2004 Suzuki RM125 Rebuild | Resurrecting a Relic

Two-Stroke Blast from the Past

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Photos by Austin Rohr & Casey Davis | @austinrohr397 & @air_d617

I've wanted one of these bikes for as long as I can remember. This generation of Suzuki RM125 was the first full-sized motocross bike I'd ever seen and it was the bike that the riders I idolized growing up were piloting.  Over the years, it was always in the back of my mind that I would pick one up sooner or later if the opportunity presented itself. Throughout my teenage years and into college, though, I never really had the extra money to pull the trigger. During that time, older two-strokes were becoming harder and harder to find, and the bikes that did survive were almost always in miserable shape. Not looking for another project, I continued to search and save with patience, waiting for the right one to pop up.

My opportunity finally came last January when I spotted this 2004 Suzuki RM125 for sale. It was exactly what I was looking for, and even the original plastics were in immaculate condition with the warning labels still stuck on. At $1900, the price was a little steep, but still reasonable. There was no denying that a few repairs needed to be made, but everything seemed to be in working order and it was the best I'd seen in all of my time searching. In fact, this model, in particular, holds the 2004 TransWorld Motocross 125 shootout crown. I jumped on the ad the same day it was posted and set off early the next morning for a three-hour drive through a snowstorm to take a look at it. Upon arriving and looking the little 125 over, I decided that buying the bike was a no-brainer and before I knew it, I was headed home with a grin from ear to ear and a new machine in my truck.

Rebuild

No matter how hard you examine a used motorcycle, it's always best to expect the worst. In the case of this particular bike, its outward appearance and condition seemed excellent for its age. The chain and sprocket, tires, brake pedal, and the clutch lever would definitely need some love, but that's to be expected after 13 years. After some freshening up and maintenance, it was time for its inaugural first ride. Sadly, this revealed some new, very great concerns that I had not anticipated or caught when I inspected the bike prior to buying it. Particularly, a crack in the center case at the drain plug was a major issue. Although patched with JB weld by a previous owner, that temporary solution had failed and oil was now making a mass exodus from the center case of the motor. This meant the motor would need to be removed and torn down, and the case would either need to be repaired or replaced.

From that point forward, it became clear that the last 13 years had taken their toll. Even though the machine was lightly used for its age, it suffered from a lack of proper maintenance and some MacGyver-inspired handiwork. One perfect example was the airbox, which had cracked at some point. Rather than address the issue properly, someone had applied Liquid Nails to patch it up. While this did fill the crack, the airbox was still falling apart and the construction adhesive had dried and began flaking off. Aside from the DIY repairs, there were also troubling discoveries, including a hole in the swingarm that likely came from one of the sprocket bolts backing out. By this point, it came as no surprise that nearly every bearing and seal had gone bad as well.

Luckily, all hope was not lost. After some digging around on eBay, a center case was ordered up and on its way. The motor was then handed over to Jay Clark, who has done the work on countless project bikes. Not only did he assemble the motor with the new case, he was also able to identify some issues unique to the RM that almost certainly would have gone unnoticed otherwise. Using one of Wrench Rabbit's complete kits, which includes parts from Vertex and Hot Rods, the motor was freshened up while it was already torn down. This was topped off by Millennium Tech who stripped down, repaired, and re-plated the cylinder to get it back to OEM spec. A Hinson clutch basket was also installed to improve the worn feeling of the clutch. Next, a pair of Boyesen covers wrapped the motor up and gave it a new factory look. Helping the new motor to breath, a Twin Air filter was installed, and fresh air is now delivered through a Moto Tassinari V-Force reed cage. On the other end, an FMF Factory Fatty pipe and Power Core II Shorty silencer handle the two-stroke’s fumes.

While the powerplant of the RM was being attended to, the forks and shock were sent off to enzo racing to get dialed in. Even if the fork seals hadn't been leaking, getting the suspension tuned on any new bike is a must. When this bike came out in 2004, it's Showa spring components weren't revolutionary, but they were praised for comfort and good handling. Fast forward 13 years later, and they still hold their own. With fresh internals and love from enzo, the suspension on the little 125 was ready to go again. Meanwhile, the steel frame was in need of some attention. A short trip down to Chris Johnson at San Diego Power Coating got the ball rolling and soon we found a unique metallic bronze color.

Slowly but surely, the bike began coming together. Most of the main components were now handled and what was left were the small odds and ends that are easy to forget about. Unfortunately, parts for these older RMs are becoming increasingly hard to find. Several purchases from eBay were necessary to replace many parts on the bike. The ugly truth of the matter is that as the years go on, it becomes harder and harder to find parts - used, new, or aftermarket - for some of these bikes. It is by no means impossible to restore them, but there are additional challenges involved in finishing a project like this.

There are still some companies out there who supply parts for the final generation of the RM125 though, and this made all of the difference in getting the bike back together. The rusty stock pegs were swapped with a set from IMS, and foot controls were ordered up from a European company, AS3 Performance, who were the only ones still making aftermarket brake pedals and shift levers for the 125. At the rear of the bike, a TM Designworks chain guide and chain rollers were installed to provide protection. Perhaps most importantly and often neglected, Pivot Works bearing kits were used to replace nearly every bearing on this bike, from the steering stem to the linkage.

After months of pressing bearings and scouring the internet for hard to find bits and pieces, the bike was nearly complete. A second trip was taken to Jay's, where a new set of Dunlop MX3S tires were mounted up. Also installed were a set of Supersprox sprockets and a Works Connection Elite clutch perch and brake lever. Among the few things that didn't change were the Renthal 971 handlebars that I had bought the bike with. The installation of a new set of Renthal Kevlar half waffle grips put the finishing touches on the controls.

Last, but not least, the bike would need a visual facelift. I couldn't bring myself to cause harm to the original plastics and graphics, so I stored them away safely and picked up new plastics. These were then wrapped in a custom set of blue and yellow graphics from Chaos MX. For both visual appeal and ergonomics, a Seat Concepts ribbed seat cover was installed. With the finishing touches installed, the bike was finally ready to hit the track a year after I had brought it home.

The Verdict

When I originally picked up this RM125, I had hoped it would be a fun, low-cost bike to have in the garage, while simultaneously fulfilling a dream of mine to own one. As you can probably tell by this point, things didn't exactly go according to plan. It took countless hours, bloodied knuckles, and a good chunk of change to make this bike function properly, and that's with a lot of help along the way! I haven't sorted through the receipts and added things up yet, but to purchase and build this bike comes out to about $6000 total. In comparison, a brand new 125 retails for only slightly more these days. From that perspective, it might seem hard to justify buying something older and deal with the inevitable issues and work, and for some people the choice is simple. Despite that, I'd still argue that there's good reason to invest in an older project bike.

A project of this nature may not have been my intention, but there's something to be said for the smile and feeling of satisfaction every time you open the garage door and lay eyes on a bike that you've put so much of yourself into. Every detail is unique to you and you know everything there is to know about the bike. Even more so, it's a pure joy to swing a leg over a machine that reconnects you to the early days of falling head over heels for the sport. In the end, that's worth any amount of time and money, and it is great motivation to get out and spend more time in the saddle. Now all that's left is to deal with is the terrible mess I've made in the garage!

Parts List

Engine
-Wrench Rabit rebuild kit
-Vertex piston
-Hot Rods complete crank
-Pivot Works bearing kit
-Millennium Technologies Cylinder re-plating
-FMF Factory Fatty pipe & Power Core II Shorty silencer
-MotoTassinari V-force 3 reeds
-Twin Air filter

Chassis & Suspension
-San Diego Powder Coating sandblasting, powder coating “Dee Bronze” and superdurable clear, and race prep masking
-enzo racing fork and shock rebuild
-Pivot Works linkage, steering stem, and swingarm kits
-Dunlop MX 3s front and rear tires
-Supersprox sprockets
-T.M. Designworks Powerlip chain roller
-T.M. Designworks Factory Edition 1 chain guide
-Warp 9 Titanium sprocket bolt set
-Works Connection aluminum frame guard (for RM250, only fits right side)

Controls
-Works Connection Elite clutch perch
-Works Connection front brake lever
-IMS Pro-Series foot pegs
-AS3 Performance forged brake and shift lever
-Fasst Company rear brake return spring kit
-Renthal 7/8″ 971 bend handlebar
-Renthal Kevlar grips

Accessories
-Seat Concepts Race 2.0
-Chaos MX Graphics “Trifecta Series”

To learn more about the products used for this build, click the links below...

Wrench Rabbit: www.wrenchrabbit.com

Millenium Technologies: www.mt-llc.com

Hinson Racing: www.hinsonracing.com

FMF Racing: www.fmfracing.com

V-Force: www.mototassinari.com

Sand Diego Powdercoat: www.sandiegopowdercoating.com

enzo racing: www.enzoracing.com

Vertex Pistons: www.vertexpistons.com

Hot Rods: www.hotrodsproducts.com

Pivot Works: www.pivotworks.com

Renthal: www.renthal.com

Dunlop: www.dunlopmotorcycle.com

Boyesen: www.boyesen.com

Works Connection: www.worksconnection.com

Twin Air: www.twinair.com

AS3 Performance: www.as3performance.co.uk

Seat Concepts: seat-concepts.myshopify.com

Supersprox: www.supersproxusa.com

Tacoma Motorsports: www.tacomamotorsports.com

TM Designworks: www.tmdesignworks.com

IMS: www.imsproducts.com

Chaos MX Graphics: www.chaosmxgraphics.com