Breaking The Rules In Racing

Great cheats in motocross racing

This article was originally published in the November 2017 issue of Dirt Rider.

We don’t condone cheating. We also don’t condone crime, yet we realize shows like World’s Dumbest Criminals can be fun to watch. In that spirit of “enjoy but don’t emulate,” we convinced some industry insiders to share some of the more ingenious rule-breaking tales they’ve heard of, witnessed, or in some cases were involved with.

This story focuses on technical cheats with motocross and supercross bikes. We skipped the standard methods of cheating, like big-bore motors, in order to bring you the more clever ways around the rules.

Dirt Rider
One racer from the 1980s had a reputation for getting good starts, and the story goes that his mechanic would install a sponge soaked with nitro fuel in the carburetor just before the race.Rich Lee

Nitro-Soaked Sponge in Carburetor

Source: Non-participant
Plausibility: Plausible
Era: 1980s
Success: Never caught

We came across two versions of this cheat.

One racer of the ’80s had a reputation for getting good starts, and the story goes that his mechanic would install a sponge soaked with nitro fuel in the carburetor just before the race. The rider could blip the throttle on the line to warm up his bike but would avoid any big throttle openings. Once the gate dropped he’d twist the throttle wide open, which would of course lift the slide in his carburetor—where above it sat the nitro-fuel-soaked sponge that would then get squeezed to dump its oxygenated fuel into the intake. This high-horse­power surge would last just long enough to get the bike ahead of all others off the line.

The version out of Europe tells of another team using this method at the 125 GPs, and since the team didn’t want to use up the all of the nitro fuel before the start, they would push their bike to the starting line to save the nitro blast for the gate drop. The rest of the teams got suspicious at one particular event, which had a steep hill going from the pits to the start, when the team in question pushed their bikes up the steep hill to the start while everyone else rode their bikes up the hill.

Dirt Rider
It’s rumored that one team would dip their aluminum frames in acid, which would eat away a small layer of the frame, making it lighter and more compliant.Rich Lee

Fuel-Cheat Variation

Source: Non-participant
Plausibility: Rumor
Era: Early 2000s
Success: Never caught

A variation of the “fuel cheat” happened during the period when the AMA outlawed unleaded fuel.

The AMA would spot-check teams by taking small samples out of the fuel tank of a bike after a race. So to get around it, this team would put small amounts of the “illegal fuel of their choice” in the float bowl of the carburetor just before the start so it was available when the rider was ready to rip off a holeshot!

By putting the illegal fuel directly into the float bowl, it was never detectable in the fuel tank.

"Legal" Illegal Fuel

Source: Participant
Plausibility: It happened
Era: Mid-2000s
Success: Caught

In one unfortunate twist of fate, a factory team was penalized for an infraction it was not guilty of.

In the mid-2000s, during the legendary “illegal fuel” fiasco, this team was penalized for running leaded fuel, though the mechanic we spoke to swears his team was running legal fuel at the time, and that lead residue in the tank from the off-season had tainted the AMA’s testing.

During the 2006 Supercross season, three top riders were penalized on three successive weekends for running illegal fuel, though many think the tests were picking up lead residues from other sources.

The Frame Dip

Source: Rumor
Plausibility: More legend than reality
Era: Turn of the millennium
Success: Never caught

When aluminum frames hit the market, a lot of the teams struggled to get them to handle the way they wanted them to. At the start of each season, each manufacturer is required to submit a frame for homologation, and at different times during the year the AMA would check team bikes to make sure the frames they were racing had the same dimensions as the frames submitted at the start of the season, so teams were not able to make changes to the geometry of the frames without getting caught.

It’s rumored that one team would dip the aluminum frames in acid, which would eat away a small layer of the frame, making it lighter and more compliant. The big knock on aluminum frames was that they were too rigid, so the old “acid dip” method accomplished two goals.

Dirt Rider
While the mechanic washed the bike, he would stick the power washer nozzle into the end of the silencer and fill it and the exhaust pipe with water to make the bike heavier so it would get the machine over the weight limit requirement.Rich Lee

That's A Wrap

Source: Participant
Plausibility: It happened
Era: Mid-1990s
Success: Not caught

Some “cheats” fall into a gray area. According to the rule book, it’s illegal to add ballast to a bike, but when one team discovered their bike was underweight and didn’t want to add back weight they had metic­ulously removed from critical parts, they added some weight in an area that would be more beneficial: down low. The bike had a carbon-fiber skid plate, so the team built a steel skid plate and wrapped it in carbon fiber so it appeared as though it was solid carbon fiber.

The part itself was not illegal, but adding ballast to a bike to get an advantage is.

Stretchy Tanks

Source: Witness
Plausibility: Plausible
Era: Late 1990s
Success: Never caught

There was one year that a certain team was having problems running out of fuel at the outdoor rounds, and at that time there was a production tank rule in effect. Since teams were required to run stock fuel tanks or plastic replicas of the same volume, the team couldn’t run a larger tank.

So the solution was for the team to make a plastic fuel tank that was so thin that when it was heated up and fuel was forced into it, the stock-looking tank would stretch enough to hold an extra quart. The tanks still appeared stock, so the AMA was none the wiser.

Fill 'Er Up

Source: Witness
Plausibility: It happened
Era: Mid-1970s and 1980s
Success: Caught

Saving weight is always a big issue with factory teams, and when you’re running a bike that’s lighter than the rules allow, covering up the fact becomes a big concern. Here is one team’s answer to concealing the actual weight of their bike.

After each race, the top three bikes are impounded (sometimes bikes were chosen at random). The mechanics were required to wash the bikes before impound to get an accu­rate weight since, of course, mud on the fenders and skid plate and frame will make the bike weigh more. So while washing his bike in the 1980s, one sneaky mechanic would stick the power washer nozzle into the end of the silencer and fill it and the exhaust pipe with water to make the bike heavier so it would get that machine over the weight limit requirement.

Before that, in the ’70s, the AMA weighed the bikes by putting a strap around the handlebar and one around the subframe and then suspending the bike off the ground from a large scale. In our witness’ account, when the AMA lifted this mechanic’s bike it raised the front end first and when it did, water ran out of the back of the silencer and the mechanic was busted!

The Plastic Transmission

Source: Participant
Plausibility: It happened
Era: Late 1990s
Success: Caught but not penalized

In the late ’90s, a lot of money was being thrown around in a “win at all costs” mentality that a lot of the teams had bought into. In addition to spending top dollar on the best riders, factory teams were spending late hours in their workshops looking for ways to get a competitive edge on their rivals.

One weight-saving trick the team in question resorted to was to replace fourth and fifth gears in their transmission with either plastic gears or gears that were shaved wafer thin—then a stop was used to prevent the bike from reaching these gears. After all, in supercross, first through third is all anyone really needs, right?

Tampering with the transmission is against the rules, and the AMA impounds the top three bikes after each race to check for these very infractions. According to our source, the AMA rule book stated the transmission must have the same number of gears as the homologated version of the bike…but didn’t state those gears need to be functional.

Dirt Rider
The mechanic grabbed the closest item he could find and threw it into the airbox to add weight. Imagine the AMA’s surprise when it looked in the airbox and found a chain inside.Rich Lee

Chain Reaction

Source: Participant
Plausibility: It happened
Era: Mid-2000s
Success: Never caught

One mechanic told us a story about seeing the AMA catch another mechanic trying to add weight to his “slightly under­weight” bike. Apparently, the mechanic was surprised when the AMA alerted him that his bike was going to be “spot” weighed, and in a panic, he grabbed the closest item he could find and threw it into the airbox to add weight. Imagine the AMA’s surprise when it looked in the airbox and found a chain inside. We also heard other reports of mechanics dropping wrenches and sockets into the airbox to add weight.

Sound Test Cheats

Source: Participant
Plausibility: It happened
Era: Mid-2000s
Success: Never caught

When the AMA tightened up its sound regulations in the mid-2000s, teams scrambled to find ways to either conform to the rules or find ways around them. Mechanics were doing all kinds of crazy things to lessen the noise from their bikes. One mechanic told us he discovered that holding the clutch in helped reduce noise from the engine, while gripping the bike with his knees deadened the noise coming from the frame. This all added up to less overall noise.

One of the most ingenious ways to get around the sound test was to alter the ignition mapping so that the bike produced less noise at the rpm the AMA tested the bikes at. Of course, the ignition would be switched back to the proper map for the race. This, again, could fall into a gray area, since teams routinely change mapping on the bikes throughout the day, especially after practice, if the rider desires a different setup.

Carbon-Fiber Hubs

Source: Participant
Plausibility: It happened
Era: Mid-2000s
Success: Never caught

At one point, the AMA rule book stated that hubs made exclusively of carbon fiber were illegal. As one mechanic told us, if you read that literally, then you could use a carbon-fiber hub as long as part of it was made of some metal. So the team made carbon-fiber hubs with very thin aluminum sleeves, which rendered the hubs technically “legal.”