Based on our research the 10 best aftermarket motorcycle engine manufacturers are as follows:
- S&S Cycle
- Jims USA
- Ultima
- Merch Motors
- R&R Cycle
- TP Engineering
- Demon’s Cycle
- Hyperformance
- RevTech
- Screamin‘ Eagle
If you want to find out more about these companies and their products, you’ve come to the right place.
We at PowerSportsGuide have compiled the key facts about them under one roof!
Who Makes Aftermarket Motorcycle Engines?
You can find many great manufacturers nationwide who produce aftermarket V-twin motorcycle engines.
These power sources are typically designed as a replacement for Harley-Davidson engines, but they are often used by those in the custom motorcycle industry as well.
Besides complete engines, these companies often market a wide range of aftermarket performance parts and offer services like engine modifications, repairs, and rebuilds.
Let’s get down to the nitty-gritty and talk about these manufacturers in detail!
1. S&S Cycle
There’s no question that S&S Cycle is the most popular aftermarket motorcycle manufacturer right now.
The company has been offering high-quality aftermarket parts and complete V-twin engines for Harley-Davidson motorcycles since 1958. S&S Cycle is headquartered in Viola, WI, but has a second factory in La Crosse, WI.
If you are looking for a dependable aftermarket V-twin providing a solid performance, you can’t go wrong with an S&S engine!
Available S&S engines right now are as follows:
| Model | Displ. (cu in) | HP | Torque (ft-lbs) |
| T134 | 134 | 162 | 151 |
| T124 | 124 | 132 | 133 |
| V124 | 124 | 128 | 133 |
| T111 | 111 | na | 123 |
| V111 | 111 | 116 | 123 |
| V96 | 96 | na | na |
| V96R | 96 | na | na |
| KN93 | 93 | 62 | 84 |
| SH93 | 93 | 96 | 97 |
| P93 | 93 | na | na |
| V80 | 80 | na | na |
| V80R | 80 | na | na |
2. JIMS USA
Just like S&S Cycle, JIMS USA is also known for its high-quality US-built aftermarket motorcycle engines. The factory and headquarters of the manufacturer are located in Camarillo, California.
JIMS offers Twin Cam engines that are also available with Evolution motor mounts. Thanks to this feature, they fit into any aftermarket and OEM Evo frame as well.
It’s safe to say that JIMS engines are specifically engineered for racers and tuners.
The key advantage of these power sources is their extreme heavy-duty construction, featuring thick-walled cases and forged pistons.
Thanks to these features, JIMS engines produce plenty of power out of the box, but they have the potential for producing much more as they tolerate performance modifications very well.
The only drawback of JIMS engines is that they are not street-legal, hence the “Race” tag in their names.
The production JIMS engines are as follows:
| Model | Displ. (cu in) | HP | Torque (ft-lbs) |
| Jims 135″ | 135 | 136 | 135 |
| Jims 131″ | 131 | 130 | 135 |
| Jims 120″ | 120 | 125 | 121 |
3. Ultima
Besides S&S and JIMS, another big name among aftermarket motorcycle engines is Ultima. These engines are known for having great price-per-value ratios and high performance.
The newest line of Ultima engines is labeled “El Bruto” and rated at 110-160 HP depending on the model. Certain El Bruto engines are available with Diamond Cut or Blackout finishes.
Besides this family, Ultima offers three Twin Cam and one Shovelhead 96” engine as well.
Keep in mind that Ultima engines often get mixed reviews, since they can’t beat the quality of S&S and JIMS engines.
Although Ultima engines are assembled in the US, certain parts come from other countries. This helps to keep prices down, but it also discourages many customers from buying these engines.
Available Ultima engines are as follows:
| Model | Displ. (cu in) | HP | Torque (ft-lbs) |
| Twin Cam 100″ | 100 | 100 | 110 |
| Twin Cam 113″ | 113 | 120 | 120 |
| Twin Cam 124″ | 124 | 124 | 140 |
| Shovelhead 96″ | 96 | 90 | 95 |
| El Bruto 100″ | 100 | 110 | 110 |
| El Bruto 107″ | 107 | 115 | 120 |
| El Bruto 113″ | 113 | 120 | 120 |
| El Bruto 120″ | 120 | 130 | 135 |
| El Bruto 127″ | 127 | 140 | 145 |
| El Bruto 140″ | 140 | 160 | 175 |
4. Merch Motors
Merch aftermarket “Big-Block” V-twin engines are manufactured by Merch Motors. This company is located and headquartered in Canaan Forks, New Brunswick, Canada.
Merch engines are designed to fit all aftermarket and OEM Twin Cam and Evolution HD chassis.
Besides selling complete high-quality engines and performance kits, Merch Motors offers repairs and rebuilds for stock engines.
The list of production Merch engines is as follows:
| Model | Displ. (cu in) | HP | Torque (ft-lbs) |
| Merch 100 Stage I | 100 | 90 | 98 |
| Merch 100 Stage II | 100 | 100 | 107 |
| Merch 120 Stage I | 120 | 110 | 125 |
| Merch 120 Stage II | 120 | 117 | 130 |
| Merch 120 Stage III | 120 | 125 | 135 |
5. R&R Cycles
R&R aftermarket V-twin engines are manufactured by R&R Cycles Inc., headquartered in Manchester, New Hampshire.
The company offers complete big-inch V-Twin power mills along with a wide variety of performance parts and packages. These products and engines are very popular among custom motorcycle builders and performance-minded riders.
The size of R&R engines starts at 113” and ranges up to a whopping 155”!
With these remarkable cylinder sizes, these power sources are among the biggest production aftermarket V-twin engines on the market.
The list of production R&R engines is as follows:
| Model | Displ. (cu in) | HP |
| R&R 113″ | 113 | 125-130 |
| R&R 127″ | 127 | 135-140 |
| R&R 139″ | 139 | 145-150 |
| R&R 147″ | 147 | 155-160 |
| R&R 155″ | 155 | 168-173 |
6. TP Engineering
Another reputable manufacturer of aftermarket motorcycle engines is Total Performance (TP) Engineering.
As the name suggests, the company specializes in producing high-performance engines, transmissions, and parts for custom motorcycles and Harley-Davidsons.
Each of their products is proudly manufactured and assembled in the US. What’s more, the manufacturer strictly relies on the best American materials exclusively provided by US suppliers!
The key specifications of TP motorcycle engines are as follows:
| Specs | Displ. (cu in) | HP | Torque (ft-lbs) |
| TP 114″ Emission Comp. | 1860 | 94 | 111 |
| TP 114″ Performance | 1860 | 113 | 121 |
| TP 121″ Emission Comp. | 1975 | 100 | 120 |
| TP 121″ Performance | 1975 | 120 | 125 |
| TP 124″ Emission Comp. | 2024 | 105 | 125 |
| TP 124″ Performance | 2024 | 122 | 130 |
7. Daemon’s Cycle
Daemon’s Cycle was established as a custom motorcycle company many decades ago. Over the years, the company became an industry-giant retail supplier of the finest aftermarket and custom motorcycle parts.
Daemon’s is headquartered in Florida, but they ship their products worldwide. Also, the company still occasionally builds some custom-built bikes.
Taking advantage of their many years of experience in building and modifying motorcycles, Daemon’s dreamed of their Harley-Davidson Evolution-Style engine.
This 114 cu in power source is actually a heavily modified Ultima 113 cu in engine, which is exclusively manufactured for Demon’s Cycle.
Compared to the stock Ultima 113 cu in, the Demon’s 114 cu in comes with many advanced features, including:
- Mahle forged pistons
- Reduced piston speed for less wear on the cylinder walls
- Strengthened crankshaft
- More advanced rocker boxes for adequate cooling
- Thicker head gasket
- Increased rod ratio
- Ultima R1 carburetor
- Special air cleaner
Thanks to these advanced features, the Daemon’s Cycle 114” produces 127 HP with 130 ft-lbs of torque.
8. Hyperformance
Hyperformance is another well-known name in the motorcycle industry. The Iowa-based company offers many high-quality aftermarket parts, complete V-twin engines, along with modification and repair services.
Just like Daemons, Hyperformance engines also rely on other reputable suppliers like R&R and Timken.
You can find the latest Hyperformance engine line here!
9. RevTech
RevTech products are manufactured by the California-based Custom Chrome USA LLC.
Besides RevTech, the mother company owns many other well-known brands including:
- Motor Factory
- Santee
- Jammer Cycle Products
- HR3
- Inferno
- Tour Ease
- C.C. Rider
Besides numerous performance parts, RevTech has developed many great engines over the years in sizes from 88” up to 125”. These power sources were designed to be replacements for stock Harley ‘84-‘99 Evolution engines.
Unfortunately, it seems that RevTech engines are currently unavailable.
| Model | Displ. (cu in) | Bore (“) | Stroke (“) |
| RevTech 125″ | 125 | 4.25 | 4.41 |
| RevTech 115″ | 115 | 4.125 | 4.3 |
| RevTech 110″ | 110 | 4.000 | 4.375 |
| RevTech 100″ | 100 | 4.000 | 4.000 |
| RevTech 88″ | 88 | 3.625 | 4.500 |
10. Screamin‘ Eagle
Contrary to popular belief, Screamin’ Eagle is not an aftermarket engine manufacturer. Instead, this brand is owned and developed by Harley-Davidson!
The American manufacturer understands the needs of their customers, which brought to life the Screamin’ Eagle brand that represents the performance line in Harley’s offering.
Hence, Screamin’ Eagle engines are actually Harley-Davidson engines that come with performance upgrade kits.
The key advantage of these kits is that they are engineered by H-D, which ensures perfect compatibility with regular Harley engines.
On top of that, these kits can be ordered through authorized H-D dealerships, so adding them to a new bike is completely hassle-free.
Takeaways
Although there are many great aftermarket motorcycle engine manufacturers in the marketplace, riders agree that the best of them are S&S, JIMS, Merch Motors, and R&R.
Our pick is definitely S&S for the street and JIMS for the race track.
Other engines may come with more affordable price tags, but don’t forget that you get what you pay for.
If you don’t like surprises, you may want to bite the bullet and invest in a high-quality engine.
It will pay for itself in the long run!
Disclaimer: These charts are for informational purposes only! For more information, please check the official factory manuals!
References:
http://www.ultimaproducts.com/
https://hyperformancemotorcycle.com/
