2 stroke - 4 stroke

[Lorna]

Dear Technical Forum,

Can someone, in lamen's terms, please explain the difference between 2 stroke and 4 stroke in biking terms please?

[ma]

In the simplest terms, a 2 stroke fires every time the piston is at the top of the stroke ( once every revolution), and a 4 stroke fires every other time ( every other revolution).

[woodyracing]

i have a couple of nice links to explain 2-stroke and 4-stoke..

4 stroke engine :
http://www.howstuffworks.com/engine.htm

2 stroke engine :
http://www.howstuffworks.com/two-stroke.htm


WoodyRacing

[joseff]

The most common benefit of a 2-stroke engine would be the extra power, since the engine fires twice as often as its equivalent 4-stroke counterpart.

In biking terms, where engines have to be small, it's easier to obtain more power from a 2-stroke than a similar size 4-stroke.

[Airhead]

Hi Lorna,

The magic words "in biking terms" are the key I think.

As 'joseff' has said the small 500cc two stroke GP four cylinder engine is able to produce as much power as a 1000cc four stoke twin cylinder engine. They would both be 'expert only machines' in that all the power is produced at the high end of the rev range.

That's why those guys are paid soooooo much

The weight is lower on the two stroke, and the performance that much better. In very rough terms this is the difference between GP bikes and Superbikes.

[Lorna]

Oh! I see! Thanks very much for all of your explanations. I don't know much about bikes and my friend's husband was going on about them. I couldn't get a word in edgeways to ask what he was going on about!

Thanks!

[rubinhothebest]

Hi, forumers.
I was wondering reading this topic, what were actually the differences between 2 and 4 stroke engines in in the aspect of performance. Because, if 2 stroke are more powerful than 4, why don't F1 teams use it?
Why is everyone at Moto GP wishing to change to 4? I don't understand.

[Alan]

Two strokes are generally very thirsty - four strokes are more efficient and environmentally friendly. Four stroke racers are likely to have more similarities to road bikes and thus there should be more interest in the series as with Superbikes. Also developments from the racing program are more likely to filter down to road bikes.

[pkparker]

2 strokes are banned in formula one regulations

[RWC]

Just a small but interesting point.If 2 strokes were allowed in F1 there would be enormous probs packaging th exausts.2 strokes HAVE to have fat expansion chamber exausts to get the high gas flow though them that gives them their high power.