Monkey 125, differences between current and old models
The Monkey 125 that appeared in 2018 is the old model (JB02) with a 4-speed transmission, bore diameter Φ52.4mm x stroke length 57.9mm. The Monkey 125 that appeared in 2021 is categorized as the current model (JB03 and JB05) with a 5-speed transmission, bore diameter Φ50.0mm x stroke length 63.1mm.
The following OVER mufflers are all compatible with the current models (JB03 and JB05). Owners of the older model (JB02) should choose the muffler for JB02, not the one for JB03 & JB05.
| type | Release date | Model | mission | Bore diameter x stroke length | Compatible with the following mufflers |
| Current model | July 2024 | 8BJ-JB05 | 5-speed | Φ50.0mm×63.1mm | 〇 |
| Current model | September 2021 | 2BJ-JB03 | 5-speed | Φ50.0mm×63.1mm | 〇 |
| Old model | April 2018 | 2BJ-JB02 | 4-speed | Φ52.4mm×57.9mm | × |
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Stainless steel oval up muffler… 81,400 yen (tax included)
Part number: 16-014-01 Compatible models: Monkey 125 (21-23) (24-)
Inheriting the image of the previous model “JB02 (4-speed transmission vehicle)”, it adopts the most authentic oval-shaped up-type silencer in the Monkey 125 series. The muffler is made of rust-resistant stainless steel.
By optimizing the exhaust pipe layout for the current JB03/JB05 model, the pipe length has been increased, resulting in more torqueful output characteristics in the low speed range. Combined with the compatibility with the 5-speed transmission, it supports stable acceleration when starting, making it the perfect bike for city touring.

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| Stainless steel exhaust pipe | Φ35-Φ50.8 |
| Stainless steel silencer | Oval L=220mm |
| Silencer insertion diameter | Φ50.8 |
| Exterior | Aluminum heat guard |
| weight | – |
| volume | 86dB (proximity) / 77dB (acceleration) |
| Use on public roads | Government-certified muffler (compatible with 8BJ-JB03/JB05 models) |
| Regulations/Responses | Compliant with 2010 noise regulations and 2020 exhaust gas regulations |
| Drain bolt | 〇 |
| Filter | 〇 |
*When using in combination with OVER side covers, please purchase part number: 57-012-01L.
TT-Formula full titanium up muffler… 106,700 yen (tax included)
Part number: 16-014-07 Compatible models: Monkey 125 (21-23) (24-)
The popular “TT-Formula Full Titanium Up” for the previous model “JB02 (4-speed transmission vehicle)” is now available for the current Monkey. While maintaining the original image, the sporty TT-Formula silencer creates a style that is rich in originality.
The volume is set louder than the previous model. In addition to the flat output characteristics in the low and mid-speed range, the peak power and extension in the high rotation range have been greatly improved. Also, compared to the stock, the weight has been significantly reduced to improve operability. This is a high-quality bike that lives up to the Monkey 125’s catchphrase, “You’ll want to ride forever. You’ll be satisfied every time you ride.”

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| Titanium exhaust pipe | Φ35-Φ50.8 |
| Titanium silencer | TT-Formula L=250mm |
| Silencer insertion diameter | Φ52 |
| Exterior | Aluminum heat guard |
| weight | – |
| volume | 86dB (proximity) / 77dB (acceleration) |
| Use on public roads | Government-certified muffler (compatible with 8BJ-JB03/JB05 models) |
| Regulations/Responses | Compliant with 2010 noise regulations and 2020 exhaust gas regulations |
| Drain bolt | 〇 |
| Filter | 〇 |
*When using in combination with OVER side covers, please purchase part number: 57-012-01L.
GP-PERFORMANCE Full Titanium …… 86,900 yen (tax included)
Part number: 16-014-25 Compatible models: Monkey 125 (21-23) (24-)
This down-type muffler is made entirely of titanium for significant weight reduction, and provides torque at low speeds and power at high speeds, making it ideal for a variety of situations, from sporty driving to city driving.
The punchy bass sound resonates comfortably with the rider and lifts their spirits. With its light and powerful ride, it is designed to give the rider a sense of the fun and exhilaration of the Monkey 125.



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| Titanium exhaust pipe | Φ35-Φ50.8 |
| Titanium silencer | GP-Performance L=300mm |
| Silencer insertion diameter | Φ52 |
| Exterior | – |
| weight | – |
| volume | 83dB (proximity) / 77dB (acceleration) |
| Use on public roads | Government-certified muffler (compatible with 8BJ-JB03/JB05 models) |
| Regulations/Responses | Compliant with 2010 noise regulations and 2020 exhaust gas regulations |
| Drain bolt | 〇 |
| Filter | 〇 |
TT-Formula RS Full Titanium …… 94,600 yen (tax included)
Part number: 16-014-50 Compatible vehicles: Monkey 125 (21-23) (24-)
The down-type TT-Formula RS follows the design of the previous model. It retains its sporty impression with a silencer shaped to increase the banking angle, while delivering performance that matches the current JB03 and JB05 models.
The torque that is exerted from the low speed range creates a pleasant feeling of acceleration, and the muffler is designed to be fun to rev, whether riding around town or on winding roads. The sound that emphasizes the bass is pleasant, and it will lift the rider’s spirits as they ride, making for a quality that will make riding even more enjoyable.


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| Titanium exhaust pipe | Φ35-Φ50.8 |
| Titanium silencer | TT-Formula RS L=300mm |
| Silencer insertion diameter | Φ52 |
| Exterior | – |
| weight | – |
| volume | 82dB (proximity) / 78dB (acceleration) |
| Use on public roads | Government-certified muffler (compatible with 8BJ-JB03/JB05 models) |
| Regulations/Responses | Compliant with 2010 noise regulations and 2020 exhaust gas regulations |
| Drain bolt | 〇 |
| Filter | 〇 |
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The Monkey 125 is actually a touring bike. With a completely redesigned engine, it has evolved for stress-free riding!
[Announced in Europe] Honda Monkey 125 gets new engine and upgrades from 4 to 5 speeds. | Motor-Fan Bikes
The exhaust system weighs less than half the stock weight (approximately 5.2 kg)! OVER Racing’s Honda Monkey 125 customization | Tokyo Motorcycle Show 2022
Is an aluminum frame on a Monkey 125 too much? | Osaka/Tokyo Motorcycle Show 2023
























