If there was ever a mis-conception to be perpetrated on the motocross public, it’s the fabrication that the four-stroke is in some way superior to the two-stroke. Now before we dive into what has turned into an endless debate, let’s get everyone on the same page first.

The demise of the two-stroke in motocross is politically motivated, plain and simple. There are reasons for this that we will never be privy to. mostly why this insane change was brought about in the first place.

Many people are convinced that the change was motivated purely by money and power. The blame focus shifts between the AMA/FIM and the major manufacturers. It is probably somewhere between the two. Although it is possible that they did not pre-meditate the murder of the two-stroke. Unfortunately the result was the same.

What exactly happened to start all of this? To answer this question intelligently we need step back and take a look at motocross history.

This photo is believed to be from the very first "motocross" race held in 1924

From all accounts the very first Motocross race (called scrambles) was held in England in 1924. Because there were no bikes purpose built for racing at that time, modified street machines were used. The majority of the machines were equipped with four-stroke engines, although a few machines utilized two-stroke engines.

During this time the four-stroke was king-of-the-hill. Most machines used for racing were 500cc in displacement. Although a lightweight class was added not long after that consisted of machines of 250cc. Throughout this period most of the bikes were four-strokes.

In 1947 the first International Team Motocross race was held in the Netherlands. This race turned into the Motocross des Nations in 1949 by the FIM.

During the early years of motocross the mighty 500cc motocross machines ruled the sport.

Just a few short years later in 1952 the FIM inaugurated an individual European Championship for 500cc displacement machines. This became the World Championships in 1957. Then in 1962 the 250cc class was added.

During the entire motocross history, displacement was the measurement for classifying motocross bikes and races. To restate that fact in another way, from 1924 until 1997 motocross classes were determined by displacement.

For those keeping track, for a total of 73 years, displacement was the rule.

During this period of time, development of the two-stroke advanced to the point where they dominated the world of motocross. The two-stroke first vaulted into the forefront in the 250cc class beginning in the late 1950?s and early 1960?s. The big bore bikes needed a few more years to gain an advantage over the four-stroke.

Then in 1996 everything changed. A rogue engineer at Yamaha used some of their Formula 1 technology and applied it to a single cylinder motocross bike. The result was the prototype Yamaha YZF400.

Yamaha lobbied the AMA (some say begged) to allow then to race the YZF400 four-stroke against the 250cc two-strokes. The result? In 1998 Doug Henry won the 250cc National Championship against a field of 250cc two-strokes. Was it because of a lack of competition? No Doug beat a contingent of racers consisting of Jeff Emig, Jeremy McGrath, Ezra Lusk, Kevin Windham, Mickael Pichon and Greg Albertyn.

The 1998 Yamaha YZ400F production bike.

Doug earned five overall wins during one of the most competitive race seasons, to take the championship.

The question becomes, why was no one protesting this? Nothing against Doug or Yamaha, but racing a four-stroke bike that was 150cc ‘s larger than the competitions 250cc two-strokes is cheating.

Remember during this time if a racer was caught cheating by using a big bore (anything over 251cc’s) machine they would be disqualified and lambasted by the media. After all cheating is cheating.

Marketing and the motocross media perpetuated the lie that the four-stroke was more technologically advanced than the two-stroke.

But there was more lurking under cover. Somehow one of the major reasons perpetuated for the switch was due to upcoming EPA regulations, that were too difficult for the manufacturers to meet. The word of a two-stroke ban was bandied about and still to this day people believe this is the reason.

To aid the four-stroke in it’s race to dominance, the AMA banned leaded fuel. Which lead (no pun intended) to a major farce of penalties for minuscule amounts of lead being found in some competitors fuel.

This rule was finally overturned when Ricky Carmichael threatened to drop out of the Supercross series after small traces of lead were found in his race fuel. Which in hindsight, the minute amounts of lead found in any  fuel during the two year “fuel debacle” should not have met with penalties and fines.

Sorry about the segue into fuel,  back to our regularly scheduled program.

While there are many reasons that the four-strokes appear to be superior to their two-stroke competition, truly there is the granddaddy of all reasons. DISPLACEMENT.

Displacement  Disparity
In car racing circles the catch phrase is “There’s no replacement for displacement” , and for good reason. The bigger the engine the faster the machine will be (at least up to a certain point)

According to AMA Pro rules this is equal displacement. 450F piston on the left and Honda CR250 two-stroke on the right.

Only in motocross racing (okay maybe in road racing as well) are the rules lopsided and allow an almost double displacement advantage for a four-stroke.

Because of marketing hype and “experts” talking about the different power characteristics between the two technologies, most folks believe that the four-stroke must be twice the size to compete and that is fair. Some are so convinced of this that they balk at the idea of straight up competition.

The question is, “what are they afraid of?”

Well first they might know something that we don’t, that the two-stroke will be better at equal displacement. The truth is that on some tracks under certain conditions the four-stroke will be superior.

“But the fact remains that even with virtually all R&D money being funneled to four-strokes, they have yet to show a practical advantage unless they have an edge in displacement.” MXA’s 250?s Unlimited

The rule must change to equalize motocross and make it fair.

EPA Regulations

E-TEC direct fuel injection technology allowed Evinrude to win a Clean Air Excellence Award from the EPA.

There are no emission regulations for closed-course racing.  Plain and simple the EPA has not banned two-strokes.

The issue rears it’s head when you take into consideration that motocross bikes are not only purchased for closed course racing. The manufacturers make a great deal of money selling large numbers of motocross bikes that will never see a race course. So compromises become the order of the day.

To reach the levels of emissions that were required for the first level of regulations, the easiest way was to switch to four-strokes. But the technology exists to allow two-strokes to exceed many future regulations.

To read more about the EPA regulations click here
EPA vs Motocross

To read more about the two-stroke technology click here
Two Strokes strike back

Four-Stroke Revolution?
What benefits have the four-strokes brought to the sport of motocross? The biggest advantage of a four-stroke is that it’s easier to ride at speed than a two-stroke. It requires less skill to attempt dangerous obstacles and jumps.

What are some of the negatives? The NOISE is the biggest problem to ever be hoisted on motocross. This one aspect alone is responsible for large numbers of riding areas and tracks being shut down than any other factor.

For less than a few hundred dollars most racers can rebuild their own two-stroke machines.

Cost. For the time being let’s leave out the cost of rebuilds and maintenance. In order to be competitive in the A class or at the National level, you’re required to spend, spend, spend. It costs enormous amounts of money to race a 250F machine competitively.

At the National level the 250F class is ruled by money. If you have enough you can be competitive, if not you will be left behind. This is the reason that so many privateers chose to race the 450 class, less money is required to improve the engine.

Recently MXA magazine featured a KX450F set up for the Glen Helen National. The cost of the upgrades? $12,500! The problem is this does NOT include the cost of the machine itself.

The newest four-stroke machines are technologically advanced. They are fantastic machines and fun to ride/race.

But in no way are they “better” or more “technologically advanced” than a two-stroke. They are just bigger.

The only way to see which one is truly better in professional racing, is to allow pro motocross racers to compete on same displacement bikes regardless of stroke.

Enough of the marketing hype… let’s see straight up displacement competition!