When it comes to choosing the right Harley-Davidson motorcycle, the engine is a big deal. The Twin Cam engine, introduced in 1999, has become a hallmark of Harley’s performance and reliability. But like any major mechanical design, some years of the Twin Cam lineup are better than others. After spending some time researching and speaking with other riders, I’ve learned a lot about which years are best to steer clear of. In this guide, I’ll walk you through the years of the Harley Twin Cam engine you might want to avoid, based on common issues and firsthand experiences.
What Is the Harley Twin Cam Engine?
Before we dive into which years of the Harley Twin Cam to avoid, let’s quickly recap what the Twin Cam engine is. The Twin Cam is a v-twin engine that Harley-Davidson used in many of its models from 1999 to 2017. It was designed to provide more power, efficiency, and durability compared to previous engines, making it a popular choice for riders seeking smooth cruising and reliable performance. However, like with anything mechanical, some years experienced growing pains that impacted their reliability and performance.
1999-2000: The Early Years
The Learning Curve
When Harley-Davidson first rolled out the Twin Cam engine in 1999, it was a big leap forward in terms of technology. But, like many first-year models of any engine, the 1999 and 2000 bikes were far from perfect. These early models were plagued with a few issues that would set the stage for years to come.
Oil Pump Failures
One of the most common issues with the 1999-2000 Twin Cam engines was the oil pump. These engines were notorious for oil pump failures, especially in the 1999 models. Riders reported engine overheating and, in some cases, complete engine failure due to inadequate oil flow. While Harley-Davidson made adjustments to the oil pump in subsequent years, these early Twin Cam bikes suffered from a lack of refinement in the lubrication system. If you’re looking at a bike from these years, it’s crucial to check the oil pump and ensure it’s been replaced or upgraded.
Cams and Tensioner Issues
The 1999 and 2000 Twin Cam engines also had issues with their camshafts and tensioners. The cam tensioners, in particular, were prone to premature wear. In the worst cases, this led to complete engine failure, which is a big red flag when purchasing a used bike. Many riders experienced significant wear on the cam chain tensioners in under 30,000 miles, which is well before you’d expect any serious maintenance on a Harley engine. Keep an eye out for signs of camshaft damage or a noisy engine, as this could point to a problem that was all too common in the early years of the Twin Cam engine.
Common Screamin’ Eagle 110 Engine Issues
| Issue | Common Symptoms | Likely Cause(s) | Potential Consequences | Key Checks / Recommended Upgrades |
| Lifter Failure | Progressive ticking noise, eventual failure | High valve spring pressure, aggressive cams (SE255), heavy valves | Cam lobe damage, debris circulation, engine failure | Check lifter type/age; strongly consider aftermarket lifters (e.g., S&S); check cam condition. |
| Valve Train Issues | Noise, valve guide wear, seal leaks, loose parts | High valve train stress, stiff springs, heavy valves | Poor running, oil consumption, component failure | Inspect valve train components; consider milder cams and appropriate valve springs. |
| Overheating / Excess Heat | Engine running very hot, rider discomfort | High compression, air-cooling limitations | Reduced component life, performance loss | Ensure proper tuning; consider oil cooler, head fans. |
| Oil Leaks / Consumption | Leaks (rear cyl base, head gaskets), burning oil | Gasket design/failure, potential ring/valve seal issues | Oil loss, messy engine, potential internal damage | Inspect common leak points; check service history for gasket replacements; monitor oil consumption. Verify 0906 program completion (if applicable for gaskets). |
| Compensator Failure | Clunking/banging noise from primary drive | High torque output stressing stock compensator | Damage to primary drive components, poor starting | Listen for noise; consider upgrading to a more robust aftermarket compensator. |
| Crankshaft / Bottom End | Vibration, noise, potential bearing failure | Pressed crank vulnerability, high engine stress | Vibration, component wear, catastrophic failure risk | Check for excessive vibration; runout check advised if performing major work. Check inner primary bearing history. |
| Cylinder Liner Issues | (Primarily early models) Potential oil consumption | Manufacturing/design issue in early 110s | Poor sealing, oil consumption | Be aware of potential issue in early (e.g., ’07/’08) 110s. |
| Stalling / Stumbling | Engine cutting out, hesitation | Tuning issues, heat-related problems, other component failures | Poor drivability, potential safety hazard | Ensure proper EFI tune; investigate potential heat or sensor issues. |
1999-2000: The Early Days – A Rocky Start
Why the 1999-2000 Models Can Be Tricky
The first Twin Cam engines came out in 1999. They were a big deal for Harley-Davidson. But they had some issues that made them harder to recommend. These early models were rough around the edges.
Cam Chain Tensioner Problems
One of the biggest problems was the cam chain tensioners. They wore out too quickly. This caused a lot of trouble, especially for riders who didn’t replace them early enough. When the tensioners failed, the cam could get damaged. That meant costly repairs. Many riders found this out the hard way.
Oil Pump Issues
Another common issue was the oil pump. Some of the 1999-2000 bikes had problems with oil pressure. This caused the engine to overheat. Over time, this could lead to engine failure. So, it’s important to check the oil pump if you’re buying a bike from these years.
What You Can Do
If you’re looking at a 1999-2000 Twin Cam bike, make sure the cam tensioners have been replaced. That’s a must. Also, check the oil pump. You don’t want to deal with these problems after buying the bike.
2001-2006: Some Improvement, But Not Perfect
Better, But Still Issues
By 2001, Harley had made some changes. The bikes got a little better. But the problems with the cam tensioners didn’t go away. The tensioners still wore out too quickly, especially on high-mileage bikes. Even though they were improved a bit, many riders still needed to replace them.
Exhaust Leaks and Valve Problems
Another issue was exhaust leaks. Some bikes from this time had issues with exhaust gaskets and flanges. This could cause power loss or even damage to the engine. It’s a small problem, but it’s one you don’t want to miss when buying a bike from these years.
Valve Problems
Some riders also faced valve problems. The valve seats could erode, which caused misfiring or a rough engine. This didn’t happen to every bike, but it was common enough to keep in mind.
The 2004-2005 “B” Motor
The 2004-2005 models had a “B” motor, which was better than earlier versions. This engine had some nice upgrades, like stronger components. But, it still wasn’t perfect. Some riders still had tensioner issues, and the valves could still cause trouble. The engines were stronger, but some bikes ran into issues sooner than others.
2007-2010: A Step Forward, But Still Watch Out
The 2007 Model: A Turning Point
By 2007, Harley made significant changes to the Twin Cam engine. They introduced the 96 cubic inch engine, which was a nice upgrade. It had more power, smoother performance, and improved cooling. The 2007 models also got some upgrades to the cam chain tensioners, which was a relief. But don’t get too excited just yet—there were still some problems.
The Big Problem with the 2007-2010 Twin Cam: The Cam Tensioner
Even though the cam tensioner was improved, it didn’t always fix the problem. Many riders still faced premature wear. The cam chain tensioner wasn’t fully reliable until 2007, and even after that, the issues didn’t completely go away. It still needed to be checked regularly, especially in high-mileage bikes.
2009-2010: The 103 Cubic Inch Engine
In 2009, Harley bumped the engine size up to 103 cubic inches. This meant even more power. The 103 motor was a strong performer, and it handled highway speeds better than earlier models. But, it still faced the same cam chain tensioner issue that lingered for years. If you were buying a 103 Twin Cam bike, it was still important to check that the tensioners were upgraded and in good condition.
What You Should Look Out For
For the 2007-2010 models, the best thing you can do is check the cam chain tensioners. Even though there were improvements, they still had issues. Also, if you’re buying a 2009 or 2010 model, make sure to inspect the engine for signs of excessive wear, especially around the cam chest. Regular maintenance is key, but the cam tensioners still need special attention.
Early Twin Cam (1999-2006) Cam Tensioner Issues
| Issue | Affected Years/Models | Symptoms | Consequences | Inspection | Recommended Fixes (Pros/Cons) |
| Spring-Loaded Tensioner Failure | 1999-2006 TC88 (A & B) | Often none until failure | Premature wear of plastic shoes; plastic debris contaminates oil; oil pump damage/failure; potential catastrophic engine failure due to oil starvation | Visual inspection required (cam chest removal) | HD Hydraulic Kit: Reduces shoe wear, improves reliability over stock; still uses plastic shoes (wear item, ~40k mile life); requires payment for factory design flaw correction. <br> Gear Drive: Permanent fix (eliminates chains/shoes); potential performance gain with new cams; higher cost; requires crankshaft runout check (<0.003″ typically needed). |
2011-2016: Improving, But Not Perfect
2011: The 103 Cubic Inch Gets a Boost
By 2011, Harley made more improvements. The 103 engine got a bit more refined, and they started adding better cooling systems. These years saw a better overall balance of power and smoothness. But here’s the catch: while the 103 engine was much better, it wasn’t entirely without issues. The cam chain tensioners were still a concern, although Harley did introduce some upgrades to the system that made them more reliable.
The Tensioner Issue Still Lingers
Even in 2011 and later, the cam chain tensioner problem wasn’t fully solved. While the design had improved, some owners still experienced failures. Riders often reported issues with tensioners wearing out prematurely, especially on bikes with higher mileage. Even though Harley made strides, they hadn’t fully addressed the root of the problem.
The 2014 Rushmore Project and Twin Cam 103B
In 2014, Harley launched the “Rushmore Project” with some exciting changes. This included better technology, more comfortable ride features, and updated styling. They also introduced the Twin Cam 103B engine. This version had improved components to address some of the issues from earlier years, but it still used the same basic design. While it was a step forward, it didn’t completely eliminate the previous issues. The 103B engine was a solid performer, but if you were buying one used, the cam chain tensioner issue was still something to keep an eye on.
What to Check in the 2011-2016 Models
If you’re looking at a 2011-2016 Harley with a 103 engine, make sure the cam chain tensioners have been upgraded. If you’re buying a bike from this era, don’t be afraid to ask for service records to see if the tensioners have been replaced. Regular maintenance can help keep your bike running well, but this is one of those things that can be expensive if it fails.
Essential Pre-Purchase Checks
Beyond standard used motorcycle inspection points, focus on these Twin Cam specifics:
- Cam Chest Verification (1999-2006): This is non-negotiable. Demand documentation of tensioner upgrade. If unavailable, assume the worst and budget for immediate replacement. For 2007+ models, understand the hydraulic system is present but the shoes are still wearable long-term.
- Engine Noise: During startup and test ride, listen intently. Ticking noises (especially on a 110) could indicate lifter/valve train issues. Knocking or deep rumbling could suggest bottom-end problems. Loud clunks from the primary side on startup/shutdown might point to compensator issues.
- Oil Leaks: Thoroughly inspect the engine for any signs of oil seepage or active leaks. Common areas include rocker box covers, cylinder base gaskets (especially the rear cylinder), pushrod tubes, primary cover, and transmission seals.
- Performance and Running Condition: Test ride the motorcycle through various RPM ranges. Note any stalling, stumbling, hesitation, or surging. Assess engine heat, particularly at idle. Ensure smooth clutch operation and gear shifting.
- Maintenance Records: Request any available service history. Regular oil changes using quality synthetic oil are particularly important for mitigating wear, especially on high-stress engines like the 110. Records may also show previous repairs or upgrades.
- Crankshaft Runout Inquiry: While a full runout check during a pre-purchase inspection is often impractical due to the labor involved , it’s worth asking the seller if it has ever been measured, especially if the bike has performance modifications or if the buyer intends to install gear drives. If excessive vibration is present, runout becomes a stronger suspect. A knowledgeable independent mechanic performing a general pre-purchase inspection might offer insights based on noise and vibration.
FAQs: Harley Twin Cam Years to Avoid
Q1: What are the Harley Twin Cam years to avoid?
A1: Avoid Harley Twin Cam models from 1999–2002 due to cam chain tensioner issues that can lead to engine failure if not fixed early.
Q2: Why should I avoid 1999 to 2002 Twin Cam Harleys?
A2: These years had weak cam chain tensioners that wore out fast, risking engine damage if not replaced or upgraded in time.
Q3: Did Harley fix the cam chain issue in later Twin Cam years?
A3: Yes, Harley improved the system in 2007 by switching to a hydraulic tensioner, making the engines more reliable.
Q4: Are all Twin Cam engines bad or just early models?
A4: Not all are bad. Most issues were in early years. Post-2007 Twin Cams with upgrades are seen as more reliable and smoother to ride.
Q5: What engine replaced the Harley Twin Cam?
A5: In 2017, Harley introduced the Milwaukee-Eight engine, offering more power, better cooling, and smoother rides than the Twin Cam.
Q6: Is it safe to buy a used Harley Twin Cam now?
A6: Yes, if it’s well-maintained and upgraded. Check if the cam chain tensioners were replaced, especially on pre-2007 bikes.
Q7: How can I tell if my Harley has cam chain issues?
A7: Signs include ticking noises, poor power, or metal in the oil. Early checks can save the engine. Ask a mechanic to inspect it.
Q8: Can I upgrade an older Twin Cam to avoid engine issues?
A8: Yes, many riders upgrade to hydraulic tensioners or gear drives. This fixes common problems and boosts engine life.
Q9: Which Harley years are best if I want a Twin Cam?
A9: Look for models from 2007 to 2016. These have fewer cam issues and better performance, especially with regular care.
Q10: What’s the best way to research Harley Twin Cam problems?
A10: Check rider forums, service records, and trusted reviews. Learning from other owners helps spot real issues before buying.
2017 and Beyond: The End of the Twin Cam Era
A Major Shift with the Milwaukee-Eight
In 2017, Harley-Davidson made a big change by introducing the Milwaukee-Eight engine. This was the end of the road for the Twin Cam. The Milwaukee-Eight was designed to fix many of the Twin Cam’s long-standing issues, including the cam chain tensioner problem. It featured improved cooling, more power, and better reliability. The shift to the Milwaukee-Eight marked a fresh chapter for Harley, with fewer complaints about engine issues.
Why the Twin Cam Engine Isn’t All Bad
Even though the Twin Cam had its share of issues, it’s important to remember that it’s still a solid engine. Many riders have enjoyed their Twin Cam Harleys for years without major problems. The key is in the maintenance. If you keep on top of things, especially the cam chain tensioners, the Twin Cam engine can still provide plenty of joy.
Should You Avoid All Twin Cam Models?
It’s tempting to write off all Twin Cam bikes as problematic, but that’s not necessary. Sure, certain years have more issues than others, but many people still love their Twin Cam Harleys. If you’re willing to put in a little extra work for peace of mind, you can have a great riding experience with a Twin Cam. The models before 2009 should be avoided if you want a hassle-free ride, but the later years, especially from 2011 onwards, offer better performance and fewer headaches, assuming you stay on top of maintenance.
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