Motorcycle.com

captainwhoopass · 05-21-2003, 03:06 PM

Ugghhh. If you want to believe that the satellite teams' bikes are just as good as the factory Honda efforts, go right ahead, but I don't.

SeanAlexander · 05-21-2003, 03:45 PM

KPaul, I suspect that you are deliberately being obtuse. WHY has been answered time and again.... It is simply because we can't make anything strong enough to withstand the punishment required for more than xxxxxrpm with x stroke and x reciprocating weight. I NEVER NEVER said that it was theoreticly impossible with "ideal" materials. Why the hell are you using true unobtanium in infinity to discuss real world engines?

Duken4evr · 05-21-2003, 03:58 PM

Being faster in a street racing situation involves skill for sure, but mostly it involves who is willing to place the biggest bet going around a blind corner.

I recently did a track day. I was faster than some, some were faster than me. There was no bull*****. It was a completely honest experience that I highly recommend!

SeanAlexander · 05-21-2003, 04:11 PM

LOL, you're truly lost here. We are dealing with REALITY not with THEORY. The only thing in this discussion that has to do with physics is the equation used to determine the peak forces acting on reciprocating parts.

Is this a correct statement: "Stresses will increase at a given rpm, if you increase stroke" ?

Is this a correct statement: "Stresses will increase at a given stroke, if you increase rpm" ?

Are you honestly claiming that in the REAL WORLD, we could take a REAL piston + con-rod + misc bearings & pins and reciprocate them through an XXmm stroke at any rpm we please?

Are you honestly claiming that in the REAL WORLD, a heavier assembly won't reach it's structural limits at a lower rpm than a lighter assembly made of the same materials, at the same stroke length?

Are you honestly claiming that in the REAL WORLD, the reciprocating parts of an engine aren't limited by their ability to withstand the forces generated by reciprocation?

KP, I'm NOT arguing theoretical stuff here, I'm honestly asking you if you think that today's superbike engines aren't limited to a certain rpm, by the ability of their reciprocating parts to withstand the accelleration generated by their stroke?

SeanAlexander · 05-21-2003, 04:16 PM

After re-reading this thread I think I've figured it out.

You have been arguing apples to our oranges. We are not talking about what is possible in a textbook, or what is possible with perfect materials, perfect desigh and a perfect environment. We are talking about what is currently REALLY limiting rpm in the longer stroke motors (or in motors with heavier reciprocating parts)

YOU are arguing about what "Should" be. Unfortunately, that has little bearing on this discussion or on current motorcycle race engine building.

seruzawa · 05-21-2003, 04:29 PM

No, I was thinking of the Big Red CB1000.

At least neither are 600s. Couldn't take the razzing KPaul would give me.

seruzawa · 05-21-2003, 04:32 PM

You can improve your 600's torque by getting what is called a "torque wrench". Weld it onto the end of your crankshaft and give it a kick every time you need that extra special boost.

Trust me.

Mashuri · 05-21-2003, 09:04 PM

KPaul, Sean has a point here. What he's basically saying is that the real limiting factor is piston speed. It's that speed and the requirement to stop and reverse it every half RPM that eventually ends up with a rod thrown through the engine block. As stroke increases so does piston speed, further limiting maximum RPM. Now a smaller bore piston is a little lighter but not enough to offset the increased speed of the longer stroke. As always, too much of a good thing is detrimental. The more oversquare you go, the less volumetric efficiency you have, the more piston weight you have and the wider an overall engine you have.

KPaulCook · 05-22-2003, 07:04 AM

Sorry Sean, I really lost my temper back there sorry. No disrespect but I should of learned long ago not to argue science with the untrained novices you and the guy who start ed this thread. After talking to my mechanical engineering buds across the hall they noted that there are large engine 4000cc fours (each cylinder is 1000ccc) capable of sustained 20,000 rpm. They agreed with me that stroke doesn't limit rpm it just a dimenson (measurement). You seem to preoccupied with reciprocating bodies like they are some how different then the rest of physics. To the untrained eye I guess it is but to the trained engineer it isn't. Keep in mind acceleration can be caused by any change in velocity (which has two components speed and direction) UCLA has a good physics department go see them

Mashuri · 05-22-2003, 08:12 AM

Funny, my uncle is a mechanical engineer and he told me (talked to him yesterday) that increasing stroke will lower redline IF the weakest link happens to be the connecting rod/piston assembly. For the longest time valve gear was what determined an engines redline but lately, in most modern engines, it's the connecting rods that fail first. Now F1 and maybe MotoGP have hit their ceilings because of valve gear again so con rods aren't as much of a worry yet. But I believe superbikes and most definitley streetbikes aren't getting valve float/vibration issues. The weakest link is the connecting rod so increasing stroke will put more stress on it, therefore lowering the engine's redline.

05-21-2003, 03:06 PM	#111
captainwhoopass Founding Member Join Date: Nov 2001 Posts: 1,671	Re: '03 Best of the Best Feedback Ugghhh. If you want to believe that the satellite teams' bikes are just as good as the factory Honda efforts, go right ahead, but I don't. __________________ <blockquote> \"I knew it. I\'m surrounded by a$$holes.\" [b][i]Lord Helmet, Spaceballs

05-21-2003, 03:45 PM	#112
SeanAlexander Founding Member Join Date: Nov 2001 Location: Newport Coast, CA Posts: 1,538	Re: Go back to school Sean. Intuition can only be used by sucessfully by women KPaul, I suspect that you are deliberately being obtuse. WHY has been answered time and again.... It is simply because we can't make anything strong enough to withstand the punishment required for more than xxxxxrpm with x stroke and x reciprocating weight. I NEVER NEVER said that it was theoreticly impossible with "ideal" materials. Why the hell are you using true unobtanium in infinity to discuss real world engines? __________________ I thought I'd found true happiness in my personal bath body bar.... Then I tried DOVE! with 1/4 moisturizing cream!!!

05-21-2003, 03:58 PM	#113
Duken4evr Founding Member Join Date: Nov 2001 Location: Parker, CO Posts: 706	Re: '03 Best of the Best Feedback Being faster in a street racing situation involves skill for sure, but mostly it involves who is willing to place the biggest bet going around a blind corner. I recently did a track day. I was faster than some, some were faster than me. There was no bull*****. It was a completely honest experience that I highly recommend!

05-21-2003, 04:11 PM	#114
SeanAlexander Founding Member Join Date: Nov 2001 Location: Newport Coast, CA Posts: 1,538	Re: Sean's big theory of cylinders i.e. big s go slow LOL, you're truly lost here. We are dealing with REALITY not with THEORY. The only thing in this discussion that has to do with physics is the equation used to determine the peak forces acting on reciprocating parts. Is this a correct statement: "Stresses will increase at a given rpm, if you increase stroke" ? Is this a correct statement: "Stresses will increase at a given stroke, if you increase rpm" ? Are you honestly claiming that in the REAL WORLD, we could take a REAL piston + con-rod + misc bearings & pins and reciprocate them through an XXmm stroke at any rpm we please? Are you honestly claiming that in the REAL WORLD, a heavier assembly won't reach it's structural limits at a lower rpm than a lighter assembly made of the same materials, at the same stroke length? Are you honestly claiming that in the REAL WORLD, the reciprocating parts of an engine aren't limited by their ability to withstand the forces generated by reciprocation? KP, I'm NOT arguing theoretical stuff here, I'm honestly asking you if you think that today's superbike engines aren't limited to a certain rpm, by the ability of their reciprocating parts to withstand the accelleration generated by their stroke? __________________ I thought I'd found true happiness in my personal bath body bar.... Then I tried DOVE! with 1/4 moisturizing cream!!!

05-21-2003, 04:16 PM	#115
SeanAlexander Founding Member Join Date: Nov 2001 Location: Newport Coast, CA Posts: 1,538	Re: Sean's big theory of cylinders i.e. big s go slow After re-reading this thread I think I've figured it out. You have been arguing apples to our oranges. We are not talking about what is possible in a textbook, or what is possible with perfect materials, perfect desigh and a perfect environment. We are talking about what is currently REALLY limiting rpm in the longer stroke motors (or in motors with heavier reciprocating parts) YOU are arguing about what "Should" be. Unfortunately, that has little bearing on this discussion or on current motorcycle race engine building. __________________ I thought I'd found true happiness in my personal bath body bar.... Then I tried DOVE! with 1/4 moisturizing cream!!!

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05-21-2003, 04:29 PM	#116
seruzawa The Toad Join Date: Nov 2001 Location: 8501 ft. Posts: 17,400	Re: I'm pretty sure that's funny! No, I was thinking of the Big Red CB1000. At least neither are 600s. Couldn't take the razzing KPaul would give me. __________________ http://www.badmovies.org/movies/deadalive/ I kick @ss for the Lord!

05-21-2003, 04:32 PM	#117
seruzawa The Toad Join Date: Nov 2001 Location: 8501 ft. Posts: 17,400	Re: Hard times for KPaul You can improve your 600's torque by getting what is called a "torque wrench". Weld it onto the end of your crankshaft and give it a kick every time you need that extra special boost. Trust me. __________________ http://www.badmovies.org/movies/deadalive/ I kick @ss for the Lord!

05-21-2003, 09:04 PM	#118
Mashuri Founding Member Join Date: Jun 2007 Posts: 57	Re: Go back to school Sean. Intuition can only be used by sucessfully by women KPaul, Sean has a point here. What he's basically saying is that the real limiting factor is piston speed. It's that speed and the requirement to stop and reverse it every half RPM that eventually ends up with a rod thrown through the engine block. As stroke increases so does piston speed, further limiting maximum RPM. Now a smaller bore piston is a little lighter but not enough to offset the increased speed of the longer stroke. As always, too much of a good thing is detrimental. The more oversquare you go, the less volumetric efficiency you have, the more piston weight you have and the wider an overall engine you have.

05-22-2003, 07:04 AM	#119
KPaulCook Banned Join Date: Nov 2001 Posts: 2,756	Go see a Dr. (Phd) Sorry Sean, I really lost my temper back there sorry. No disrespect but I should of learned long ago not to argue science with the untrained novices you and the guy who start ed this thread. After talking to my mechanical engineering buds across the hall they noted that there are large engine 4000cc fours (each cylinder is 1000ccc) capable of sustained 20,000 rpm. They agreed with me that stroke doesn't limit rpm it just a dimenson (measurement). You seem to preoccupied with reciprocating bodies like they are some how different then the rest of physics. To the untrained eye I guess it is but to the trained engineer it isn't. Keep in mind acceleration can be caused by any change in velocity (which has two components speed and direction) UCLA has a good physics department go see them

05-22-2003, 08:12 AM	#120
Mashuri Founding Member Join Date: Jun 2007 Posts: 57	Re: Go see a Dr. (Phd) Funny, my uncle is a mechanical engineer and he told me (talked to him yesterday) that increasing stroke will lower redline IF the weakest link happens to be the connecting rod/piston assembly. For the longest time valve gear was what determined an engines redline but lately, in most modern engines, it's the connecting rods that fail first. Now F1 and maybe MotoGP have hit their ceilings because of valve gear again so con rods aren't as much of a worry yet. But I believe superbikes and most definitley streetbikes aren't getting valve float/vibration issues. The weakest link is the connecting rod so increasing stroke will put more stress on it, therefore lowering the engine's redline.