Generally speaking, the most reliable motorcycle engines are the large-displacement inline-six and flat-six (boxer) engines. They run at lower compression ratios and deliver less power than inline-four engines, which leads to higher reliability and durability. You can find these power sources in the largest touring bikes like the Honda Gold Wing or in some touring BWM bikes. But if you are looking for a smaller bike, you can find many on the market with reliable small-bore motorcycle engines.
If you want to find out more about the best motorcycle engines, you are in the right place!
Factors That Affect Motorcycle Engine Reliability
Many factors affect the reliability of motorcycle engines, but the most important ones are as follows:
- the complexity of the engine
- the layout and number of cylinders
- displacement
- cc/HP ratio
- compression ratio
- cooling system
- quality and brand
Let’s drill into the details and briefly take look at these factors!
When it comes to engine reliability, the rule of thumb is that if an engine has an extremely complex design, it inevitably leads to high manufacturing costs and less reliability.
This is the reason why complex motorcycle engine layouts like Wankel or V5 have not become very popular. These complex engines feature odd designs with too many parts, which result in lower reliability and higher manufacturing and running costs.
Regarding the most common designs, different layouts are developed for different purposes. For instance, four-cylinder inline engines are built for maximum performance.
This is why you can find inline engines in the fastest sport and sport touring bikes.
These power sources have higher compression and smaller pistons that can move much faster. Therefore, they can run at much higher RPMs and offer the highest power and top speeds in each class.
But higher performance always means less reliability and durability.
This is why the most reliable motorcycle engine layouts are the flat-six, flat-four, and inline-six configurations. These engines have large-displacement cylinders, but still offer significantly lower HP than engines on smaller inline-four sportbikes.
How it is possible? The answer is in the different compression rates.
Sportbike engines have high compression rates, so they crank out more HP from the same displacement than any other bike engines.
If you have doubts, just take a look at the HP/cc ratios of some popular motorcycle models:
| Model | cc/HP | HP | cc | Category |
| Yamaha Star Venture | 21,8 | 85 | 1854 | Touring |
| Harley-Davidson Street Glide Special | 18,7 | 100 | 1868 | Cruiser |
| Honda Gold Wing GL1800 | 14,5 | 125 | 1812 | Touring |
| Honda NC750X | 13,8 | 54 | 745 | ADV-touring |
| BMW K 1600 GTL | 10,3 | 160 | 1649 | Touring |
| Yamaha Super Tenere | 11,0 | 109 | 1199 | Adventure |
| Kawasaki Concours 14 | 8,5 | 160 | 1352 | Sport-Touring |
| KTM 1290 Super Adventure R | 8,2 | 160 | 1309 | Adventure |
| Suzuki Hayabusa | 6,8 | 197 | 1340 | Sport |
| Ducati Panigale V4 | 5,2 | 214 | 1103 | Sport |
| Suzuki GSX-R1000 | 5,0 | 199 | 1000 | Sport |
| BMW S1000RR Sport | 4,9 | 205 | 1000 | Sport |
| Honda CBR1000RR | 4,7 | 215 | 1000 | Sport |
As you can see, sportbikes deliver many times more HP from the same engine displacement than touring and adventure motorcycles. Therefore, they are less reliable, and you can also expect to have much less durability.
Besides the features and performance of the engine, the brand is also an important factor.
Many dealers and riders say that the most reliable motorcycle engines are made by the “big four” Japanese manufacturers. The reliability of Honda motorcycle engines is legendary, but it’s safe to say that the other brands (Kawasaki, Suzuki, Yamaha) also produce very good engines.
However, you can also find high-quality engines in some European and U.S.-made motorcycles as well.
Are you wondering what these engines are? Keep reading!
Which Motorcycle Engine is the Most Reliable?
Based on the above-discussed facts, the most reliable motorcycle engines are the six-cylinder (flat-six and inline-six) and flat-four engines, which are typically found in the biggest touring motorcycles. The most well-known bikes in this category are Honda Gold Wings powered by an 1812cc, 130 HP, flat-six and the BMW K 1600 series that comes with a 1649cc, 160 HP, inline-six engine.
These engines run very smoothly and at low RPMs, so with proper care and maintenance, many of them can even run hundreds of thousands of miles!
But of course, only very few buyers are looking for these touring bikes, as they have many disadvantages. Although they are considered to be the most durable of motorcycle engines, if they need to be repaired for any reason, the repair bill could be substantial due to their high level of complexity.
What’s more, these bikes are heavy, bulky, and come with very hefty price tags. Thus, they are not for everyone.
If you are looking for a smaller bike but engine reliability is an important factor for you, you should stick with the touring and adventure category.
The power sources of these bikes have a moderate performance and lower compression, which is the key to higher reliability.
The most common engine layouts in these bikes are the V-twin, parallel-twin, and triples.
You can find many good bikes in these categories from the Honda Africa Twin to the Yamaha XT1200Z Super Tenere, both of them powered by a reliable parallel-twin engine.
But if you are looking for something really reliable and durable, you should take a look at the HONDA NC750X.
This bike features a 745cc parallel-twin engine, which puts out only 54 HP. This “car engine-derived” power source offers outstanding fuel economy and reliability!
If you are considering buying a lightweight bike, it’s recommended that you steer clear of single-cylinder engines. Although they feature a simple design, their cylinders have to work much harder and also cause much more vibration.
Because of this, you may want to consider a twin or triple-cylinder engine. These power sources work well in smaller bikes, and cause significantly less vibration.
Conclusion
When it comes to the reliability of motorcycle engines, the general rule is that the lower compression the engine has the more reliable and durable it is. The number of cylinders is also an important factor as the most reliable motorcycle engines feature no less than six cylinders.
You can find these engines in the biggest touring motorcycles like the Honda Gold Wing, or the touring BMW bikes.
If you are in the market for a smaller bike, you can’t go wrong with a middle-weight touring or adventure bike.
These machines are typically powered by a V-twin, parallel-twin, or triple engine depending on the model. Don’t forget that the most durable and reliable engines feature low compression and cc/HP rates.
For instance, Yamaha Star Venture has a 1854cc engine that puts out 85 HP (cc/HP: 21.8), while the Honda CBR1000RR cranks out 215 HP from a 1000cc engine (cc/HP: 4.7).
You can guess which engine will be more reliable and last longer!
