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2-strokes more power/cc than 4-strokes?

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I'm starting to get the drift that a 2 stroke has more power than a 4 stroke of the same size. Is that right?

Thanks.

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You're gonna get all kinds of good technical detail from others, but as a rough estimate you can almost double the cc's going from 2stroke to 4stroke - almost

For example a 250cc 2stroke will be about equal to a 450cc 4stroke in the 'feeling' of power. But then you have to figure in the added weight of the 4 stroke and also account for the torque of the stroke which is where the power is delivered i.e low in the RPM vs the HP of the 2stroke which is where its power is delivered i.e high in the RPM. Totally different to ride.

Gotta have one of each!

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a 2-stroke can make more power than a 4-stroke of the same size. It will also weigh less. However a 4-stroke can rev a lot higher. In the past a 2-stroke made double the power of a 4-stroke with half the weight. However 4-stroke technology has come very far and 2-stroke technology has not changed in the 90s. So now a 2-stroke will make something like 30-50% more power and still weigh about 30-50% less.

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A 2 stroke makes not quite double the HP per cc that a 4 stroke does, but the the 4 stroke makes its power over a wider rpm range vs. the 2 stroke which is why some prefer it

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a 2-stroke can make more power than a 4-stroke of the same size. It will also weigh less. However a 4-stroke can rev a lot higher. In the past a 2-stroke made double the power of a 4-stroke with half the weight. However 4-stroke technology has come very far and 2-stroke technology has not changed in the 90s. So now a 2-stroke will make something like 30-50% more power and still weigh about 30-50% less.

I thought a 2t revs higher than a 4t

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when they say a 2stroke makes more horse power it is more peak horse power.

and the difference is not 30-50%

a 144 ktm 2stroke, has 1 extra hp at peak over the 250f, (both new 2008 standard bikes on dyno, one right after the other)

but then the 250f will have so much more down low. that is the real difference

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I see noone has explained why yet. If you think of how a 2-stroke cycle works, there is combustion on every revolution of the crank. A 4-stroke combusts on every other revolution. This explains why equal displacement engines will have vastly different power outputs.

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:moon:

I see noone has explained why yet. If you think of how a 2-stroke cycle works, there is combustion on every revolution of the crank. A 4-stroke combusts on every other revolution. This explains why equal displacement engines will have vastly different power outputs.

:cheers: Exactly

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I see noone has explained why yet. If you think of how a 2-stroke cycle works, there is combustion on every revolution of the crank. A 4-stroke combusts on every other revolution. This explains why equal displacement engines will have vastly different power outputs.

he din't ask why, but rather asked that if a 2stroke and 4stroke are of equal displacement, would the 2stroke would be more powerful

and the simple answer is yes

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yes the two stroke makes more power per cc than the fourstroke but the way the power is delivered to the ground is vastly different. i have both a 250 2T and a 450 4T and love them both for different applications

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I thought a 2t revs higher than a 4t

a 2 stroke redline is around 9k rpm's and most 4 strokes are around 14k rpm's. These aren't exact numbers but a ballpark figure.

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a 2 stroke redline is around 9k rpm's and most 4 strokes are around 14k rpm's. These aren't exact numbers but a ballpark figure.

Obviously you've never messed with Kart engines. A Yamaha 100 cc 2-stroke kart engine will easily rev to 14,000 rpm.

I'd bet most 125 bike engines are easily over 10,000 rpm. Maybe a bigger 2-stroke like a KTM 300 might stay below 9,000.

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2 stroke engines make more power per CC. Argue all you want, IF you want, but it's true. Always has been true, always will be true. It's not a matter of "feels like more power", or "rides like more power", it simply DOES make more power.

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The assumption that a 2 stroke inherently has a peakier powerband is also completely incorrect.

Any engine (4 stroke OR 2 stroke) will end up w/ a much more narrow powerband when you attempt to extract maximum hp from it. In a 4 stroke this would require very radical cams, etc... In a 2 stroke this is accompliched by a tuned resonance expansion chamber.

The thing is that if a 2 stroke does not need maximum hp then it can have a wider, broader, torquier, and still greater hp peak than any 4 stroke.

There were many lightly tuned, broad powerbanded, trail bike 2 strokes built in the 1970's that still were far superior to any 4 stroke (in the same state of tune and of the same displacement) in all areas of power delivery.

If for instance a 2 stoke 250 were allowed to compete against 4 stroke 250s and the manufacturers lowered peak hp to near or just slightly greater than modern 250F levels, the 250 2 stroke would have more torque, a wider powerband, etc... than the 4 stroke no doubt about it.

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All I have to say is I feel like I'm cheating when I go against the 250Fs, but rules are rules and I am simply following them lol.

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Obviously you've never messed with Kart engines. A Yamaha 100 cc 2-stroke kart engine will easily rev to 14,000 rpm.

I'd bet most 125 bike engines are easily over 10,000 rpm. Maybe a bigger 2-stroke like a KTM 300 might stay below 9,000.

http://en.wikipedia.org/wiki/Yamaha_YZ250

http://en.wikipedia.org/wiki/Yamaha_YZ125

I stand corrected. My bad. See what you get for just guessing :moon:

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The current crop of MX bikes from the big 4 (+1) rev to 12 to 14k because thay HAD TO make them rev that high to try to equal the power output of a comparable 2 stroke. Thats why they are the wink of an eye from being a bunch of hand grenades. Sure, you can get a comment from an owner saying "I'm going on 3 years now with the same top end." But then many follow with "well, I really take it cool most of the time-never hit the rev limiter." After reading all these comments from owners and reading between the lines a little, I have decided I will NEVER own an "f" bike.

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Obviously you've never messed with Kart engines. A Yamaha 100 cc 2-stroke kart engine will easily rev to 14,000 rpm.

I'd bet most 125 bike engines are easily over 10,000 rpm. Maybe a bigger 2-stroke like a KTM 300 might stay below 9,000.

dirt bike engines arn't kart engines, a 125 will hit maybe 11k, a 250 2t mxer will hit 9k but stops making power at around 8k, where as most 250f's redline at around 13.8k and 450 around 11.5k, a crf150R hits the limiter at almost 15k rpm.

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yes the two stroke makes more power per cc than the fourstroke but the way the power is delivered to the ground is vastly different. i have both a 250 2T and a 450 4T and love them both for different applications

'Zactly :moon: - That is why I have a 200 2stroke and a 426 4stroke in the garage. Think of it as dating a spicy red head and having a bruenette on the side :cheers:

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