The California Air Resources Board has issued an executive order certifying a 2018 Kawasaki Ninja 400 with a 399cc engine. The certification confirms what we assumed earlier this year after a local television news program aired a story about Kawasaki filming a commercial in Milwaukee, revealing the Ninja 400 name.

Related: Oops! Milwaukee News Crew Outs 2018 Kawasaki Ninja 400

Since that story broke, Kawasaki announced most of its returning 2018 U.S. models, which noticeably omitted the Ninja 300. We can now safely assume that the new Ninja 400 will be replacing the 300 in Kawasaki’s lineup as its entry-level sportbike.

The new Ninja 400 continues a trend of beginner bikes growing larger and larger in recent years. The 249cc Ninja 250 had been around for years, and you can still regularly find them on the used bike market long after it was replaced in 2013 by the Ninja 300. The impetus for that displacement increase was the introduction of a new rival in the Honda CBR250R. Since then, the Ninjette has seen more new rivals sporting even larger engines in the KTM RC390 and the Yamaha YZF-R3. Honda’s CBR250R was later replaced by the CBR300R (and hopefully soon, a larger version of the new CBR250RR currently offered in Asia). It’s also likely just a matter of time before BMW puts its G310 motor in a fairing. Apart from the late-to-the-party Suzuki GSX-250R and offerings from smaller manufacturers like Hyosung, the entry-level sportbike market has long outgrown the quarter-liter displacement that thousands of new riders started out on for years.

While the CARB certification confirms the engine displaces 399cc, the document does not tell us how it reaches that size. Kawasaki had previously produced a Ninja 400 in Asia (and briefly, Canada) that was essentially a smaller version of the Ninja 650’s powerplant but it’s more likely we’re looking at either a sized-up version of the Ninja 300’s engine, if not a new motor all-together.

To keep costs manageable for the beginner market, Kawasaki is likely keeping its littlest Ninja a Twin, so those hoping to see a small-displacement Inline-Four will have to keep dreaming. Increasing the 300 engine’s bore from 62.0 mm to 72.0 mm while keeping the stroke at 49.0 mm will produce a 399cc engine, but a more moderate increase in piston size combined with a longer stroke may be more likely.

With a 399cc displacement, the 2018 Kawasaki Ninja 400 qualifies for Japan’s sub-400cc license class, so it’s possible we’ll see it next week at the Tokyo Motor Show. It’s more likely, however, that Kawasaki will wait for EICMA next month. As always, Motorcycle.com will have the latest information as it becomes available.