Harley Davidson Evo VS Twin Cam – What’s Actually Better?

In the 1990s, Harley Davidson decided to split its audience into two main camps. The first one says that traditional Evolution engines are the best, while the second one is sure that the newer Twin Cam engines are much better. We've been asked many times what we think about these two main types of Harley Davidson motorcycle engines, and we've finally decided to write an article about that.

In our today's article, we won't say much about the motorcycles, the pros and cons of them, and also about the complicated technical side of the question. We'll try to figure out which type of engine is the best for Harley motorcycle buyers.

The most important things that we'll outline are as follows:

1. Technical solutions in Twin Cam and Evo engines.
2. The practical side of the engines - which one is better?
3. Longevity and reliability of the Evo engines vs Twin Cam engines.
4. Which engine is better for different types of riding?

Let's get started!

Evolution Harley Davidson engines - main facts

This engine was introduced in 1984 and it's still a very popular choice. Now they have numerous kinds of Evo engines for sale - starting with 883 cc and finishing with 1337 cc. These engines aren't very big and powerful, they are all-purpose for motorcycles and are really reliable.

Some experts say that the Evo engine actually saved the company from bankruptcy back in the 1980s. This was the last hope to get out of the crisis and start selling more motorcycles. And this worked really well.

Here are some facts about the Evo engine:

• its head and cylinders are made of aluminum which helps reduce the weight of the whole unit;
• air cooling appeared to work well because aluminum is a good heat conductor;
• the Evo engines in Sportsters and in Big Twin bikes were extremely different;
• the engine is very rebuildable, you can repair it after any problems and damages;
• the engines are quite reliable, they can go around 80 000 to 100 000 miles.

For a bike engine, to have a 100 000-mile longevity is a pretty good thing. The engine should be serviced regularly and cared well for in order to show that mileage. But anyway, we know guys who have ridden their HDs even longer than that. Evo engines are really good even now when you can find a lot of modern technologies.

Twin Cam Harley Davidson engines - main facts

In 1998 Harley Davidson introduced bigger Twin Cam engines and they were producing the engines up until 2017. These engines differed much from the Evolution engines but they also shared many common features with numerous other Harley Davidson engines.

The important fact is that the company managed to gather all the well-known technologies and to create a new technological engine for its big bikes.

Here are some features of the Twin Cam engines:

• apparently, they have two cams, this is the second model in HD history that uses two cams;
• the displacement of these engines varies from 1450 cc to 1801 cc;
• a wonderful oil pump (internal) construction allows the pump to be more efficient and create higher pressure;
• the combustion chamber allows for more efficient fuel burn and better compression than in Evo engines;
• the engine is air-cooled, though some modifications had small liquid cooling circles in heads.

The engine used classic technologies but it was a cutting-edge product at the time when it was first introduced. Of course, many models of motorcycles left the Harley Davidson factories with this type of engine.

Twin Cam is a legend, but in 2017 it appeared to be too old and it was replaced by other technologies. Of course, thousands of Harley Davidson fans will still say that this engine is the best option you can buy.

What about fuel consumption?

Well, not many Harley Davidson buyers really care much about the fuel consumption of their bikes. But the reality is not that positive. If you drive your motorcycle with an Evo engine carefully, you can get around 29 MPG of gas mileage. This is not good at all, some comfort-class cars will have the better fuel economy.

The problem is that the Evo engine is old technology. When it was engineered, people didn't care much about ecology and gas consumption. They just wanted to have fun when driving.

The Twin Cam engine was introduced right after the world's economic crisis. So this engine has to be economical, otherwise, it would just lose the competition on the market. So, bigger and more powerful Twin Cam engines burn much less fuel. An average motorcycle equipped with the Twin Cam engine is capable of showing around 38 MPG of gas mileage.

It's still not very good. Some sports bikes and crotch rockets show better gas mileage than the HD with Twin Cam engines. But these are really big and heavy bikes that are made for fun riding. So, the consumption is not that bad.

What's the longevity of Harley Davidson engines?

Longevity is another wonderful question you will have to answer before choosing the engine you want to have. Before we say about the miles, let's also make it clear that all Harley Davidson engines that were introduced up to 2000 are very rebuildable. They can be repaired no matter what has happened with them. These engines are actually very reliable.

But if your Harley Davidson has huge mileage on the clock, you will still spend a lot of money to keep it on track. Sometimes, it's really more lucrative to buy a newer bike.

So, here's what we can say about longevity:

• the Evo engines live up to 80-100 thousand miles;
• all Evo engines are rebuildable and can be repaired easily;
• all Twin Cam engines will survive up to 120 000 miles;
• the repair is much harder and more expensive to complete;
• both engines will still have a lot of parts offered on the market.

In terms of longevity, all classic Harley Davidson engines are pretty good. But you have to look at the engine type. Evo engines are much cheaper to repair. But finding good parts is a harder task. While Twin Cam engines have more complicated construction and are more expensive to repair when they have high mileage. But finding good parts for Twin Cam engines is not hard at all.

What are the main problems of Evo and Twin Cam engines?

We decided to investigate the main problems that Harley Davidson engines show. We concentrated our research on the Evo and Twin Cam engines, but actually, all engines of those epochs have pretty much the same troubles.

We'll start with the Evolution engines of Harley Davidson and its main problems:

1. Bad starting. Especially, the engine may start poorly when it has high mileage or the electric wiring has some issues.
2. Speed sensor malfunctioning. This is a cheap sensor that should be in your pocket if you want to drive your Harley Davidson with no stress.
3. Overheating issues. Well, this happens to air-cooled engines, so be careful and not rev up your Evolution engine too much and too long.
4. Oil pump malfunctioning. This will lead to low oil pressure and hard wear of the engine block and piston.
5. Black smoke. When the piston ring is not functioning as it should, black smoke occurs. Usually, it's the problem of high-mileage engines.
6. Cam chain issues. Most of the issues are connected to the cam chain tensioner. But if you service your motorcycle on time, the problem shouldn't bother you.
7. Ignition problems. The spark plugs may go off very fast because of the old ignition system. Starting your motorcycle becomes hard.

Also, we've asked people on specialized forums whether they had problems with their Twin Cam engines.

And here's what we've found out:

1. Cam chain problems. The design is poor, some plastic elements just wear out and cause problems. This brings big problems with cam chains.
2. Engine smoking. Again, the piston rings wear out and start leaking some oil into the combustion chamber which brings oil consumption and black smoke.
3. Problems with engine block if it has been tuned like Stage 2 or Stage 3. Any tuning is a bad idea with Harley Davidson engines.
4. Total engine block wear because of poor maintenance. Your engine will not survive even 40 000 miles if you don't change the oil regularly.
5. Numerous minor problems in different model years like bearing issues, valve seals issues, etc.

You can see that both engines have some problems, but the Twin Cam is more reliable and it can go more miles until it drops.

Final words

Both Evolution and Twin Cam engines are legends in the motorcycle world. These technologies are pretty reliable and don't tend to ask for a lot of maintenance and service. Both engines can easily go up to 100 000 miles and even more. For a motorcycle, this is a huge mileage. So even if you want to buy a used bike with Evo or Twin Cam engines, you can easily do it (but don't forget to check thoroughly whether a bike had no documented issues before).