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sometimes, when you think of that piston moving around in the cylinder, you wonder how it isnt creating a sonic boom cause its moving so fast.

take the stroke and max RPM of the 09 450R

62mm
11270 RPM

62mm x 2 = 124mm of travel per revolution.

.124 x 11270 = 1379.48 meters of travel per minute.

1379.48 x 60 = 83848 meters traveled per hour.
divide that by 1000 to get 83.84 kilometers per hour.
converted to MPH, you get 52 miles per hour.

yep, your piston is only moving around 52 miles per hour at max RPM on a new breed 4 stroke.

yeah, its fast, but when you consider a high power rifle bullet moves in excess of 1000 meters per second, which equals out to be 2200 or so MPH, the speed of that piston seems kind of paltry doesnt it?

A bullet doesnt accelerate then stop dead then accelerate 22,000 times a min, to me thats the amazing part.

F1 at 24,000 rpm are the motors to look at if you wanna talk about serious piston accel/decel.

Forgive me if I am wrong, but you have woked out the average speed of the piston.

If I am correct the instaneous speed of the piston is much greater, it has to stop and start twice for each revolution.

I did know the formula for working out the instaneous velocity of a piston, but that along with a lot of other knowlege has been losted.

britincali wrote:A bullet doesnt accelerate then stop dead then accelerate 22,000 times a min, to me thats the amazing part.

F1 at 24,000 rpm are the motors to look at if you wanna talk about serious piston accel/decel.

Yes they are pulling 24,000 rpm but they have a really short stroke, so the speed they attain may not be as fast as you think.

Try a big block Chev pulling 9,000 rpm that would be some serious piston speed / instaneous velocity.

oh, i am well aware of the rapid acceleration/deceleration a piston undergoes, and it boggles my mind for sure. I wonder how much the piston"weighs" as its changing direction and throwing probably hundreds of G's onto the rod. i just never imagined that it was only moving at 50 some miles per hour.

Yes you right it is amazing what is happening inside an engine, unless you work it out you won't know how fast or slow it is actually moving.

To be honest I have never sat down to work out how fast a motorcycle engine would be going, thanks for the thoughts though.

CR500R7 wrote:Forgive me if I am wrong, but you have woked out the average speed of the piston.

If I am correct the instaneous speed of the piston is much greater, it has to stop and start twice for each revolution.
?

Velocity and speed are 2 different things entirely. the max speed of the piston is 52MPH, regardless of how many times it starts or stops. because every time it stops, it decelerates from 52-0MPH, and every time it accelerates it goes from 0-52MPH.

i know exactly what you are getting at, but you are definitely thinking of the velocity, not the speed. and since i suck ass at physics, i cant calculate velocity, and even if i could, since we dont apply velocity to everything we do, the large value for the piston's velocity would be meaningless as we would have nothing to compare it to in our daily lives.

knowing what that 4 oz. piston (or whatever weight that piston is) exerts when it is changing direction would be an interesting figure to know though.

I wasn't trying to give you a hard time, I was good at physics but I can't remember all the shit I need to work this crap out at the moment.

Obviously you understand what I am getting at, but I may of got it a bit mixed up.

If I could remember this shit it would make a lot more sense.

Sorry I wasn't trying p!$$ you off.

I seen some info like this on a top fueler one time ...it was increadable.

racein01 wrote: ...it was increadable.

If you havent yet you should see them in real life, it was a life changing day for me the first time, kinda like an 8th wonder of the world

CR500R7 wrote:I wasn't trying to give you a hard time, I was good at physics but I can't remember all the shit I need to work this crap out at the moment.

Obviously you understand what I am getting at, but I may of got it a bit mixed up.

If I could remember this shit it would make a lot more sense.

Sorry I wasn't trying p!$$ you off.

oh, you didnt irritate me in the slightest man, it actually made me think about what you were saying. and yes, you are right, the velocity of those and the G-forces exerted are nothing short of a wonder.

I hate the internet, cause tones can get mis-interpreted, sorry if the last post came off as being irritated

Speed is change in distance over time, Velocity is the same with the added component of direction. So in this context speed is interesting, but velocity is very interesting. It is the G-force around the change in direction at TDC and BDC that is the big engineering challenge in high-revving engines.

redrocket190 wrote: It is the G-force around the change in direction at TDC and BDC that is the big engineering challenge in high-revving engines.

Valvetrain harmonics are a bigger issue....

Well it's a good thing that CR500's don't have a valve train, less shit to break.

CR500R7 wrote:Well it's a good thing that CR500's don't have a valve train, less shit to break.

Too bad Danny's bike cant say the same

So true.

CR500R7 wrote:Forgive me if I am wrong, but you have woked out the average speed of the piston.

If I am correct the instaneous speed of the piston is much greater, it has to stop and start twice for each revolution.

I did know the formula for working out the instaneous velocity of a piston, but that along with a lot of other knowlege has been losted.

Brit forgot to tell you,...... you forgot to add this into the equation of lost knowledge.

That's probably why brit forgot to tell me, to much of a good thing.

NightBiker07 wrote:

CR500R7 wrote:Well it's a good thing that CR500's don't have a valve train, less shit to break.

Too bad Danny's bike cant say the same

but it starts so easily, runs so smooth, is so fuel efficient, hasn't boiled over once, etc. etc. now to take care of that damn chain slider issue!!! burned through the acerbis in one day out at dumont. My new TM designs full kit is at MFDBs waiting for me to pick it up. Aparently the problem is that they lifted the swingarm pivot 10mm, which apparently helps the bike hook up much better than the '08, but puts a lot of chain pressure on the slider If the TM starts to wear quickly, I will just run a 14t front.

the real wonder about engines at high rpms are the connecting rods, those damn things go through hell! if you've ever seen a motor turning , but open so you can see it, it just looks like there are so many forces trying to destroy those rods.

at MFDBs

I heard his wife is HOT!!!

Gomez wrote:

at MFDBs

I heard his wife is HOT!!!

Santa's little helper....

dannygraves wrote: but puts a lot of chain pressure on the slider If the TM starts to wear quickly, I will just run a 14t front.

there ya go. then drop about 3 teeth in the rear to keep the same ratio, and kaboom, problem solved.