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With the classic bikes it matters not to me whether they are of the two stroke or four stroke variety. Both have their advantages and drawbacks and frankly, when a classic shows up, i'm all over it. Motocross was ruled by four strokes, big heavy Triumph's, BSA'S, FN'S, ect. Then Derek and Don Rickman designed a lightweight, strong, and well built bike for motocross, which you could fit your choice of engine. In the early days, most of the Rickman bikes sported a triumph, or BSA engine. The below pic is the "king of cool", Steve McQueen riding his 650cc Triumph powered desert racing bike circa 1966.
 As the mid 1960's approached, the four stroke began to loose its monopoly on the sport to the two stroke bikes such as Husqvarna, Maico, CZ, Bultaco, and Montesa. These were the first wave of purpose built machines for the sport of motocross. All had their strengths and weaknesses, but they were a lot lighter, faster, and pretty much did everything better than a four stroke. By 1970, the four stroke was dead, and the two stroke was king.
 As time went on the Japanese factories got heavily involved in the sport. Technological innovation took over and by the mid 1970's, there were several different lines of two stroke powered bikes available to the consumer. As an example, it's 1977, you are 16 years old and are at your local Yamaha dealer. Cigarette smoke fills the air and over the radio, AC/DC are playing Let There Be Rock. You have a couple grand burning a hole in your pocket and you are looking for a 250cc dirt bike.....what model do you choose?? YZ-250 motocross, DT-250 dual purpose, IT-250 cross country, or the TY-250 trials??
 Then as the early 1980 began , the two stroke met a lot of howling, and whining from those supposedly "in the know" . Apparently the two stroke engine polutes much more than the four stroke does...not only emmissions, but also noise pollution, and apparently, that noise pollution may disturb a chipmunk, or a bird, and make it angry..and you know, rodents and birds have rights too. So the tree huggers whined, raised funding, lobbied the politicians, and got their way. Dual purpose bikes, such as the DT-175 were banished from North America at the end of 1981. Motorcycles built for off road only, or closed course competition, survived into the 2000's. With all the talk of global warming, supposed carbon taxes, Al Gore, ect, which in my opinion is bullshit, the remaining two strokes were phased out by a new breed of competiton four stroke.
One manufacturer in particular pushed this idea as they really never wanted to produce two strokes anyways, but were forced into it when the other three began doing it. The new generation of four strokes do make impressive power, but at a very high cost to the end user. To enable a four stroke to make huge ammounts of power, everything inside the engine is lightened up. The piston's in the new bike's are just big enough to support the rings and wrist pin...that's it, no skirts, nada..they don't even make a decent ash tray! Crank shafts have a life span of 80 to 100 hours..that's it. When these engines blow up the owner is looking at $2500.00 and up to have it rebuilt...so that in 80 hours of future use, they can spend another couple of grand all over again!! Really..well i have a 44 year old bike in my collection ,which is a two stroke twin that still runs on it's original crank and pistons...and with 43000 miles on the clock!! Seems to me that the manufacturers would rather sell millions in replacement parts, than to build a quality, reliable motorcycle, like they use to. So in the end the treehuggers got their way, the government made it law, the manufacturers make more money on parts, and everyone is happy except the end user, who pays too much for the bike in the first place, and gets the shaft when it blows up...but, all may not be bad news....
With modern advancements in two cycle lubricants, and some state of the art, computer designed, prototype two strokes being tested, I'm predicting their return sometime in the future. Both Bombardier, and Ossa are working with new designs that produce the power surge we all know and love, but with emmissions that leave the snivelers nothing to complain about...well, maybe the odd chipmunk or bird!! And with that, all i have to say is ," TWO STROKE POWER!!!"
The following picture is the new Ossa 280i engine, currently used in their trials bike. The cylinder is slanted backwards, is fuel injected piston port, located where the exhaust would traditionally be, and viceversa for the exhaust. It's reputed to be a superb engine, and may be the future......
 .......Well, the future is here, and it's a two stroke Ossa enduro 250. At this point, the bike is a prototype....a very cutting edge prototype, but my feeling is that it if performs as well as it looks, others will have no choice but to develope new two stroke models, or step aside. This is just what two stroke lovers have been waiting for and none too soon!!!
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