[alex92]

Another stupid question here.. When a car/bike says revs.. I'm guessing that's revolutions? But revolutions of what? A revolution is usually a 360 degree turn..

I'm guessing 1 rev = piston going up and down once? If so, is it the same on a 2 stroke?

Cheers

 

[Aduro]

One complete revolution of the crankshaft i think? also one complete firing cycle? (4 cylinders on the Cibbie)

I'm basing this on assumption by the way.

EDIT: actually doubt its a full firing cycle now ive thought about it.

 

[Stavros]

I'm guessing 1 rev = piston going up and down once? If so, is it the same on a 2 stroke?

Correct. One rev means one complete revolution of the crankshaft, which corresponds to the piston moving up the bore and then back down again (or vice versa if you start from TDC - that's Top Dead Centre, or the piston right at the top of it's stroke, as high as it can get).

One revolution is equal to two strokes. The piston going down from TDC to BDC (Bottom Dead Centre, or as low as it can get in the bore) is one stroke, likewise the piston going up from BDC to TDC is one stroke.

Two strokes are called that because each cylinder fires once every two strokes, that is, once every revolution.

Four strokes fire each cylinder once every four strokes, which equates to two revolutions. So each cylinder in a CBR is firing every two revs, which means two cylinders are firing per rev.

 

[dayeve]

I started to type an answer and then deleted it because i felti wasnt doing it justice.

This does.
http://en.wikipedia.org/wiki/Revolutions_per_minute

follow links.

 

[Humbug]

how is this possible?

 

[smiley_666]

it is one complete revolution of the crankshaft. usually measured by the number of sparks per an amount of time. i.e. 10 revolutions/ second, 10 sparks per second (on wasted spark ing system, 5 for a conventional ign system) = 6000 RPM.

 

[Sneddy]

how is this possible?

How is what possible?

 

[Drew]

it is one complete revolution of the crankshaft. usually measured by the number of sparks per an amount of time. i.e. 10 revolutions/ second, 10 sparks per second (on wasted spark ing system, 5 for a conventional ign system) = 6000 RPM.

600 you mean yeah?


In a CBR250 at 18000RPM each piston is going up and down 300 times a second

 

[smiley_666]

yes, yes i do.
:blush:

 

[muzza]

it is one complete revolution of the crankshaft. usually measured by the number of sparks per an amount of time. i.e. 10 revolutions/ second, 10 sparks per second (on wasted spark ing system, 5 for a conventional ign system) = 6000 RPM.

600 you mean yeah?


In a CBR250 at 18000RPM each piston is going up and down 300 times a second

That's crazy!