The 10 Best Japanese Motorcycles for Aftermarket Tuning

Nissan GT-R R34

In the tuning world it is safe to say that most motorcycles are more popular than the cars. The truth is that some cars owe their popularity to the engines under their hoods. While most Japanese engines, in their factory configuration, are not insanely powerful, tuning unlocks its full potential, taking the car’s performance to the next level. A large number of JDM engines are sought after for their reliability, strength and durability. Add that to the fact that they are known for their lightweight nature.

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It’s no secret that the power output of the best JDM engines differs from those in other markets. Most of the engines in this list were limited to a maximum power of 276 hp under the Japanese ‘Gentleman’s Agreement’ introduced in the 1990s. As a result, these Japanese engines made for export were very reliable and had enormous upgrade potential. In their strongest moods, some became so powerful that they made figures on paper almost a joke. And now, thanks to aftermarket tuning parts and amazing power outputs, these Japanese engines are among the best in the world, with many having a cult-like following. The “Gentleman’s Agreement” may have faded in the mid-2000s, but the Japanese artistic engine for building great motorcycles still lives on to this day. Here are the 10 best Japanese motorcycles to tune.

10 Mazda Rotary Engines (13B-REW)

Invented in the 1950s by Felix Wankel, the rotary engine became popular among hot rodders and kit car builders for its unbeatable tuning potential and unrivaled power-to-weight ratio. They pack a big punch in a very small space – a quad-rotor Wankel engine (smaller than a typical flat-six) produces the kind of growl you’d find in a V8 engine.

The motor spins fast and hard, producing approximately 150 horsepower per rotor without forced induction. Add a turbocharger and the sequential engine can reach powers of over 300 horsepower per rotor. Their design produces hot exhaust gases that can easily spool up large turbos. The 280 hp 13B-REW in the Mazda RX-7 was popular for its high power and lightweight character; it was the world’s first mass-produced sequential turbo engine.

9 Honda B-series engines

Love them or hate them, Honda motorcycles dominated the tuning scene with their inline fours between the 1980s and the 2000s. Honda enthusiasts adore them for their incredible design, both standard and even more so when tuned. It is the engines that introduced gearboxes in VTEC technology.

The first generation B16A introduced in 1989 could produce 160 horsepower from just 1.6 liters (1,595 cc) at 7,600 rpm without forced induction. Even by today’s standards, that’s insane considering the size of the engine. Honda later introduced the B16B in the Civic Type R 1997-2000 and managed to squeeze out a punchy 182 horsepower.

8 Nissan SR20DET engine

As far as JDM engines go, Nissan’s SR20DET is limited to quite a tall pedestal. The powerful four-cylinder engine powered several cars such as the Nissan Bluebird, the iconic S15 Silvia and the Nissan Pulsar/Sunny GTI-R, which were among the fastest hot chats of the 80s and 90s. Its 13-year production run couldn’t stop it from carving its way into the hearts of tuners and countless enthusiasts.

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The engine is popular in the tuner scene, with countless spare parts available worldwide. With only 247 horsepower in stock, each mild tuning boosts power to about 270 horsepower; 400 horsepower is achievable on stock internals.

7 Toyota 1UZ-FE engine

It is common to see road car engines turning into racing engines and vice versa. The naturally aspirated 1UZ engine found in several Lexus cars from the 1990s was initially designed as a race engine and then transformed for road use. For a V8 it is lightweight and can happily rev to 8,000 rpm without breaking a sweat.

But like any other engine, the 1UZ comes alive when revved up and can produce over 400 horsepower without a turbo. Twice as much power is achievable with a fully built turbo setup. The pre-94 1UZFE is considered the holy grail tuning variant after Toyota’s changes to the post-94 model; lighter connecting rods, high power and the VVT-i update.

6 Subaru EJ Series Engines (EJ20G)

The EJ series motors are every tuner’s dream for several reasons; their signature four-cylinder boxer (flat) layout, tuning potential and the trademark rumbling exhaust note. The turbocharged EJ20G (nicknamed EJ20T) is the most popular for its racing pedigree. It is considered one of the best JDM engines in the world.

The EJ20T is a durable and reliable powerplant that found its way into the Legacy, Forester and Impreza WRX STI. The latter is the most notable as he has been a standout in the WRC championship for years. The EJ20G was limited to 276 horsepower, but can be tuned to about 500 horsepower or more, with standard internals still intact.

5 Nissan RB Series Engine (RB26)

Nissan’s RB engine brought worldwide fame to the legendary Nissan Skyline. The RB series is a turbo six-cylinder popular in the GT-R family. The three turbo versions (RB20DET, RB25DET and RB26DETT) are every tuner’s dream, but the RB26DETT – used in the R32-R34 Skylines – is the father of them all. It was designed for one reason only; to win races in the Group A Touring Car category.

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The twin-turbo 2.6-liter mill turned a maximum of 276 horsepower. Sounds low by today’s standards, but the tuning potential is unmatched. With a few tweaks, tuners have unlocked ways to coax north of 500 horsepower into the RB26.

4 Nissan VR38 engine

The VR38 follows in the footsteps of its smaller brother, the RB series, as it is easy to tune. The 3.8-liter twin-turbocharged V6 in the Nissan GT-R arrived in 2007 and produced 480 horsepower. Since then it has received several upgrades and the latest model in the GT-3 spec Nissan GT-R NISMO delivers 710 horsepower.

The maximum power milked out of this V6 is over 1,500 horsepower, and it looks like more is coming soon. And if the 3.8 liter displacement isn’t enough for you, there are: aftermarket stroker kits to boost the engine up to 4.6 liters

3 Honda K20 engine

Honda’s K Series has stood the test of time since its introduction in 2001. With its high tuning potential and reliability, it’s easy to see why car enthusiasts are trading their stock engines for the K20. Even the new turbocharged 306 horsepower Type R is equipped with an insanely tunable K20 engine, the K20C1.

For an engine to leave its facility in such a well tuned condition – even naturally aspirated – a lot more power needs to be drawn out of it. Equipping the K20 with 2.6-liter stroker kits and a 2.4-liter K24 bottom allows the engine to crank over 300 horsepower without resorting to forced induction.

2 Toyota 1/2JZGTE engines

The MK IV Supra is a fan favorite among gearboxes, but one thing is certain, it owes its success to the indestructible 2JZ mill under the hood. While it is the Skyline turbocharged RB straight-six that first attracted tuners, the JZ engine is the current favorite among tuning fans.

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The 3.0-litre twin-turbo behemoth produced 276 horsepower while it was stock, but was bumped up to 326 horsepower for other markets. It’s when you downgrade the small turbos and slap a well-specified big turbo on the 2JZ-GTE that things come alive. The engine’s cast iron block can withstand ridiculous horsepower with stock internals, up to 1,200 hp in some cases

1 Mitsubishi 4G63 engine

Mitsubishi enthusiasts called this engine the 2JZ of the four-cylinder world. Built to meet WRC standards, the 4g63 is highly tunable and capable of over 1,000 horsepower. This is made possible by the strong cast iron block and quality sleeves, making the engine bulletproof and reliable enough to handle massive horsepower.

The 2.0-litre turbocharged 4G63T powered the first nine generations of the iconic Lancer Evo. And yes, it’s the same power unit under the hood of the Tommi Makinen Lancer who won four consecutive WRC Championships from 1996 to 1999.