Harley Evo Vs Twin Cam: Which Engine Systems is Better?

In the late 1990s and early 2000s, the Evo design was developed & used in Harley Sportstar bikes to dampen vibration and reduce engine noise and bleakness. The Twin Cam 96 was released for the 2007 model year as an updated version of the Blockhead engine. Thus, the endless conflict between Harley Twin cam and Evo is always.

That’s where we come in. We have researched in-depth on these giant engines and we’ve got clear answers for you. So, let’s dive in and see the basic facts about the two in our Harley Evo vs Twin Cam Engine System comparison.


Comparison Table:

Difference in Harley Evo Harley Twin Cam

Faster and lighter engine.

A little heavier and slower engine.
 Cams Gear-driven single cams Chain-driven dual cams
Engine Power 1340CC  1450CC 
Transmission Evo is available from four to six-speed transmissions. A twin cam engine is available only with six-speed transmission.
Cylinder System Liquid-cooled single-cylinder engine system. Rubber-mounted twin cam has two valves per cylinder. Where the cylinders are placed in a V shape and share a common crankshaft.
Fuel Injection Comes with a dry sump injection system with an external tank. It has an internal oil reservoir and a separate sump.
Compression Ratio The compression ratio of Harley Evo is 9:1. The compression ratio of the twin cam is 8.35:1.
Pushrod System This engine has a pushrod system for the rocker’s arms.  Twin Cam’s hydraulic lifters automatically adjust the clearance of the pushrod during operation.


About Harley Evo (Evolution) Engine

The Evolution engine is one of the first motorcycle engines made by Harley. It played an important role in reviving Harley’s success when the business was facing a severe crisis.

This engine system has a high engine shift capacity of 1340CC. Thus, it’s best for the Harley Davidson Big V-twins motorcycles. As a result, the Evolution engine took charge of the Shovelhead engine systems in early 2000. This is to say, that was the last year the Evolution engine got sited in a manufacturing company with its traditional FXR4 models.

From records, most choppers operate with. The structure of the Evo’s heads and cylinders consists of aluminum metal. Therefore, it helps to lower the weight of a motorbike as compared to those made of cast iron materials. As a result, working with it seem super easy with less effort required.

Plus, this construction makes it robust and reliable sure to last you years of cruising. Above all, it acts as a great thermal conductor. Thus, it helps to improve the air cooling efficiency for a brilliant performance.

The high engine movement capacity gives incredible power for running their motorcycles. Despite the goods of the Evo, it faced high production and design flaws after its invention. For instance, its crankcase was prone to breakages. Plus, the left-side case gave annoying leaks of fuel. Besides that, the cylinder base gaskets tend to leak while the cylinder studs often get drawn.

Additionally, it runs on a single camshaft that is gear-driven and is located above the crankshaft axis. As a result, it makes noises like clicking and whining that are against EPA regulations.


  • The engine is very powerful
  • It is very reliable
  • It is very easy to work on


  • Base gaskets like to leak
  • Produces significant noises and emissions


5 Common Evo Engines Problems

1. Engine knocking: Low-octane fuel is typically the culprit here, and using better gas will fix the problem.
2. Poor fuel economy: A poor carburetor or ignition system is frequently to blame for this.
3. Hard starting: This can be brought on by a number of issues, such as a low battery, dirty spark plugs, or a malfunctioning carburetor.
4. Rough idle: A rough idle is typically brought on by either a filthy carburetor or an improper idle mixture.
5. Stalling: A filthy air filter, a poor fuel mixture, or an ignition system issue are just a few of the potential causes of this. Here, if the problem is with the air filter, there is an option of replacing it with the stage-1 best air filter made for Evo engines
6. Overheating: A leaking coolant system or a bad water pump are the usual causes of overheating.
So, if your Evo Engine is having trouble, then you may need the best carburetor to run your engine smoothly. 

About Harley Twin Cam Engine System 

The Harley Twin Cam aircooled engine is a 45degree Vtwin engine with two cylinder heads and four valves per cylinder. This engine was presented in 1998 for the 1999 model year and was used in HarleyDavidson motorcycles until 2006 when it was replaced by the HarleyDavidson MilwaukeeEight engine.

Additionally, this engine was introduced as a replacement for the Evolution engine. The engine was significantly lighter than the Evolution engine and produced more torque and horsepower. It was used in all HarleyDavidson models until 2006 when it was replaced by the MilwaukeeEight engine.

Besides that, it comes with better fuel injection as compared to the models Evo ever had.

The biggest pro with Twin Cam is this engine’s intra-brand respect. Models like the Dynas, Softails, Sportster, Touring, and others have this engine system. Most importantly, this engine has continued to get revisions to fit new line models.


  • Powerful performance
  • Friendly to the environment
  • Excellent fuel injection


  • The ’99 to ’06 models had a weak oil pump


5 Common Problems with Twin Cam 

1. Oil Leaks: The most common issue with Twin Cam engines is oil leaks. These can occur from the base gasket, head gasket, or even the oil filter itself.

2. Excessive Vibrations: Another common issue is excessive vibrations. This is often caused by an imbalance in the crankshaft or a problem with the engine mounts.

3. Engine Knocking: A knocking noise coming from the engine is usually caused by a problem with the pistons or connecting rods.

4. Camshaft Problems: The camshafts in Twin Cam engines are known to wear out prematurely. This can cause a loss of power and poor engine performance.

5. Coolant Leaks: Coolant leaks can occur from the water pump, radiator, or even the hoses. These leaks can cause the engine to overheat.


Twin Cam vs Evo Engines: What’s the Difference?

The torque power delivered by both Harley Evo and Twin Cam is about the same. Meaning that they both provide high performance down the road. But, Twin Cam would still beat Evo even if they both get developed to meet similar standards.

In other words, it has plenty of tweaks included in its design. For example, it has stouter crankcases. Also, it has the ability to give more space for improving displacement. If built to perfection, Twin Cam will provide you with a hassle-free performance and peace of mind.

Finally, Harley Davidson’s Evo and Twin Cam Engines are great and powerful engines worldwide. Plus, it’s known to give a top-notch performance despite flaws in its design and production. However, they have continued to get modified into better systems.

When deciding between these engines, consider the cost and your budget needs. Also, check for its ability to service, as well as the lifespan of the engine. Thus, make your judgments on the best one for you.


Similarities between Harley Evo And Twin Cam Engine Systems

There are a few key similarities between Harley Evo and Twin Cam engine systems. Both systems have a fourstroke combustion cycle, with intake, compression, power, and exhaust strokes. The remaining exhaust is good enough but if you want there is a to modify it with the best performing exhaust and best sounding exhaust. 

In addition, both systems also have pushrodoperated overhead valves, with the intake and exhaust valves located in separate cylinders. And finally, both systems use a chaindriven camshaft to operate the valves.


Final Thought- Is the Evo better than the Twin Cam?

By comparing Harley Evo vs Twin Cams we got that both units offer a nice ride. Both have benefits, differences, and features that may make one better for your needs. Harley-Davidson Evo’s four-speed transmission makes it faster and lighter. With its six-speed transmission, Twin Cam is slower and heavier, but its automated gearbox delivers a more comfortable ride.

So take your time to feel the best one for your motorcycle.



Q. What is the cost for rebuild a Harley Evo engine? 

These prices depend on how much shops pay their workers. The cost of a top-end rebuild is around $500.00, and the cost of a top-end rebuild with boring may be over $700.00. However, a new crate engine installation costs approximately $3500 – $4000. 2015 Harley Davidson Evo model costs $18,899. 


Q. What is the rebuild cost for a Twin Cam engine?

It costs around $4500- $5000 to rebuild a Twin Cam engine. However, a new twin-cam engine costs $18,000 to $38,000.


Q. How long do Harley twin cam engines last?

Many Evo engines could easily travel 100,000 miles and up to 250,000 miles with minor issues. Twin Cams had some early problems, but we have seen a traction control system with 225,000 miles. Additionally, the Milwaukee-8 is too new for accurate mileage checks. An engine on a bike that is well-maintained can last forever.


Q. What is the average life of a twin cam 96?

Normally 100,000 miles. The twin-cam engine has a double camshaft. This opens and closes cylinder head valves to let air and fuel into an engine. The bottom line is that more lifters on your cam open and close valves faster, enabling more air into your cylinders.


Q. Is Milwaukee 8 better than twin cam?

Yes, M8 heads are more powerful than Twin Cams. For example, the Milwaukee-Eight 107 is 11% faster at 0-60 and 60-80 mph than Twin Cam High Output 103. Likewise, Milwaukee-Eight 114 is 8% faster at 0-60mph and 12% faster at 60-80mph than Twin Cam 110.

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Hello, this is Adam Willam, the owner and author of the website- "motobikekit.com". I have been passionate about biking since I was a child and have always been fascinated by the mechanics of how bikes work. When I became old enough, I started my own business of repairing and customizing bikes. By doing this I have quickly gained a reputation for being the go-to guy for bike repairs and customizations and have been running my shop successfully for many years.

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