2016 YZF450 4-stroke Photo: transworld
2016 YZF450 4-stroke
Photo: transworld

There is no question that things innovate and get better over time, and one that we wanted to point out and talk about it is the modern day four-stroke engine. There was a time when the four-stroke and two-stroke were two totally different types of riding. I was lucky enough to grow up around motor cycles and four-wheelers and the four-stroke at the time was normally used for mountain trail type riding. The bikes weren’t necessarily fast but they seemed to have a lot more torque. They still had a ton of power, but it came on gradually so it was a lot easier to control when on the tight technical trails you find here in the Rocky Mountains. The nice part about the four-stroke is it was easy to learn how to ride it and you quickly became comfortable with the power delivery. Now the other style of course was the two-stroke engine. They were much faster and because of the “power band” the power would come in with the ferocity of a nitrous or turbo boost so it was substantially more difficult to learn how to tame those wicked machines, yet arguably more fun.

1985 Honda XR600 4-stroke Photo: motorcyclespecs
1985 Honda XR600 4-stroke
Photo: motorcyclespecs
1985 CR250R 2-stroke Photo: dirtbikerider
1985 CR250R 2-stroke
Photo: dirtbikerider

The two-stoke dominated the pro motocross and supercross circuits since the 1950’s. When the American Motorcycle Association (AMA) started the official AMA Motocross championship in 1972 and then two years later the AMA Supercross Championship the two-stroke led the way in the 250cc class. In the beginning the even had a 500cc class for all the maniacs out there that thought they could handle the power coming from a 500cc two-stroke. But after just two years you didn’t see any more of the big bikes on the Supercross series because they were such smaller tracks the riders weren’t able to utilize even half of the power and people were getting hurt. Because the Motocross tracks were substantially larger the big 500cc bikes were able to open up a little more and in most cases that wasn’t a good thing. But it definitely made things more entertaining that’s for sure. The 500cc class lasted until 1993 when Mike Larocco won the last Championship riding a Kawasaki KX500, which was the bike that had won four of the last five years with varying riders.

Mike LaRocco on his KX500 in 1993 Photo: dirtbikemagazine
Mike LaRocco on his KX500 in 1993
Photo: dirtbikemagazine

One place where the two-stroke would show its dominance over the four-stroke is the sand dunes. For example, if you tried to ride a ’92 Yamaha Warrior that had a 350cc four stroke engine up Sand Mountain like I did, you’d only make it about half way before it started bogging out and you were forced to turn around. On my way back down the hill there happens to be a stock Yamaha Banshee that came flying past me on his way to the top, while doing a wheelie. How was that possible? The Banshee comes with a 350cc engine so the only difference was it was a two-stroke. Now I will admit, I’m not a mechanic or an engineer. But what I can tell you though is that there was no question that the two-stroke was significantly faster, or at least felt much faster. That Banshee was one of the funnest machines to ride because you had those extra wheels when the power band kicked in so you felt a lot more confident staying in it when the front wheels were picking up off the ground. Don’t get me wrong, the four-stroke was still a blast, it just seemed like you always wanted more power.

1992 Yamaha Warrior Photo: orlandoforums
1992 Yamaha Warrior
Photo: orlandoforums
1992 Yamaha Banshee 2-stroke Photo: ebay
1992 Yamaha Banshee 2-stroke
Photo: ebay

But that all got flipped upside down in the late 1990’s. Due to the environmental impact that two-strokes were making there was constant pressure on the manufacturers to come up with a more efficient and environmentally friendly engines, yet also maintain the power. In 1997 Doug Henry made history when he rode a Yamaha Prototype YZF400 in a AMA Supercross event becoming the first four-stoke to win an event. Henry then came back the following year to take home the 1998 AMA Motocross 250 Champion riding on his YZF400 four-stoke becoming the first AMA Champ using that type of bike. At this point other manufactures jumped on board and before long every company had a four-stoke model. By 2004 every bike on the AMA Motocross track was a four stroke.

 


 

Now as sad as it makes me to say, as I get older I’m not able to ride as much. I never had the opportunity of riding one of these modern four strokes until recently. I jumped on a 2009 YZ450F the other day and the guy that owned it told me “be careful it will pull the front wheel up in every gear”, which I didn’t pay any attention to. I had owned a YZ250 back in the early 2000’s and that thing would absolutely pull the front tire up in every gear once the powerband kicked in and I thought there was no way it would pull harder then that. So I Jumped on this 450 and the first thing that I notice is how much different it was than the four-strokes I learned on. It felt closer to the “dirtbike” feeling you got from the two-stroke bikes. So I take off and in first gear the throttle is so responsive its almost pointless to use, and sure enough with barely a twist of the throttle the front tire comes off the ground. As I switch to second gear I give it a little bit more throttle and before I could even think the front wheel had come up. Third gear, fourth, fifth all the same thing. The power delivery is so smooth but at the same time ferocious. It’s almost as if its the perfect combination of power of the old two-strokes but yet the ride-ability of the four-strokes. No wonder all the top riders in the world have switched over to the 450 class. These things are amazing! I was only able to ride it for a short time but without a doubt I will be riding it again, very soon. However, I may have come to the realization that If I had that much power and only two wheels there would most definitely be some injures. So as say a healthy alternative, I just need to add another couple wheels to the mix and get one of these high performance quads that have taken that brutally powerful 450CC power plant and stuffed into a four wheeler. Sounds like a perfect mix, right?

2016 YZ450F 4-stroke Photo:motorcycle-usa
2016 YZ450F 4-stroke
Photo:motorcycle-usa
2016 YZ250 Photo: performancecycles
2016 YZ250
Photo: performancecycles

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