I used to build engines for a privateer Kawasaki team and know these motors back to front. I even spent most of my time as a Junior racing what was then the KX80.
The engine has increased in size to 84.6cc but is very similar.
Back in its early days, the KX was praised for its rotary exhaust valve, which made the power much smoother, broader and more useable across a much wider rev range.
Kawasaki KX85 OUTPUT
By today’s standards, the stock Kawasaki KX85 motor is a little down on output compared to some of its rivals but it can certainly be improved.
I was lucky enough years ago to get a tech sheet from Kawasaki Japan that instructed tuners to cut out the moon-shaped ports in both sides of the cylinder, on the intake side, to the same diameter. This improved the power drastically. The same service bulletin also recommended having the cylinder re-chromed, as the stock chrome struggled to handle harsh use, and to fit ceramic bearings to the crankshaft. This in turn really sharpened up the power of the Kawasaki KX85, but the next obstacle was to improve the suspension.
The suspension in the Kawasaki KX85 is a little outdated compared to other brands. They are still quality units but they just don’t have the adjustability of the YZ, Husky or KTM. There are a bunch of products on the market that can fix this and it’s certainly an option if you’ve paid a reasonable price for the bike to start with.
As it rolls out of the factory, the Kawasaki KX85 is a great beginner-to-intermediate level bike. It is great for learning to ride on, racing club days or even just trailriding or cruising around the paddocks with your buddies but it needs some upgrading and a few dollars spent on it to make it an elite-level kid’s race bike.
I’m not saying it can’t be done, it certainly has the potential to win races and has done so many times. I’m just saying that to bring it up to the same level as the KTM or Husky needs some dollars.
Not every kid needs or can handle an arm-tearing 85 with rock-hard suspension so if you’re happy with an 85 that has an easy-to-manage powerband and forgiving suspension then the Kawasaki KX85 might just fit your family perfectly. Technical Editor Mat Boyd
Kawasaki KX85 Prices from redbook.com.au
Kawasaki KX85 Price When New
Kawasaki KX85 Price Second Hand