Is The Harley-Davidson 103 A Good Engine? Here's What Owners Say

The Harley-Davidson 103 engine is often described by riders as being faster than earlier Twin Cam versions like the 88 or 96, along with having more features like ABS and an oil cooler. That said, it's not perfect. 

The most commonly reported problem among all Twin-Cam engines (including the 103) made between 1999 and 2006 is early wear on the cam chain tensioner — a weak spot in the design. Harley switched to a hydraulic tensioner system in later models, which helped but didn't fully solve it. Riders also frequently bring up heat. Air-cooled 103s can get uncomfortably hot, especially in traffic or hot climates. Twin-Cooled versions (with liquid-cooled heads) fix this, but not every model got that upgrade. These upgraded versions are especially praised for reducing heat in stop-and-go traffic.

If there's one thing nearly every 103 owner agrees on, it's that the engine rewards regular maintenance. The people reporting 50,000 to 100,000+ miles without major issues are also the ones who keep up with oil changes and stay on top of maintenance. A user on the Harley Davidson forum says, "I personally have about 50k on mine without any motor issues. I run good oils throughout, and keep up on maintenance."

Degradation of oil and vibration can accelerate wear on the timing chain and other components. Beyond that, the usual wear items matter. Keeping the fuel system clean, maintaining proper valve lifter preload, and checking for crank runout can help avoid issues.

Is the 103 underpowered? That depends on what you're comparing it to. Against the Milwaukee-Eight 107 or 114, the answer is yes. But that's expected. The M8s are newer and more powerful across the board. But among Twin Cam engines, the 103 High Output (HO) is seen as the peak. Most of the bugs from earlier engines were worked out by the time it launched, and the HO version gives a noticeable boost in torque.

The real-world difference between the standard and High Output 103 is about 5% more torque — it's not huge, but it's enough to make a differenc. The HO version also benefits from better airflow.

The 103 isn't the most powerful Harley engine, but it's good at what it was built for. And based on how many are still on the road today, it did its job well. If you're buying a used Harley with a 103, owners recommend checking for service records. Look for signs of routine care and ask about the cam service history.