2024 what's with the engine tweaks?

[Chinjab]

I understand that for the 2023 and 2024 models they have made some moderate engine modifications.

The documentation seems to indicate that it was about creating more low end torque for off road riding.

However, from what I have read, seems like the real reason is emissions control regulations.

I can't really find any real life comparisons (blogs, videos) between the pre '23 engines and the latter ones.

Are they actually different? Could one notice the difference when riding on or off road?

Was wondering if anyone had any insight regarding this...

 

[dmonkey]

@bryanchurch06 has owned both and shared his observation here:

22 to 23 difference in ride

I rode the 23 model yesterday about 2 miles around the rv Park due to muddy roads outside park. I know this is subjective and hard to quantity but the 23 model feels much smoother than the 22 was, the gear changes are like butter on it where as the 22 was always a little clunky no matter how I...

hondatrail125.com

The engine changes were reportedly to meet the Euro 5 emissions standard, which is more strict in most ways than North American emission requirements. Many countries outside Europe base their emissions on Euro standards as well, including Japan, so for building a vehicle for multiple markets it's often used as the global standard. All of the North American market 125cc mini motos got the same engine update with slight variations of manual/semi-auto clutch and 4-speed/5-speed, so the change was not specific to off-road riding or the Trail 125. The redesign also let Honda consolidate parts, as the bottom end is now (mostly) in common with the 110cc mini motos that are popular in Asian markets, and the CRF110.

Here's what Honda published about the engine update, specific to the USA market Trail 125:
ENGINE / DRIVETRAIN
For 2023, the Trail125 gets the 124cc air-cooled, two-valve, overhead-camshaft, four-stroke, single-cylinder engine that the Super Cub received in 2022. Efficient, quiet, fuel-efficient and durable, the engine combines the bottom end (with redesigned crankcases) from the Japanese-market C110 with the SOHC, two-valve top end of the Grom. The engine produces useable, enjoyable power all the way through the rev range, while still offering impressive fuel economy.

Compared to its predecessor, the 2023 Trail125 is more undersquare, with a 50.0mm bore and a 63.1mm stroke, and compression ratio is 10.0:1. State-of-the-art programmed fuel injection (PGM-FI) has automatic enrichment and electronic ignition, ensuring trouble-free starting and efficient operation in every conceivable condition.

Compared to the Super Cub, the Trail125 has a longer intake and tuned exhaust for enhanced low- and midrange power, as well as a three-tooth-larger rear sprocket (38 teeth) for lower gearing—all changes that are ideal for trekking and touring on forest-service roads and trails. The airbox is designed to match the engine. It smooths airflow on the clean side of the panel-type, wet-paper filter (which has a 10,000-mile life in normal riding conditions) and—along with the connecting tube and injector position—improves driveability. Many Trail125 owners prefer to do their own maintenance, and a welcome feature is a replaceable oil filter.

While the outward appearance of the muffler (one element of the Trail125’s “mythology”) stays the same, the internals are modernized; with the gain in combustion efficiency, a single, more efficient catalyzer replaces the pair of catalyzers used with the previous exhaust. The ECU programming maximizes performance and efficiency, and the alternator output has been increased.

As before, the transmission has four speeds (with neutral at the bottom), and in true Trail125 tradition, it’s operated via an automatic centrifugal clutch, eliminating the need for a clutch lever. At standstill, the rider simply selects the gear required with the left foot lever; as the throttle is opened, the clutch operates automatically, and it continues to do so through each ratio change, up or down. A helical primary gear reduces mechanical noise. For optimum shift feel and reduced shift noise, the engine has a high-quality shift-drum bearing, shift-arm rubber, and optimized clutch-damper rubber material.

This video shows the manual clutch engines that went from a 4-speed to a 5-speed, but talks through some of the other changes that are relevant to the base engine design as well:

 

[Chinjab]

Super helpful! Thank you for the detailed explanations! Much appreciated.

 

[Flash]

My 2024 hax the two catylic one up frong in verticle section and another inside the muffler. A real restricted flow. I junked it for a used Harley Sportster muffler, sacrificing some of the internals and tab mounts. It sounds good and breaths well.