Topic: Split - What is wrong with the stock Honda induction system?

[kghost]

Without doing any calculations on jet size, fluid viscosity, or engine fuel requirements at WOT, you're saying that at WOT, the main jet has reached its maximum flowrate.

It has reached the max flow rate for this instance only because no more pressure differential can be achieved in this situation.

Perhaps if you did your OWN research or educating you wouldn't require folks on the internet.

Some folks here know what is happening reference the main jet.

Theres a whole sub discipline of physics called Fluid Mechanics.

They even discuss your nickname.

Have a brief read:http://en.wikipedia.org/wiki/Fluid_dynamics

Most of the Formula you require to arrive at the scientific certainty you seek is covered by Bernoulli's Equation.

An explaination of the formula is here:
http://en.wikipedia.org/wiki/Bernoulli%27s_principle#Incompressible_flow_equation

You claim to be well versed in all things scientific so you shouldn't have any problems with Bernoulli.

[Laminar]

Without doing any calculations on jet size, fluid viscosity, or engine fuel requirements at WOT, you're saying that at WOT, the main jet has reached its maximum flowrate.

It has reached the max flow rate for this instance only because no more pressure differential can be achieved in this situation.

Perhaps if you did your OWN research or educating you wouldn't require folks on the internet.

Some folks here know what is happening reference the main jet.

Theres a whole sub discipline of physics called Fluid Mechanics.

They even discuss your nickname.

Have a brief read:http://en.wikipedia.org/wiki/Fluid_dynamics

Most of the Formula you require to arrive at the scientific certainty you seek is covered by Bernoulli's Equation.

An explaination of the formula is here:
http://en.wikipedia.org/wiki/Bernoulli%27s_principle#Incompressible_flow_equation

You claim to be well versed in all things scientific so you shouldn't have any problems with Bernoulli.

The problem is that your statement doesn't fit with any of the principles or research I've done.

What I'm asking, for the umpteenth time, is how you KNOW that the main jet has reached its maximum flowrate at WOT.

[kghost]

Very well sir.....

Please feel free to post your principles.

You didn't take the time to read Bernoulli so please post the research you have done.

For the record....I said Restricts.

Given the head pressure in the bowl, the size of the jet, and the pressure in the venturi......What do you think Restricts flow?

Bowl pressure should be atmospheric or there abouts.

Venturi pressure will be dependant on RPM but at  WOT the venturi shape and size is fixed.

Now....put a bigger orifice in the mix......and what have you got?

Enrichment.

You didn't change the venturi size or the atmosperic pressure acting on the fuel in the bowl......

Wheres the restriction?

[sangyo soichiro]

You claim to be well versed in all things scientific so you shouldn't have any problems with Bernoulli.

Bernoulli had a problem with Bernoulli.  Didn't he commit suicide?

(Or at least one of the Bernoulli's did - there were several of them and I can't remember exactly which one offed himself.)


Or maybe I'm confusing them with Boltzmann...

Yup, it was Boltzmann.  Nevermind. 

 

[Markcb750]

You claim to be well versed in all things scientific so you shouldn't have any problems with Bernoulli.

Bernoulli had a problem with Bernoulli.  Didn't he commit suicide?

(Or at least one of the Bernoulli's did - there were several of them and I can't remember exactly which one offed himself.)


Or maybe I'm confusing them with Boltzmann...

Yup, it was Boltzmann.  Nevermind. 

 

Well take heart Soichiro, if Brian Green is right some where there is a universe where Bernoulli did off himself, and where pods are instant power creation devices.   

[754]

Here is a quote from TT from post # 62;
 "Why would you need to change jetting in the carbs if the induction is stock"... that was addressing a question or rather point I had brought up.

 To address that, some of us race our bikes .. ride them to the track and away from the track daily..  There we may uncork the exhaust, bolt on a number plate, maybe add struts, or slicks, or other things, then ride the streetbike on the track.. Track could be 3000 ft or more difference in elevation from home... That is a good reason you may want to change jets..

 Also as a motor runs in and mileage racks up on it, we have noticed the jetting requirements, may change slightly..

  TT mentioned something about a comment I made about OEM usage of pods.. Every XR 750 comes with them as far as I know.. Screaming Eagle Carb kits (sold by The Motor Company) use K&N fliters. Victory, I am not sure, but they may use them. So yes, OEM manufacturers do use them..

 In post # 85 Chickenman addresses me asking TT about what changes he made to his induction motor, exhaust.. which TTchooses not to answer. So from what I have noticed, it seems he is riding a stock exhaust, stock engine, stock induction (perhaps foam filter).The bike though is equipped with a fairing or windscreen. So I will attempt to explain why I asked... Whether it gets taken as an attack, ill intent,  I can not control that, but I assure that is not what I am trying to do..

 What I am simply trying to point out is that the needs of a stock bike are different than that of  some  of the forum users. They have made extensive changes to their bikes.. things like frames, tanks, fairings, monoshocks, 50% bigger engines, extensive porting, different valve and guide sizes, different carbs, a plethora of different exhausts, seating positions, footpeg positions..all variables that in some cases prohibit the use of stock induction, or requiring mods to the stock parts..

 That is what I was truing to point out..

[mlinder]

pods.. Every XR 750 comes with them as far as I know..

What?

Screaming Eagle Carb kits (sold by The Motor Company) use K&N fliters. Victory, I am not sure, but they may use them. So yes, OEM manufacturers do use them..

A list of companies that put form before function... not a real positive endorsement.

[sangyo soichiro]

I remember when I was a little kid on the playground.  All the athletic kids, at one time or another, would seem to end up in a fistfight to see who was the toughest.  All us nerdy smart kids kind of felt left out.  Thank God for the internet....




 

[MickeyX]

Hitler.










 

[MickeyX]

Harley.






 

[scottly]

pods.. Every XR 750 comes with them as far as I know..

What?

Screaming Eagle Carb kits (sold by The Motor Company) use K&N fliters. Victory, I am not sure, but they may use them. So yes, OEM manufacturers do use them..

A list of companies that put form before function... not a real positive endorsement.
[/quote

Excuse me, but the HD XR750 was Not an example of "form before function"!!!!

[MRieck]

This thread is disintegrating.
 Turbulence....once that engine is revving to 6,000 or 7,000 or  9,000RPM charge is going in both directions.....I've posted that before.  There is no such thing as "still air" in the airbox. There is all sorts of turbulence in there as the raw fuel in the box proves. It's like a hurricane. Airbox cutaway drawings with arrows really aren't accurate. It's like saying...it kinda works this way (which it does I guess). Engines are dynamic...when you try to pin static properties, or slow,constant physical properties to them things go wrong. I say this more based on porting, People actually think you can "bend" air like plastic to get it to do what you want. Sorry...air moving at almost supersonic speeds goes straight and that's all it wants to do.
 Did I miss the part about big reversion into a small airbox? Please repost it if I did and I apologize. Thanks guys.
  

[754]

Form over function... kinda sounds like the Fury...

[HondaMan]

Turbulence....once that engine is revving to 6,000 or 7,000 or  9,000RPM charge is going in both directions.....I've posted that before.  There is no such thing as "still air" in the airbox. There is all sorts of turbulence in there as the raw fuel in the box proves. It's like a hurricane. Airbox cutaway drawings with arrows really aren't accurate. It's like saying...it kinda works this way (which it does I guess). Engines are dynamic...when you try to pin static properties, or slow,constant physical properties to them things go wrong. I say this more based on porting, People actually think you can "bend" air like plastic to get it to do what you want. Sorry...air moving at almost supersonic speeds goes straight and that's all it wants to do.
 

Good point.
When we built the roadrace engines that ran at (then) stratospheric speeds like 14k-16k RPM, the ones that ran the best had both open velocity stacks and longer stacks. (This was a problem for the 750 because the frame gets in the way...)
Even so, the engines that ran above 14000 RPM were prone to fire at the velocity stacks because of the turbulence you're talking about, "M". The spitback at speed would wet the area immediately around the open stacks with fuel. This is why fires on racebikes used to be such a common thing in those days. Fuel injection has reduced this a lot.

[TwoTired]

This thread is disintegrating.
 Turbulence....once that engine is revving to 6,000 or 7,000 or  9,000RPM charge is going in both directions.....I've posted that before.  

Doesn't that depend on valve timing, or the camshaft used?

Sorry...air moving at almost supersonic speeds goes straight and that's all it wants to do.

Do you have any number relating RPM to air speeds, with a given cam grind?  Were they based on calculations or some measurement data?

[manjisann]

When we built the roadrace engines that ran at (then) stratospheric speeds like 14k-16k RPM, the ones that ran the best had both open velocity stacks and longer stacks. (This was a problem for the 750 because the frame gets in the way...)
Even so, the engines that ran above 14000 RPM were prone to fire at the velocity stacks because of the turbulence you're talking about, "M". The spitback at speed would wet the area immediately around the open stacks with fuel. This is why fires on racebikes used to be such a common thing in those days. Fuel injection has reduced this a lot.

They make a cream for that burning sensation 

Brandon

[MRieck]

This thread is disintegrating.
 Turbulence....once that engine is revving to 6,000 or 7,000 or  9,000RPM charge is going in both directions.....I've posted that before.  

Doesn't that depend on valve timing, or the camshaft used?

Sorry...air moving at almost supersonic speeds goes straight and that's all it wants to do.

Do you have any number relating RPM to air speeds, with a given cam grind?  Were they based on calculations or some measurement data?

Yes to that question. Every cam has an overlap period which provides the opportunity for charge to move in both directions. Less overlap will reduce reversion, more overlap will increase it. More lift and duration will increase overlap but get more charge in the cylinder. You could have a cam with .200 lift and 200 degrees of duration and have very little reversion but performance would be very poor at anything over idle.
 I don't have a specific cam grind vs air speed chart. I'm sure there are some available from people who develop and manufacture cams.

[MRieck]

Turbulence....once that engine is revving to 6,000 or 7,000 or  9,000RPM charge is going in both directions.....I've posted that before.  There is no such thing as "still air" in the airbox. There is all sorts of turbulence in there as the raw fuel in the box proves. It's like a hurricane. Airbox cutaway drawings with arrows really aren't accurate. It's like saying...it kinda works this way (which it does I guess). Engines are dynamic...when you try to pin static properties, or slow,constant physical properties to them things go wrong. I say this more based on porting, People actually think you can "bend" air like plastic to get it to do what you want. Sorry...air moving at almost supersonic speeds goes straight and that's all it wants to do.
 

Good point.
When we built the roadrace engines that ran at (then) stratospheric speeds like 14k-16k RPM, the ones that ran the best had both open velocity stacks and longer stacks. (This was a problem for the 750 because the frame gets in the way...)
Even so, the engines that ran above 14000 RPM were prone to fire at the velocity stacks because of the turbulence you're talking about, "M". The spitback at speed would wet the area immediately around the open stacks with fuel. This is why fires on racebikes used to be such a common thing in those days. Fuel injection has reduced this a lot.

You bet. For reasons TT mentioned earlier (regarding length).

[mlinder]

pods.. Every XR 750 comes with them as far as I know..

What?

Screaming Eagle Carb kits (sold by The Motor Company) use K&N fliters. Victory, I am not sure, but they may use them. So yes, OEM manufacturers do use them..

A list of companies that put form before function... not a real positive endorsement.

Excuse me, but the HD XR750 was Not an example of "form before function"!!!!

DIdn't say the xr750 was form over function, but typically, HD and Victory are.

Form over function... kinda sounds like the Fury...

I don't know anything about "The Fury".

Also, is this not a 'stock' XR750? I thought it was, but could be wrong.

[eurban]

Found this while cruising Ebay.  Set of milled delrin velocity stacks combined with a pair of dual port KN oval filters.  Distance from the filter to the carb is improved over standard pod setup and if the velocity stack setup is milled properly, it should avoid turbulence from poorly engineered "steps" in the typical pod.
http://cgi.ebay.com/ebaymotors/Custom-Velocity-Stacks-for-CB750-KZ650-K-N-filters_W0QQitemZ220565865661QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item335ac004bd

[mlinder]

Velocipod!

[crazypj]

I'm bored with this engine doesn't NEED laminar airflow, engine couldn't care less (being a chunk of metal).
 Laminar flow may make engine work more efficiently but, it rarely if ever happens at most rpm.
 Intake system has about 14psi PUSHING air into cylinder.
Honda did the best they could with available technology, keeping within various government regulations/restrictions (worldwide, not just USA)
If your operating at top end of RPM range, airbox IS restrictive to a certain degree, bike uses more fuel than necessary in most cases (my CB550 was doing about 26mpg all stock, 591 kit, cam, exhaust, correct jetting, 41mp at higher speed about same rpm's checked over 70,000+ miles)
 In my experience, pods can be made to work  more efficiently than stock airbox but its real difficult with a stock motor. Sidewinds are only an issue when your going slow or stopped.
 A 20mph gust isn't going to have much, if any effect at 70+mph, it may push the entire bike sideways causing you to THINK the engine is cutting out, but, after 70,000+miles on my 550 it's not something I've even noticed or had a problem with.
 Spitting back is more a cam timing issue, too much overlap with narrow lobe centers and lowish rpm, plus, ignition timing set for 14,000 rpm? (38~40 Deg advance? fixed timing, or stock advance mechanism?)
 Nice CG pic, problem is still the same though, frame gets in the way for a 'correct' length induction system

PJ

[754]

mlinder, that is an Ironhead XR, used for I think the first 2 yrs.. probably only made 68 hp. The alloy XR's came out soon after with the twin carbs, they easily made 85+ hp, some over 100...not to shabby for a 750cc..

 Thre Honda Fury, is Honda's full on chopper..

[chickenman_26]

 Thre Honda Fury, is Honda's full on chopper..

1300cc of sanitized, Japanese Fury. When appliances go wild...
 

[camelman]

Mlinder,

I like the velocipod.  It eliminates the pumping work losses that the stock system is plagued with.  TT's comments at the beginning of this saga are very well researched, and show the quality work that went into the stock system, but it remains that the path from intake to engine is very tortuous with the stock design.  Every bend and ridge in the intake creates pumping losses in the intake system that the engine has to provide the power to overcome.  Pumping loss has a real impact on engine power and volummetric efficiency, and that is what pod filters are able to reduce, and what a design like the velocipod is able to reduce.

I like the stock system, but it can definitely be improved upon... easily.

Camelman
Heat Transfer and Fluid Dynamics Engineer (yep, I'm legit)