Two strokes vs four strokes Subscribe

Having recently "downsized" from a 2010 Husaberg 390, the best big bore four stroke to a KTM 150 XC, a small two stroke enduro chipmunk, here are the biggest differences between the two types of bikes.

Many manufacturers like Honda don't even make two strokes anymore - they think the four strokes are the pinnacle of engineering. KTM has a wide range of two stroke machines and many riders are now switching back. Why?

Four strokes are complex feats of mechanical engineering. With valves and cams and actuators, fuel injection, sensors and computers that constantly adapt, they are certainly much less hassle free to ride. The computers adjust for engine condition and weather and you hardly even have to pull the choke when starting them. Winterizing is a joke (i.e. just put the stuff in the gas and leave them). Maintenance intervals and long, but usually somewhat expensive, since it takes a skilled mechanic many hours to take those top-ends apart.

Two strokes are simple, cheap to build and you can change the top end in the garage, "with the help of a blind monkey". Their carburetors require constant adjusting to suit the weather and are very touchy beasts that work well only on the verge of self-destruction. In fact they do self-destruct and you have to change half the engine every 20-60 hours (piston and rings). Oil changes have to be more frequent as well.

So, why are many choosing the two strokes over the four strokes? You go to any enduro event and 90% of the bikes are orange KTMs, many two strokes.

Because, once tuned, a two stroke tends to generally work well. They are much lighter than the four strokes of the same power. The 150 two stroke makes as much power as my 390cc four stroke, believe it or not: 39hp, except it makes it at the 12,000 rpm and has no torque at the bottom.

The two strokes take more technique to ride - you can't quite relax to keep them going at speed and you have to deal with the power band, while four strokes are easy to ride: they hookup .

The two strokes are lighter more nimble, more agile and don't tire the rider as much: they are safer that way.

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By: Razie | 2014-09-13 .. 2014-09-25 | Tags: post , enduro , dirt bike , selection , review


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