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Suzuki RM 125 Parts

By AS3 Performance

The Suzuki RM 125 is one of the longest-running and most loved 125cc two-stroke motocross bikes ever made, produced from 1975 right through to 2008. Even after Suzuki discontinued it, the RM 125 remains popular in the classic and twin-shock scenes, club-level 125cc two-stroke racing, and as a project bike. At AS3 Performance we stock a wide range of parts for the RM 125 from the late-70s models to the final 2008 bike.

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Which Parts Are Most Popular For The Suzuki RM 125?

At AS3 Performance we stock a wide range of aftermarket parts for the Suzuki RM 125, from the late-70s evolution models all the way to the final 2008 production bike. Our range covers braided brake lines, silicone radiator hoses, power valve covers, gasket kits and throttle cables, just a small example of what we offer for the RM 125, all designed and tested for this bike specifically. Whether you're rebuilding a project bike, replacing a part that has come to the end of its life, or upgrading the bike for an edge in classic motocross events, you should find what you need in this category.

Brake Lines

The OEM rubber brake lines on the RM 125 perish with age, and on a 30-plus-year-old bike they have almost certainly hardened, swelled or developed soft spots. A perished line gives a vague, spongy feel at the lever and in the worst case can burst under pressure. Our AS3 Performance by Venhill braided brake lines are manufactured from marine-grade stainless steel braiding over a DuPont PTFE inner core, factory tested to 1500 psi and DOT/TUV approved. The braided construction eliminates expansion, giving a firmer, more consistent feel and a more direct brake action.

We supply both front and rear brake lines for the RM 125 across most of its production history:

  • Front Brake Lines — fitments stretching from the introduction of the hydraulic front brake in 1985 to the last year of production in 2008. Available in black and yellow.
  • Rear Brake Lines — from 1989 to 2008, some also compatible with the RM 250. Available in black, yellow or red depending on the year.

Each line is fitted with stainless steel swivel unions which help achieve perfect banjo alignment at the caliper and master cylinder, and is supplied with 5 copper washers.

Silicone Hoses

The OEM rubber radiator hoses will have hardened and perished decades ago on most bikes. Our silicone radiator hose kits are manufactured from high-quality 3-ply silicone with polyester reinforcement and a 4.5mm wall thickness, pressure tested to five times the standard working pressure, and far less vulnerable to puncture, perishing or impact damage than rubber. They also restore the look of a well-maintained bike with crisp colour-matched hoses.

We supply silicone hoses for almost all liquid-cooled RM 125 models. A quick overview of the colour options by year:

  • RM 125 (1986–1990) — black, blue or yellow
  • RM 125 (1991) — black, blue, red or yellow
  • RM 125 (1992–1995) — black, blue, red or yellow
  • RM 125 (1996–2000) — black, blue, red or yellow
  • RM 125 (2001–2008) — black, blue, red, yellow or white

When installing silicone hoses we always recommend using hose clips with smooth inners and edges so as not to damage the hoses. We supply a stainless steel hose clip kit for each of our silicone hoses, with a link to the correct clip kit at the bottom of each product description.

Power Valve Covers

The exhaust power valve on the RM 125 (Suzuki's AETC system) sits on the right side of the cylinder and is exposed to roost and rocks thrown up at the front of the bike. The OEM cover is functional but is cast aluminium and can get damaged or discoloured over time. Our AS3 Performance power valve cover is a billet aluminium replacement that bolts directly in place of the OEM cover, finished in anodised black or yellow with AS3 Performance branding. It fits the 1991–2008 RM 125 and is compatible with the original gasket and mounting bolts.

Gasket Kits

A complete engine gasket kit is essential for any RM 125 rebuild, top-end refresh or major engine work. Our AS3 Engine Gasket Kits include everything needed for a full strip and rebuild, including head gasket, base gasket, cylinder gaskets, clutch cover gaskets and the smaller seals throughout the engine, all manufactured to OEM specifications. We stock kits to cover the most common generations:

Always check the year on the individual product page to confirm fitment, as Suzuki revised the engine multiple times across the bike's production run and the gasket sets are model-year specific.

Throttle Cables

The OEM throttle cable on the RM 125 will have stretched, kinked or seized in many cases by now, and a sticky throttle on a 125cc two-stroke is the kind of thing that ruins a moto. Our AS3 Performance by Venhill Featherlight throttle cables are direct OEM replacements built to higher tolerances than the factory cables, with a low-friction inner lining for a smoother, lighter throttle action and a longer service life. Available in black or yellow across the full RM 125 production history. Use the year filter on the product page to find the cable that fits your specific bike.

What Parts Offer The Most Protection For The Suzuki RM 125?

Clutch & Ignition Covers — Parts for the RM 125 are becoming harder to obtain as Suzuki discontinue them, and clutch and ignition covers fall into this category. We provide billet aluminium clutch and ignition covers for the RM 125 which are both compatible and much stronger than the OEM parts.

Rear Brake Caliper Guards — The standard rear brake caliper guards on the RM 125 are plastic and can crack, get damaged or become worn over time. Upgrading to one of our billet aluminium guards provides better protection to the braking system and gives the bike a fresh look.

Rotating Bar Clamps — A simple part that can easily save the end of a race or an expensive repair to the front brake area. AS3 Performance rotating bar clamps install on the back of the master cylinder and feature a plastic sleeve that lets the master cylinder rotate on impact in the event of a crash or tip over.

About The Suzuki RM 125

The Suzuki RM 125 was Suzuki's flagship 125cc two-stroke motocross bike from 1975 through to 2008, when Suzuki discontinued the model in favour of the four-stroke RM-Z 250 in the small-displacement classes. Across that 33-year run the bike went through multiple major redesigns and was raced at world championship level by some of the most successful 125cc riders of the era, including Travis Pastrana and Brian Deegan.

The engine is a 124cc liquid-cooled two-stroke single, originally with a piston-port intake and later with a reed-valve intake. From the early 1990s the bike was fitted with Suzuki's AETC exhaust valve system, which varies exhaust port timing with engine speed to broaden the powerband. The bike runs a Mikuni carburettor, a 6-speed gearbox and a multi-disc wet clutch.

The chassis went through several major changes. The 1980s and 1990s bikes used a steel double-cradle frame; from 2001 onwards Suzuki fitted an aluminium twin-spar frame, a major weight reduction and chassis improvement. Front suspension is a Showa or Kayaba telescopic fork depending on year, with a Showa rear shock and rising-rate linkage. Brakes are hydraulic discs front and rear, with Nissin calipers on most years. Wheels are 21-inch front and 19-inch rear.

The RM 125 has had multiple generations of bodywork, graphics and detail changes through its life, and the parts we stock cover most year ranges, with separate fitments per generation where the bike's components changed. Always check the year on the individual product page before purchasing.

Suzuki RM 125 Parts FAQs

Which colour radiator hoses best suit the Suzuki RM 125?

This depends heavily on the era of the bike. Over the years Suzuki changed the colours of the frame and graphics on the RM 125, and on the earliest models even the engine casings were a different colour to the modern bikes. Yellow is always a favourite as it matches the plastics across the whole year range. If you want something more subtle, blue hoses suit the earlier models which had a blue frame, and on some later models Suzuki used red in the graphics, which a red set of hoses will complement perfectly.

What's the difference between the AS3 Featherlight throttle cable and the OEM cable?

The Venhill Featherlight cable uses a low-friction inner lining and tighter manufacturing tolerances than the OEM Suzuki cable, giving a noticeably smoother and lighter throttle action and a much longer service life in dusty conditions. The cables are direct OEM replacements that use the original routing and adjusters, so no modifications are required to fit one.

Do you stock parts for older RM 125 models from the 1970s and 1980s?

Yes. Our range goes back to the 1976–1980 RM 125 for clutch cables and front brake cables, and 1979–1986 for rear wheel bearing kits. The brake lines, silicone hoses and gasket kits cover the bike from the mid-1980s onwards. Use the year filter on the product page to find parts compatible with your specific bike.

What does the AETC power valve actually do, and does the AS3 cover affect it?

The AETC (Automatic Exhaust Timing Control) is Suzuki's exhaust power valve system. It sits in the exhaust port and varies the effective port height with engine speed, opening at higher RPM for a stronger top end and closing at lower RPM for cleaner low-speed running. Our AS3 power valve cover is a direct OEM replacement for the cover over the AETC mechanism on the right side of the cylinder. It does not affect how the valve operates; it simply protects the mechanism from roost and impact and gives a tidier finish than the OEM cover.

Are the gasket kits suitable for a full engine rebuild?

Yes. The AS3 Complete Engine Gasket Kit Sets include all the gaskets and seals needed for a full strip and rebuild, including the head gasket, base gasket, cylinder gaskets, clutch cover gaskets and the smaller seals throughout the engine. Match the kit to your specific year of bike using the product page filter, as Suzuki revised the engine internals multiple times during the RM 125's production.

Can I still get a complete OEM-style restoration of an older RM 125?

For most components yes. As well as coloured options we supply the majority of our parts in black, or occasionally silver depending on the product, for a more OEM-style look. These include cables, brake lines, levers and our wide range of anodised accessories. For OEM bodywork and graphics you would need a specialist restorer, but many of the parts and accessories can be sourced through us. Get in touch if you have a specific project in mind and we can help you put together a parts list.

Are the AS3 RM 125 parts also compatible with the RM 250 of the same era?

Many of them are. Suzuki shared a number of components across the RM 125 and RM 250 within the same generation; the main difference is the engine parts, as the 125 and 250 generally have completely different engines. We list both bikes in the fitment for the relevant parts. One thing to note: sometimes Suzuki developed or changed something on one bike before the other, so while the same part could fit both models, the years they fit may differ. Always check the individual product page before purchasing.

What can I do if I can't find the Suzuki RM 125 part I'm looking for?

Our product range is constantly changing and evolving, and both our suppliers and ourselves are always developing and adding new products to the range. We work closely with riders, teams and customers to refine and improve our product offering on a daily basis, so if there is something you're looking for that you can't find on our website, feel free to contact us to discuss further.