Two Stroke Four Stroke History Review
by Matt Vaines
(Barnsley South Yorkshire England)
I am 35 and have been riding dirt bikes on and off for 25 years. In that time bikes in general have become a lot lighter (in weight). Back in the 80's / 90's 4 strokes in particular were big heavy things. The most interesting developments appear to be in the power of the modern 4 stroke as they are not the bikes they once were. In weight or power.
A good race tuned 4 stroke is now crossing the finish line in a time close to that of a good race tuned 2 stroke. The race scenario is a drag style out and out power race. That been said although 2's and 4's appear (power wise) to be more evenly matched than they once were, the story still remains the same. Power delivery.
On paper they may well have similar stats but in the saddle they are still very different bikes. 4's being smooth and user friendly, yes faster and much improved but still smooth and constant. Manageable. And the 2 stroke is and always has been (in my 25 years) an all or nothing aggressive brute that needs a steady and respectful hand.
On the race track (motocross) back in the 80's / 90's the difference in power delivery became evident in the mud. Because 4's had a constant even power delivery they tended to do much better when things got slippery, sometimes even won a few races. I am referring to the days when 2 strokes were clearly faster and won virtually every race, every time.
This power delivery linked with the modern day power increase and slim fast weight loss has made the 4's a formidable motocross bike. I never thought I would hear myself say it, but even with no rain, on some tracks the 4 is the better bike. I would even go so far as to say that under most circumstances
the 4's are better.
However the 2 stroke is built for one thing, to rev out high and hard and it does exactly that. I am from an era where the kx and cr500s were the big track daddy. (If you check the forums these engines are still competitively used in dune and hill climb races.)
My friend also recently returning to motocross, (now not track racing) riding had a friendlyish local field and jump race and came in 2 bike lengths in front. My mate on his old cr500 v a new Crf450. Given the Crf is a modern bike better breaks suspension handling and lighter. I was impressed my pal beat him, JUST. After the crf guy left the verdict was if the track had more turns and the like my mate as bone headed as he is admitted he might have been the one sulking. On realizing this he has ordered a cr500af which for all intents and purposes is a modern crf 450 with a cr500 engine as the cr500r is no longer in production. Can a new light bike with the 500 2 stroke engine be beaten on a big track, probably not.
My take on this is: a moderate rider racing for cash should be on a four stroke and a very good rider on a track that allows the brave to get the power down should be on a two stroke if he or she can deal with the power curve. It will always depend on how much power you can put down. I don't just mean on the back lanes plowing the field I mean power that's driving you forward i.e. power and traction. - Thanks for giving us your spin on things Matt. I would love to get my hands on one of those Af500's! And you're right, the modern four strokes are bloody nice bikes and ride well.