battery box, side covers, and even the wiring harness loom on the left side.

    Is there a trick I’m missing? It’s not described in the factory service manual and I can’t find any posts about it. The only thing I can think to try next is to remove the rear wheel and mudguard and maneuver it in from the rear. Is this the solution?

    Thanks for your help

  2. Biquetoast (Post author)

    Sorry, I don’t know, mine have the stock boxes in them and I’ve never had to try to remove or install one. I was dubious about it not being in the service manual… until I looked, and yeah, nothing. However, I did find a partial mention of it in the service manual for the ’79-’84 models… in there, they instruct you how to lift it out of the way with “some sort of cord” as they put it, so as to not hinder when removing the engine. So… I assume it would come out through the engine area, but I don’t even know that for sure. On page 70 there’s a disassembly flowchart that has in order: Motorcycle->Battery->(left side cover, turn signal relay)->Battery Housing->Air Cleaner Housing. And then three pages later (73), the part about unbolting it all just to move it but not remove it. THen later, after engine re-installation, they just mention that you have to install it an tighten two bolts. They don’t say it, but I’m guessing in the mind of the author, it was hanging inside the chassis the whole time. So…. I know that doesn’t help, but if it can’t come out the side or the top, you might have to remove the engine to get it in. Hey, how about dropping a line to the person you got it from to ask how they got it *out*…? 😉 Good luck man….

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