Yes. I have a '78 550k and had to buy a stock air filter. The bike didn't have any air filter when I bought it in July. The best price I found was through Dennis Kirk. The filter was about $29 and shipping was another $5 or $6. My Harley neighbor turned me onto this company when he received a Dennis Kirk catalogue for metric bikes. They have many good parts - 4 into 1 exhausts, oil filters, plugs, etc. You should be able to find this company online via google.