Kawasaki has been spotted testing a new KX450F race bike in Japan, suggesting big changes are on the way for 2019. The updates include new bodywork, electric start and, most notably, a brand new engine.

To prepare for the 2018 All-Japan Motocross season, Kawasaki’s factory team took part in some regional races on a redesigned KX450F-SR, the race bike that will form the basis for the production KX450F. Traditionally, the Japanese manufacturers debut their new models in the All-Japan series before following up with a production model that will be used in most other national and international motocross series such as AMA Motocross and Supercross and the FIM MXGP.

Here’s the new KX450F-SR (click on the Tweet to view a larger version of the pictures):

And for comparison, here is the the 2018 KX450F below:

Before we get to into this, let’s observe some caveats: the KX450F-SR is a pre-production race bike, so some of the details you’ll see will not carry over to the KX450F. Components such as suspension, chains, and exhausts may differ from the production model. The engine, chassis and bodywork, however, will be similar to the production version, so that’s where we’ll focus our attention.

At first glance, it’s clear that the engine is new. The cylinder appears slimmer and the cylinder head is significantly larger. On the right side, the new F-SR is missing a kickstarter. Where the kickstarter used to attach, Kawasaki has relocated the oil fill plug (identifiable by the bright green cap).

In case you need further proof the engine is new, the California Air Resources Board  has issued a red sticker certification document for a 2019 KX450F, noting the engine family name is “KX450J”. That last letter is significant as it is changed with every engine update. The current (2016-2018) KX450F has been certified with the engine code “KX450H” (the letter is changed in alphabetical order, but skips “I” because it can be confused with a one or a lower-case “L”). The engine preceeding that was identified as “KX450F” (2012-2015), and before that came the “KX450E” (2009-2011) which introduced fuel injection to the line.

Other changes we can see include a flatter seat, a new swingarm and a revised frame. We can’t get a clear look at the rear subframe but we expect some differences there as well.

Kawasaki typically releases information about its motocross lineup in early June so we expect to hear an official announcement about the 2019 KX450F around then. We’ll have the latest here on Motorcycle.com as it becomes available.

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