The smog police are catching up with motorcycles - until recently, the last redoubt of relatively unregulated internal combustion.

The Environmental Protection Agency has come down hard on bikes during the past couple of years; beginning with the 2006 models, all motorcycle manufacturers had to reduce the evaporative and nitrogen oxide emissions of their machines bikes by 60 percent. That meant the end of carburetors, which were still commonly used on bikes even though all new cars have been fuel-injected since the late '80s. It has also meant the adoption of catalytic converters across the board (believe it or not, most bikes did not have cats as recently as two years ago) as well as the rise of car-like electronic computerized engine management systems.

This equipment has made new bikes more expensive and complex. The average guy can no longer do service work (beyond the most basic stuff, such as changing the oil).

Just like modern cars.

Emissions control equipment has been installed on motorcycles for many years. But the gear involved until quite recently was minimalist and easily defeated for improved performance. For example, it was a simple thing to re-jet the factory carbs, gut the smog hoses and replace the stock exhaust with a more aggressive aftermarket one.

That's all history now.

Other than a few small cc machines (dirt bikes) and oddballs, virtually all 2010 mode bikes are injected.

Of course, computers are necessary to run the EFI; that means lots of sensors, switches and wiring. Time to add such acronyms as MAP and MAF to your vocabulary. Goodbye jets. Hello fuzzy logic and laptops.

Catalytic converters are here, too. These chemical exhaust scrubbers are built into the exhaust system. As with new cars, it is more difficult to modify the stock exhaust system now, as well as expensive. It's also illegal - though bikes don't have to come in for a smog test.

Yet.

But inevitably attention will focus on motorcycles. More people are riding now than ever before, which means bikes are more visible and thus likely to be targeted. "Tampering" - defeating or rendering inoperative any part of the factory-installed emissions system - is about to become harder to get away with.

And forget about asking your dealer to do it for you.

Until recently, most bike shops would - with a wink and a nod - gut whatever smog gear a new bike came with as part of the tuning process and the quest for maximum power. Just as it was with cars back in the good old days of the 1980s - when you could buy things like a catalytic converter "test pipe" - a hollow section of exhaust pipe designed to fit exactly in place of the factory-installed converter.

Try that with a car today.

Very soon, motorcyclists may face the same harsh reality. Not only will it be harder and more expensive to make any changes to our rides, bike shops will want no part of doing anything that might cause the EPA's hellhounds to descend. And we may soon find ourselves waiting in line to get "smog checked" alongside the cagers.

The irony of it all is that bikes represent a tiny fraction of the daily-driven vehicle fleet - about 2.2 percent of all registered motor vehicles accounting for less than 2 percent of total Vehicle Miles Travelled (VMT) by all registered vehicles in the United States. Sure, that number has increased lately as gas prices have made bikes more appealing - but not by much.

The fact remains that motorcycle emissions are a small percentage of the total, relative to cars and trucks. Focusing all this attention on them is hardly going to affect the air quality equation one way or the other.

All it's going to do is make riding a motorcycle more like driving a car - expensive and filled with hassles.