I just switched out my Rotax-brand plugs at 200 hours. I run strictly mogas but 400 hours seemed like pushing it. Changed to the standard auto plugs. The connectors fit fine. Just don't mix and match Rotax and NGK plugs; it's all or none.
RV4-->6-->6A, (built by Villanueva, Tolle, and Mosher)
AirCam finished and flying!
RV-14A under construction.
Cameron Park, CA (O61)