ASK THE MXPERTS: MYSTERIOUS 2024-2025 KAWASAKI KX450 OIL LEAK

ASK THE MXPERTS: MYSTERIOUS 2024 KAWASAKI KX450 OIL LEAK

MXA’s first 2025 Kawasaki KX450 leaked oil at the right-side cover. Guess what? So did our second KX450.

BUBBLING CRUDE
Dear MXperts,
My new 2025 Kawasaki KX450 has oil coming from somewhere on the right side of the engine. I originally thought it was coming from the oil-filter canister, but that proved to be wrong. I’m stumped. Help!

Here is a short story. MXA’s 2025 Kawasaki KX450 suffered a minor crash in the first moto where the KX hit the ground with the right side of the engine in the dirt. The test rider picked it up and continued on to win the 450 Pro moto. When he got back to the pits, he noticed oil on the toe of his boot, but we couldn’t find where the oil was coming from. We checked the oil level and sent him back out for the second moto. This time, when he came back to the pits, there was a lot more oil on the right side of the KX450’s case. But, this time we could see that the oil was oozing out of the gasket on the side case (just under the cylinder). we had four hours on the engine.

We called Kawasaki to see if they could send a mechanic from the press relations department to look it over and replace the gasket. Kawasaki said that they would rather just give us a new bike, because they were in the middle of a series of big press introductions and didn’t have any spare mechanics. The bike that they gave us had 2.6 hours of break-in time on it, and it lasted another three hours before it began to leak oil out of the right side of the case. Luckily, we were with Kawasaki on this day, and they said they’d never seen that problem before. But, we asked a hard-core KX450 racer, and he said that he had to replace the right side-case gasket three times last year. In the end, we asked Kawasaki to fix our original KX450 when they had time and give it back to us (and we would return the second KX450 they gave us. Given our experience, we are pretty sure that your side-case gasket is the source of your oil leak, as it was in the case of our two oil leaks in two weeks.