Photo: Casey Davis

It is perfectly understandable for "Junior" to be dazzled by the latest model bike, but in all actuality the differences between a brand new small wheel motorcycle and one that is a few years past it’s release are miniscule. This is because other than a five cubic centimeter increase in displacement, the mini bike class has seen little in new technology in recent years. One quick scan of a parts catalog reveals the true scope of this, as a part from 2012 can work on a model from the previous century. Though many parents have picked up on the concept of buying a brand new yet dated bike, the initial coin dropped is still quite high. This can quickly deter a family that is looking to start riding or one that is simply taking the next step in size. But that is where the beauty of the classified ad comes in, which is where we found our most recent overhaul.

With a list of graduates that can be seen at any Supercross main event, it is difficult to name a top lever racer who hasn’t competed aboard a KX80 or 85 at some point in their career, thanks in part to the Team Green amateur program. After just a few simple modifications, the stock KX can be turned in to a fire breathing mini fit for adolescent domination. But the bikes that Adam Cianciarulo and the other Team Green prodigies compete aboard are vastly different than our KX. While their bikes are factory fresh from top to bottom and still have sticker residue from the warning labels, our little project has been subject to neglect and abuse.

When we first encountered the mini on Craigslist, it was five years old and in dire need of repair. A scarred cylinder and expired crank were the result of a maintenance schedule that was lackadaisical at best. Tired suspension components, controls, and bearings not only compromised the handling of the bike, but also the safety of the rider. Our final area of concern was in the drive train, as the chain, sprocket, and tires had very little time remaining before they would ultimately fail. After handing over the desired $400, we loaded the bike and headed straight to renowned bike builder Jay Clark, who shared our vision of a budget ripper that would also be the envy of the pits.

Photo: Casey Davis

We will be the first to admit that this is not for the faint of heart, time, or mechanical ability. The bike was in poor condition and a complete disassembly was required to fix the damage. After separating the frame from the engine, Jay sanded and repainted the chassis with aerosol paint from the local hardware store. At this point we inspected the various bearings, repacking those that were deemed useable and discarding the others. Luckily that list was short, as only the wheel bearings and steering stem failed to meet our standards and were replaced by new units from Pivot Works. The addition of the Renthal handlebars and a Works Connection lever allowed us to discard the damaged controls and tailor the bike to the rider even more.

Compared to some of our past projects, the KX received little in terms of new parts in an effort to keep the cost at a minimum. Rather than splurge on a new cylinder, the original was simply striped and re-plated by Millennium Tech of Wisconsin. Once we received our repaired jug, the crew at Parapros Racing began to piece the motor back together using a Hot Rods crank, Vertex piston, and a Cometic gasket kit.With the bike being built with a beginner level rider in mind, the compression and stroke of the motor was not altered for performance. The addition of a Moto Tassinari V Force Reed Valve and FMF exhaust system were not a means to increase output, but rather to spread it more evenly across the power band. A fresh Uni air filter ended the possibility dirt ruining the engine while CV4 hoses replaced the dry and damaged plumbing. As the engine was in the midst of being rebuilt, the suspension was shipped to MB1 for new seals and fluid. The internals on both ends were still in proper working order and weight for our needs and were used again, a decision that brought the overall cost down. As the outsourced essentials began to trickle back, the re-assembly process began. Getting the power of the refreshed engine to the ground then became the focus, as we paired the new Renthal sprockets, brakes, and chain with fresh Dunlop tires.

At this point the bike was back together and mechanically sound, race ready yet rough in appearance. Any additions made now were purely aesthetic and unnecessary, but were still done with overall cost in mind. Custom graphics from DeCal Works were laid over UFO Plastics, giving the bike a truly one off and new look. A color coordinated seat cover by Motoseat replaced the tattered original black material, and with that the bike was truly finished.

Photo: Casey Davis

As we wheeled the rehashed mini to our test rider, Zachary Taylor, he was unaware of the bike's actual age. After numerous laps and minor adjustments in jetting, the younger Taylor felt confident and comfortable aboard the machine that was half his age. His desire to ride confirmed the theory that when done correctly, a used bike can be just as competitive as one fresh from the crate, but at a fraction of the cost.

Parts List

Hot Rods – Crankshaft ($173.96)/Main Bearing and Seals ($44.95)

Vertex – Pro Replica Piston Kit ($86.12)

Cometic Gasket – Top End ($25.55)/Lower End Gasket Kit ($32.99)

Uni Filter – KX 85 Air Filter ($26.95)

FMF – Fatty Exhaust ($229.99)/Shorty Silencer ($119.99)

Moto Tassinari – V-Force V3 Reed Valve ($148.99)

Dunlop – MX 51 Front ($69.99)/Rear Tire ($63.99)

Works Connection – Elite Perch ($149.95)/Front Brake Master Cylinder Cap ($27.50)/Rear Brake Master Cylinder Cap ($24.95)

Renthal – Front Sprocket($19.95)/Rear Sprocket($64.95)/R1 Chain($38.95)/Front Brake Pads($34.95)/Rear Brake Pads($34.95)/ 7/8" Handlebars($74.95)/Dual Compound Grips ($15.95)

Pivot Works – Front Wheel Bearings($19.95)/Rear Wheel Bearings($24.95)/Steering Stem Bearing Kit($49.95)

CV4 – Formed Silicone Coolant Hoses($90.32)

UFO – Complete Plastic Kit($126.99)

DeCal Works – Semi-custom Graphics($199.99)/Pre-printed Backgrounds($69.95)

Motoseat – Custom Cool Seat Cover($39.95)


Millennium Tech – Strip/Repair Cylinder($174.95)

MB1 Suspension – Change Suspension Fluid/Replace Seals ($100.00)

Parapros Racing – Assemble Engine(Contact for pricing)

Jay Clark

Completed Bike Minus Graphics/Seat/Plastic/Aluminum Accessories – $1987.49 (Plus $400.00 for bike)

Completed Bike With All Parts Listed – $2412.37 (Plus $400.00 for bike)