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The Two-Stroke is only dead if you kill it yourself

by JohnNicholas on 12/09/2008

We have met the enemy and he is us.

Imagine that a major manufacturer could build an engine that was eight pounds lighter than the typical powerplant, revved quicker, produced ten more horsepower (per quarter liter), had one-tenth the moving parts, cost less to maintain, and could be rebuilt for a quarter of the price of a modern engine. Wouldn’t that be wonderful? Shouldn’t that designer win the Nobel prize?

Think about the ramifications for a second. A lighter, revvier, more powerful, simpler, cheaper and easier-to-maitain engine. Where do we get in line? Sorry but that engine has already been designed, built, sold and discarded. It is a two-stroke engine.

So why is everyone riding a four-stroke? The most commonly stated reasons are the EPA, factory development and increased power. In fact, none of these reasons hold water. The EPA does not regulate closed-course machines. And, if they did, how is it that Yamaha and KTM have avoided the EPA’s wrath since the original 2006 EPA standards were announced? Although it seems apropos that R&D has pushed the four-stroke engine past the two-stroke, nothing could be further from the truth. The development of the modern four-stroke, which started in ernest back in 1997, hasn’t really advanced much in the past 11 years. It might seem obvious that everyone is riding a four-stroke because they are more powerful. In truth, cubic centimeter for cubic centimeter, they aren’t more powerful. They are actually much slower. But under AMA rules, four-stroke engines are allowed to be as much as 100 percent larger. That displacement advantage brings their horsepower figures up to those of the best two-stroke engines.

So why is everyone on a four-stroke? Because we all jumped on the bandwagon. When the public bought the 1998 Yamaha YZ400 in droves, Yamaha’s sales bonanza encouraged Kawasaki, Honda, Suzuki and KTM to get a piece of the action. As more marques joined the fray, four-strokes become the cause celebre. In turn, two-stroke sales waned… and once they diminished below the breakeven point, Honda, Suzuki and Kawasaki bailed out. Who killed the two-stroke? The American consumer did.

Have you ever heard a local racer say. “I’m not gonna swith. There is no way that I’m dropping my current engine for one of those things.” Sure you have, but there is a twist in this quote. It doesn’t come from a modern racer refusing to switch from his trusty two-stroke to a four-stroke. It is, in fact, the words of a motocross racer in 1965 resisting the change from four-stroke to two-stroke.

Forty years after the wholesale switch from British four-strokes to small bore two-strokes, American motocross racers have again abandoned their old school engine in favor for the next big thing. The change may seem inevitable. But is it for you?

The MXA wrecking crew wants to offer you four good reasons to stick with the two-stroke:

Manufacturing costs.

It costs more to produce a four-stroke engine-a lot more. Back when four-strokes were competing for your dollar against two-strokes, there was a price parity between the two. Now that the lower cost two-strokes are gone, the price of the four-strokes will rise.


All bikes use the same running gear (chain. wheel, tires, rims, hubs and suspension), so the only place to save weight is in the engine. That doesn’t mean that it isn’t possible to build a 216-pound 450cc four-stroke, just that the same effort would result in a 208-pound two-stroke.


Maybe it is just the MXA wrecking crew, but two-strokes are more fun to ride. The power snaps on, the front end lifts, and the bike squirms under acceleration. They are quick, light and agile. The greatest two-stroke riders are free flowing, hard charging, go-get-’em-style riders.


Four-strokes cost more to own. Don’t get us wrong; they are cheaper on a race-per-race basis, because they require very little in the way of maintenance. But they are ticking time bombs. All race engines have a finite life-span. When a two-stroke wears out, you inspect the cylinder, thrw in a new piston and get back into action for less than $300. Not so with a four-stroke. If it blows up at the end of it’s service cycle, which is approximately two years, it will ding your wallet to the tune of $1,000 to $3,000.

The MXA wrecking crew isn’t denigating four-strokes. We race them and test them. We are simply stating a manifesto for two-stroke diehards. If you are a two-stroke loyalist, more power to you. You don’t have to feel like the odd man out. Your two-stroke choice is justified-totally.

The complete article above was re-typed from Motocross action. Please visit and subscribe to MXA.