Honda Grom mods & upgrades
No bike in the US gets modified at a higher rate per dollar than the Grom — it is the platform where riders learn to wrench.
- Engine124 cc air-cooled single
- Power~9.7 hp (claimed)
- Wet weight223 lb (claimed, 2022+)
- Seat height30.0 in
- Gearbox4-speed (2014–2020) · 5-speed (2022+)
Parts that fit the Grom
59 parts in 13 categories, with typical prices — verify fitment for your exact year and market.
| Part | Tier | Typical price | Fitment | Add to sheet |
|---|---|---|---|---|
| Exhaust2 fitYoshimura, Two Brothers, Hindle and Tyga all make Grom systems — almost all are full systems, and every one is generation-specific (4-speed vs 5-speed headers differ). Loud is easy on 9.7 hp; pair any pipe with fueling to actually run right. | ||||
| Akrapovič slip-on (titanium) | premium | $1,000 | fits: verified · 2021+ | Add to sheet |
| Toce Razor Tip full system | mid | $1,200 | fits: verified · 2014–20 & 2022+T-Slash system | Add to sheet |
| Tune6 fitEJK piggyback controllers handle bolt-on fueling; the aRacer standalone ECU is the built-Grom standard, with autotune and support for big-bore setups. Stock ECU plus big bore equals lean — budget fuel management into any engine build. | ||||
| Woolich Racing flash kit + license | premium | $500 | fits: verified · 2013–25 | Add to sheet |
| Sprint Filter P08 air filter | premium | $120 | fits: verifiedGrom 2014–19 (PM180S) and 2021+ (SM224S); 2020 not listed | Add to sheet |
| Dynojet Power Commander 6 | mid | $480 | fits: verified · 2014–15 & 2017–262021+ unit: check the crank sensor is on the alternator harness; not 2016 | Add to sheet |
| Moore Mafia mail-in ECU flash | mid | $340 | fits: verified · 2013–15 | Add to sheet |
| DNA performance air filter | mid | $110 | fits: verifiedGrom 2014–20 (P-H1N13-01); 2021–26 is a Stage 2 filter (P-H1N25-S2, re-tune needed) | Add to sheet |
| K&N high-flow air filter | budget | $95 | fits: reportedGrom 2014–20 (HA-1313) and 2022–26 (HA-1222); 2021 not listed | Add to sheet |
| Suspension6 fitYSS shocks are the budget classic, Öhlins the premium pick, and minimoto specialists carry fork springs and internals. An adult at speed is far outside the stock suspension's design brief — this matters more than engine work. | ||||
| GPR V5-S steering stabilizer | premium | $530 | fits: verified · 2013–20 & 2022+2021 not listed | Add to sheet |
| Nitron R1 rear shock | mid | $810 | fits: verifiedGrom 2014–20; 2021–24 only as Nitron's separate '35mm' kit | Add to sheet |
| YSS rear shock | budget | $500 | fits: verified · 2013–22 & 2023+Grom/MSX125 2013–22 and 2023+ | Add to sheet |
| Race Tech Gold Valve kit | budget | $300 | fits: verified · 2014–21Cartridge kit | Add to sheet |
| HyperPro progressive fork springs | budget | $200 | fits: verified · 2013–25 | Add to sheet |
| Race Tech fork springs | budget | $150 | fits: verified · 2014–212022+ not listed | Add to sheet |
| Brakes7 fit | ||||
| Galfer Wave front rotor pair | premium | $620 | fits: verified · 2013+Single rotor | Add to sheet |
| Spiegler stainless front and rear brake line kit | premium | $250 | fits: verifiedGrom 2014+ (non-ABS kit); ABS 2022–24 (ABS kit) | Add to sheet |
| Core Moto custom stainless brake lines | mid | $150 | fits: verified · 2014–25Non-ABS | Add to sheet |
| Spiegler stainless front brake line kit | mid | $130 | fits: verified · 2014+ABS 2022–24 needs the front and rear kit | Add to sheet |
| GBrakes (formerly Galfer USA) stainless front brake line kit | mid | $100 | fits: verified · 2014–20Front kit; 2021+ not listed | Add to sheet |
| EBC Double-H sintered pads (per caliper) | budget | $50 | fits: verified · 2014+FA375HH | Add to sheet |
| Motul RBF 600 racing brake fluid | budget | $25 eBay — $24.99 checked Oct 14 (opens in new tab) | fits: verifiedNon-silicone synthetic racing brake fluid for hydraulic brake and clutch systems; exceeds DOT 3 and 5.1. | Add to sheet |
| Tires & Wheelsnone listed yetStreet: stock-size sport rubber is limited but adequate for 9.7 hp. Race: PMT slicks and Mitas race compounds in 12-inch sizes are the grid standards — sourced from minimoto specialty shops rather than big retailers. | ||||
| Nothing listed for this bike yet | ||||
| Levers8 fitShorty levers fit the Grom's small controls well; the usual ASV/CRG quality argument applies at Grom prices — budget pairs are common and the risk is lower at these speeds. | ||||
| ASV C5 folding lever pair | premium | $300 | fits: verified · 2014–26 | Add to sheet |
| Gilles Tooling FXL adjustable lever pair | premium | $260 | fits: verified · 2022+Not 2014–21 | Add to sheet |
| Puig 3.0 lever pair | premium | $240 | fits: verified · 2014–25 | Add to sheet |
| Bonamici EVO brake lever guard | premium | $230 eBay — $258.30 checked Oct 14 (opens in new tab) | fits: reportedSold without adapter; needs a Bonamici adapter chosen by bar-end inner diameter (13–21 mm) or by bike | Add to sheet |
| CRG RC2 lever pair | premium | $220 | fits: reported · 2014–26 | Add to sheet |
| Pazzo shorty lever pair | mid | $200 | fits: verified · 2014–25 | Add to sheet |
| Womet-Tech Evos shorty lever pair | budget | $110 | fits: verified · 2014–20Not 2022+ | Add to sheet |
| R&G moulded lever guard | budget | $70 | fits: verified · 2014+MLG0013 | Add to sheet |
| Rearsets2 fitSeat: Aftermarket flat and comfort seats address the stock plank; gen 3's flatter seat reduced the need. Stunt and race seats change mounting by generation. | ||||
| Sato Racing rearsets | premium | $600 | fits: verified · 2013–20 & 2022+ | Add to sheet |
| Woodcraft complete rearset kit | mid | $530 | fits: verified · 2014–20 & 2022+ | Add to sheet |
| Clip-ons & Throttle3 fit | ||||
| Motion Pro Rev3 throttle kit | mid | $190 | fits: verified · 2014–15 & 2017–20Grom (MSX125) 2014–15 and 2017–20 (2016 not listed) | Add to sheet |
| Domino A450 race grips | budget | $30 eBay — $29.95 checked Oct 14 (opens in new tab) | fits: verifiedUniversal 22 mm (7/8 in) open-end race grips, 120–125 mm, for twist throttles | Add to sheet |
| ProGrip 717 grips | budget | $18 eBay — $17.98 checked Oct 14 (opens in new tab) | fits: verifiedUniversal open-end race grip, 122 mm long, fits 22-25 mm bars; the RA version is 125 mm | Add to sheet |
| Crash Protection4 fitT-Rex Racing cages and sliders are the Grom staples, with case protection for race grids. Gen-specific — a JC75 cage does not bolt to a JC92. | ||||
| R&G engine case cover kit | mid | $220 | fits: verified · 2021–24Race kit only; 2025+ not covered | Add to sheet |
| R&G Aero frame sliders | mid | $140 | fits: verified · 2016+2016–20 kit and 2021+ kit; 2014–15 not covered | Add to sheet |
| R&G fork protectors | budget | $60 | fits: verified · 2014+Kit is for the MSX125/Grom 125 | Add to sheet |
| R&G bar end sliders | budget | $55 | fits: verified · 2014+Kit is for the MSX125/Grom 125 | Add to sheet |
| Tail Tidy & Billet7 fitTST Industries owns the Grom lighting niche: fender eliminators, integrated tails, flush signals, all gen-specific and plug-and-play. | ||||
| New Rage Cycles fender eliminator | mid | $180 | fits: verified · 2014+Kits for 2014–20 and 2021+ | Add to sheet |
| R&G tail tidy | mid | $160 | fits: verified · 2014+Kits for 2013–15, 2016–20 and 2021+; sold as MSX125 | Add to sheet |
| TST LED integrated tail light | mid | $140 | fits: verified · 2014–20 & 2022+Separate kits for 2013–20 and 2022+ | Add to sheet |
| Competition Werkes fender eliminator | mid | $120 | fits: verified · 2014–202022+ not covered | Add to sheet |
| TST Elite-1 fender eliminator | mid | $85 | fits: verified · 2022+Older Groms use TST's non-Elite kits | Add to sheet |
| Motodynamic sequential LED tail light | budget | $110 | fits: verified · 2014–26Kits for 2014–20 and 2022–26 | Add to sheet |
| TST LED flushmount front signals | budget | $20 | fits: verified · 2014+Kit covers 2013–16, 2017–20, 2022–24 and 2025+ | Add to sheet |
| Bodywork3 fit | ||||
| MRA race windscreen | mid | $140 | fits: verified · 2013–15Grom gen 1 only: MSX125 2013–15 (not 2016+) | Add to sheet |
| TechSpec Snake Skin tank grips | budget | $80 | fits: reported · 2014–26Kits for 2014–15 and 2016–26 | Add to sheet |
| Stompgrip tank grip kit | budget | $65 | fits: verified · 2014–15 & 2017–24Not 2016 or 2025+ | Add to sheet |
| Quickshifter2 fit | ||||
| Healtech iQSE quickshifter (with harness) | mid | $370 | fits: verified · 2014–26Grom / MSX125 2014–26 (QSH-P2T) | Add to sheet |
| Annitori QS PRO 3 quickshifter | mid | $240 | fits: verifiedNeeds rearsets with a shift rod; no year limit given | Add to sheet |
| Drivetrain2 fit420 chain and cheap sprockets make gearing experiments nearly free. Street riders typically add rear teeth for punch; racers carry multiple sprockets per track. The most-changed part on any Grom. | ||||
| Superlite steel rear sprocket | mid | $60 | fits: verified · 2014–20 & 2022–25RS7 steel, 420 or 428 | Add to sheet |
| Vortex steel front sprocket | budget | $35 | fits: reported · 2014–20 & 2022–24420 pitch | Add to sheet |
| Electronics7 fit | ||||
| AiM MXS Strada race dash | premium | $1,400 | fits: reportedUniversal dash; kits ship with a 14-pin CAN or OBD CAN+K harness; AiM claims 2,000+ supported ECUs | Add to sheet |
| AiM Solo 2 DL lap timer | premium | $850 eBay — $899.00 checked Oct 14 (opens in new tab) | fits: reportedUniversal GPS lap timer; the DL adds ECU logging via CAN/RS232/K-line; dedicated bike kits available | Add to sheet |
| Antigravity RE-START lithium battery | premium | $220 | fits: verified · 2014–24ATZ7 RE-START | Add to sheet |
| AiM Solo 2 lap timer | mid | $480 eBay — $499.00 checked Oct 14 (opens in new tab) | fits: verifiedUniversal GPS lap timer; no ECU connection | Add to sheet |
| Starlane Stealth-5 lap timer | mid | $460 eBay — $465.40 checked Oct 14 (opens in new tab) | fits: verifiedWires to the bike's 12 V battery (cable supplied) or an optional battery case; mounts included | Add to sheet |
| Shorai LFM lithium battery | mid | $180 | fits: verified · 2014–24LFM09L2-LC12; check height and clearance | Add to sheet |
| Healtech Brake Light Pro flasher module | mid | $65 | fits: verified · 2013–26BLP-U01 | Add to sheet |
Some links may earn Unstocked a commission at no cost to you. Prices shown are typical street prices — always verify fitment and price at the retailer. Model-specific parts (exhausts, rearsets, bodywork) can run 2–3× between bikes — the sheet shows a typical figure.
What the Grom runs stock
| Part | What it came with | Years |
|---|---|---|
| Suspension | 31 mm inverted fork 3.9 in travel; single rear shock on a steel box-section swingarm, 4.1 in travel; no adjusters listed on any generation | All years |
| Brakes | 220 mm front disc, hydraulic dual-piston caliper rear 190 mm disc with single-piston caliper, all generations | All years |
| Brakes | ABS (Grom ABS / Grom125A trim) IMU-controlled ABS on the ABS trim from the 2022 redesign; the base Grom stays non-ABS | 2022–present |
| Tires & Wheels | 120/70-12 · 130/70-12 12-inch cast wheels (MT2.5 × 12 rims per the European sheet) | All years |
| Drivetrain | 4-speed gearbox chain final drive; 225 lb curb (2014), 229 lb (2017) | 2014–2016 · 2017–2020 |
| Drivetrain | 5-speed gearbox, 15T/38T chain fifth gear added with the 2022 redesign; 223 lb curb (225 lb ABS) | 2022–present |
| Electronics | no rider aids no traction control, ride modes or ride-by-wire on any Grom; ABS only on the 2022+ ABS trim | All years |
From the manufacturers' press material; entries marked reported come from other sources. Check against your exact model year. Stock parts for every bike →
Why mod a Grom
No bike in the US gets modified at a higher rate per dollar than the Grom — it is the platform where riders learn to wrench, race minimoto grids, and try everything because parts cost pocket money next to big-bike prices. Nothing about a Grom stays stock, and Honda leaned into it with quick-release panels on the current bike.
Grom street mods, in order
Clean up the tail
Fender eliminator with an integrated tail light — TST Industries is the Grom lighting standard, with gen-specific kits.
Cage it or slide it
Frame sliders or a full crash cage (T-Rex Racing is the Grom staple). Groms live hard lives; protection first is the community rule here too.
Exhaust plus fueling
On a Grom the 'slip-on' is usually a full system with header — Yoshimura, Two Brothers, Hindle, Tyga. Pair it with fuel management (EJK piggyback at minimum); the tiny single runs lean with an open pipe.
Gearing for grins
A rear sprocket change on the 420 chain transforms around-town punch for the price of dinner. The cheapest personality change in motorcycling.
Suspension that keeps up
The stock shock and fork are built to a price: a YSS shock is the budget classic, Öhlins the serious pick, with fork springs or cartridge internals from minimoto specialists.
Seat and contact points
Aftermarket seats fix the stock plank on long rides; grips and levers finish the fit. Gen 3's flatter stock seat already helps.
Grom track build, in order
Race rubber on 12s
12-inch race tires — PMT slicks and Mitas race compounds are the minimoto grid standards. Street IRC stockers are the single biggest lap-time limiter.
Suspension for your weight
Adult riders overwhelm the stock setup instantly: shock upgrade plus fork springs or internals, set for rider weight. This is the first real money a race Grom needs.
Controls that fit a crouch
Rearsets from the minimoto specialists solve peg-folding lean angles; shorty levers and grippy pegs finish it.
Make it crash-able
Case covers or a cage, plus race bodywork — gen 3's quick-release panels make glass swaps trivially fast between sessions.
Engine — where classes allow
Big-bore kits (Takegawa and Kitaco are the trusted Japanese names) with an aRacer standalone ECU are half the fun of Grom racing — but check your class displacement rules first, and never bore it without fueling.
Gearing per track
Minimoto tracks are tight; carry two or three rear sprockets and match the 420 gearing per layout. Racers change these like tire warmers.
Grom fitment by year (JC61 (gen 1), JC75 (gen 2), JC92 (gen 3))
- JC61 (gen 1)2014–2016
US launch of the global MSX125. Air-cooled 125 single, 4-speed box. The frame code (JC61) matters — Japanese kit makers list fitment by it.
- JC75 (gen 2)2017–2020
Restyle with LED headlight and sharper panels. Same 4-speed engine family as gen 1 — engine parts largely cross, bodywork does not. No 2021 US model year.
- JC92 (gen 3)2022–present
New 5-speed engine, higher compression, flatter seat, quick-release body panels made for swapping. Engine and exhaust parts do not cross from the 4-speed bikes. SP editions add color, not fitment changes.
Grom gotchas — read before buying
Grom parts interchange
Reported by riders; verify before buying. Full chart →
- Community-reported: the Honda Monkey 125 shares the Grom's engine generation-for-generation (4-speed through 2021, 5-speed from 2022) — many engine and drivetrain parts cross between them.
- Global-market MSX125 parts fit the matching-generation US Grom (community-reported) — the bikes are the same machine under different names, which widens the used-parts pool considerably.
Honda Grom mods FAQ
Will 2014–2020 Grom parts fit a 2022+ Grom?
Bodywork, cages and lighting: no — and engine parts absolutely not. The 2022+ bike has a new 5-speed engine that shares no big-bore kits, headers or clutch parts with the older 4-speed. Check the frame code (JC61/JC75/JC92) on every listing.
Do I need a tune after an exhaust on a Grom?
You should plan fueling with any full system — which is what most Grom exhausts are. An EJK piggyback covers bolt-ons; an aRacer ECU is the standard once a big bore enters the picture. The lean-running stock map is not kind to open pipes.
How much faster can you make a Grom?
Meaningfully, by Grom standards: gearing and a pipe change how it feels, and big-bore kits with proper fueling change what it is. No dyno claims here — but the minimoto race grids prove the platform takes serious building.
Can you race a Grom?
Yes — Groms fill minimoto and mini-roadracing grids across the US, including youth and adult classes. Race prep is cheap relative to big bikes: tires, suspension for your weight, protection, and gearing get you on grid.