Honda Grom MSX125 (2021+) Maintenance Schedule and Service Intervals
This is the maintenance schedule and associated service intervals for the Honda Grom available from mid 2021 (or 2022 in some areas), replacing the venerable original Honda Grom.
The Honda Grom (MSX125 in Europe and East Asia) is a 125cc compact motorcycle, sharing an engine with other “mini” motorcycles like the Honda Monkey.
Honda updated the Grom for the 2021 (or 2022 in some places). They made it Euro 5 compliant, gave it slightly more power, a much-requested fifth gear, quick-detach body panels, an LCD dash, and an IMU to assist with ABS.
In terms of maintenance, the schedule changed slightly — there’s now a user-serviceable oil filter.
Here are the other Honda miniMOTO maintenance schedules:
- Honda Monkey (2018-2021)
- Honda Super Cub C125
- Honda Grom 2014-2020
- Honda Grom 2021+
- Honda Navi 2016+ (2022+ in the US)
- Honda Trail 125 / CT125 2021+
This was originally published Sep 12, 2021, but has been significantly updated since.
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2021+ Honda Grom Service Intervals
Service intervals are every 4000 mi or 6400 km for the Honda Grom. This is like other motorcycles in the Honda miniMOTO range (which mostly share the same engine).
At each service, don’t just change the oil, but also inspect or replace the spark plug and check the valve clearances.
The Honda Grom 2021 differs from other variants of the miniMOTO range in that it has a user-serviceable oil filter.
Make sure you keep your chain clean and lubed. Despite being small-engined bikes, the Honda Grom is often ridden in conditions that can put a lot of stress on a chain (e.g. getting it dirty or wet, or doing lots of wheelies or racing it), which means you need to pay attention to it.
Luckily, as an air-cooled engine, there’s no liquid coolant to replace in the Honda Grom.
What you need to service your Honda Grom (2021+)
Doing your own service on the Honda Grom is part of the ownership experience. But what oil, spark plugs etc. should you use? Apart from general standard motorcycle maintenance tools, here’s what you need to service your Honda Grom (2021+).
Key change from the earlier Grom is the oil filter. The part used is a common Honda one. But a few other parts are different too, e.g. the spark plug.
| Part | Honda Grom 2021+ Spec |
|---|---|
| Oil | Honda recommends SAE 10W-30 oil that’s API classification SG or higher or JASO T 903 standard MA. There are a lot of oils that fit the bill, but Honda recommends Pro Honda GN4 10W-30. |
| Oil filter | The 2022+ Honda Grom takes an oil filter with part number 15412-MGS-D21, or replace it with a Hiflofiltro HF117. |
| Spark plug | Manual specifies NGK CPR7EA-9S (different to former years). |
| Brake fluid | The manual recommends Honda DOT 4 or DOT 3 brake fluid. |
| Air filter | Honda part number for the air cleaner is 17210-K26-G00 for 2021+ (different to earlier years — new airbox). |
| Chain maintenance | Service your chain regularly! Either use a Motul chain care kit, or with Motul chain paste. |
| Grease | Use lithium soap-based grease and silicone grease for external pivot points, like the sidestand and bearings. |
| Brake pads | EBC FA375HH for the front and FA629HH for the rear (same as former years). |
Honda Grom Maintenance Schedule
Below is the maintenance schedule for the Grom 2021+, re-ordered to be more intuitive, and made more legible.
Notes:
- Keep following this maintenance schedule past the end of the schedule, following the pattern shown every 1, 2, or 3 service intervals
- Break-in service for the Grom is simply to change the oil, check the torque of everything, and adjust engine idle speed.
- Honda suggests getting a qualified mechanic to service wheels/tyres, steering head bearings, and brake fluid.
Maintenance Procedures:
- I: Inspect and clean, adjust, lubricate, or replace, if necessary
- C: Clean
- R: Replace
| x 1000 mi | 4 | 8 | 12 | |
|---|---|---|---|---|
| x 1000 km | 6.4 | 12.8 | 19.2 | Every |
| Engine oil — Replace (Pro Honda GN4 10W-30) | ✓ | ✓ | ✓ | Year, or more often if riding in wet / dusty areas |
| Engine oil strainer screen — Clean | ✓ | |||
| Engine oil filter — Replace (HF117) | ✓ | |||
| Spark plug — Replace (CPR7EA-9S) | ✓ | |||
| Valve clearances — Inspect/Adjust | ✓ | ✓ | ✓ | |
| Air filter — Replace | ✓ | Replace more often if riding in wet / dusty areas | ||
| Brake Fluid (Honda DOT 4) — Replace | 2 years | |||
| Nuts, Bolts, Fasteners — Check, tighten as necessary | ✓ | |||
| Steering Head Bearings — Check, and replace as necessary | ✓ | |||
| Evaporative Emission Control System — Check / Clean | ✓ |
Regular inspection checklist
Below is the list of annual inspection items for the Honda Grom. Do these according to the schedule above.
| Honda Grom 2021+ Inspection Checklist |
|---|
| Brake fluid level — Check |
| Spark plugs — Inspect |
| Fuel Lines — Check condition, correct routing, and for no cracks |
| Throttle operation and free play – Lubricate with Protect all cable life Target free play: 2-4 mm (0.1-0.2 in) |
| Check engine idle speed Target idle speed: 1250 rpm |
| Cooling system — Check for no leaks, and that fans come on |
| Drive chain slider — Check wear level. Replace as necessary |
| Clutch system — Check for correct function, and clutch free play |
| Brake system — Check for proper function |
| Brake disc and pad wear — Check |
| Brake light switch — Check lights come on |
| Wheels/Tires — Check for dents, tire condition, tread depth |
| Suspension — Check for smooth operation, no leaks |
| Headlight aim — Check, re-adjust after adjusting suspension |
| Side stand / Centre stand — Check for smooth function, lubrication condition |
| Steering head bearings — Check for smooth operation |
| Nuts, bolts, fasteners — Check for presence. Replace / retighten as needed |
| Secondary air supply system (if fitted) — Check |
| Crankcase breather (if fitted) — Check, clean as needed Clean more often if riding at full throttle or in rain |
Maintaining Your Chain on the Honda Grom
It’s important to maintain your chain on the Grom, as on any chain-driven motorcycle, but particularly as the Grom is typically subjected to a bit of abuse (and, unfortunately, sometimes neglect). Use a good-quality chain lubricant like Motul chain paste, or a Motul chain care kit which comes with a couple of handy tools to maintain the chain.
Honda recommends you follow the following chain maintenance schedule:
| Chain maintenance item | Every |
|---|---|
| Check drive chain lubrication condition, lubricating if necessary More often if you ride your Grom in dirty, dusty, or wet conditions. Lubricate after cleaning. | 300 mi / 500 km |
| Check drive chain slack, adjusting if necessary See notes below | 300 mi / 500 km |
To check the slack on your Grom, put it in neutral, onto its kickstand, and on a level surface.
Check the slack on the lower part of the chain, midway between the sprockets, and check it in multiple places (move the motorcycle forwards and backwards) as chains wear unevenly.
Slack on the Honda Grom is defined as the free vertical movement of the chain.
Target chain slack for the Honda Grom: 30 – 40 mm (1 3/16 – 1 9/16 in)
If the chain slack is out of spec, you need to adjust it.
Adjusting chain slack
To adjust the chain slack on the 2021+ Grom, follow the steps below. As with measuring chain slack, make sure that the motorcycle is on a level surface on its kickstand, in neutral, with no weight on it (no bags or luggage).
- Loosen the rear axle nut and the lock nuts on both sides of the axle.
- Turn both adjuster nuts to tighten (or loosen) the chain. Keep checking the chain tension to see if it has come within spec.
- Keep an eye on the adjuster alignment marks on either side of the axle. Make sure that the adjustment is to the same point.
- When you’re done, tighten the axle to 59 Nm / 44 lb-ft.
- Re-check the chain slack again to make sure it’s still within spec.
Tyre size and tyre pressure for the Honda Grom
The manual for the Honda Grom specifies these tyre sizes and recommends the following tyre pressures (when cold):
| Tyre | Size | Tyre pressure |
|---|---|---|
| Front | 120/70-12 51L | 29 psi / 2 bar |
| Rear | 130/70-12 56L | 29 psi / 2 bar |
The Honda Grom ships with Vee Rubber V119C or IRC NR77U tyres — tubeless.
About the Honda Grom MSX125 (2021+)
The 2021+ Honda Grom (known as the MSX125 in Europe) continues the same basic concept as the earlier Grom — a fun and high-tech mini-motorcycle that’s a great platform for learning to ride, modify, and stunt motorcycles.
Because its 124cc engine only makes very modest power (7 kW or 9 hp), the Grom isn’t going to get you in a huge amount of trouble unless you really try. Its top speed is somewhere that’s barely freeway legal, and in many parts of the world it’s not legal to ride motorcycles like this on the motorways anyway.
But freeways are not what the Grom is about. The Grom is about making the absolute most out of lower speeds. It’s the kind of bike that is the platform for people to learn how to do things like wheelies and stoppies or how to get their knee down for the first time.
The new-for-2021 (2022 in the US) Grom MSX125 is a huge improvement over previous generations. The engine has been revamped with an undersquare design and higher compression ratio, giving slightly more power and also higher efficiency.
Other important changes for the 2021+ Grom/MSX125 are
- A five-speed transmission — for a bit more efficiency at higher speeds
- A revised LCD dash, with a tachometer, fuel gauge, and gear position indicator
- Bodywork that’s quick to remove
- Improved engine (higher compression ratio, more power, more efficiency)
As usual, the Honda Grom comes in a variety of awesome colours, including black, silver, and red. I mean Gunpowder Black, Force Silver, and Gayety Red.
The Honda Grom is, sadly, being discontinued in some markets for economic or emissions reasons. But those who want a cute and cheaper alternative can look at the CFMOTO XO Papio (a.k.a. the Papio SS / CL).
Manual for the Honda Grom (2021+).
The above maintenance schedule comes directly from the user’s manual for the 2022 Honda Grom in the US. It’s slightly different to the schedule in earlier manuals.
You can download it here.
