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oldschoolcarbs
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PostPosted: Wed Dec 04, 2013 8:26 pm Reply with quote Back to top

CV stands for constant velocity. The vacuum operated slide varies the venturi size thus maintaining a constant velocity of airflow.

osc
 
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oldschoolcarbs
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PostPosted: Wed Dec 04, 2013 8:28 pm Reply with quote Back to top

AGDT wrote:
CV stands for (constant velocity). These type carburetors are normally used on motorcycles. A CV carburetor (Constant Velocity) incorporates a vacuum operated slide that varies the venturi size within the carburetor, thus maintaining a constant velocity. The slide also holds a needle that when lifted by the opening slide varies the amount of atomized fuel delivered.


oops ya got there first.

good on ya, mate!
 
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Jebbysan
Red CB1100F
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Joined: Dec 08, 2007
Posts: 7126
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PostPosted: Wed Dec 04, 2013 8:38 pm Reply with quote Back to top

oldschoolcarbs wrote:
Jebbysan wrote:
oldschoolcarbs wrote:
Jebbysan wrote:
The more I think about the airbox....the more I think it was an air resonance plenum.....it could not induce a vacuum as that would be counter intuitive....I feel it had a "ram" effect......
When you remove the box....you have to jet up....as the carbs will lose signal due to not having a "third order resonance" similar to adjusting the length of stacks on a Hilborn injection unit for a V-8....
I also wholeheartedly believe that degreeing the intake cam to open sooner improves carb signal.....

Maybe we can dispell the myth forever.....maybe not......
Just my two cents and please comment on my thinking if you like!

Peace,
Jebby


By all means, educate us further regarding "signal" and how it relates to performance dynamics in situations where various mods are made, beginning from inside the airbox and continuing all the way through to the exhaust tips. A chart would be lovely, or dyno printouts to compare with the ones we made last year.

We've had resounding success jetting for pods, historically speaking (150+ DOHC carb sets with perhaps 5% having pods and/or headers) and because we tend to stay in touch with customers I've accumulated a database of what has worked and what hasn't.

The one thing we're on the lookout for is lean running over time so we advise a few simple tests to ensure that were not slowly burning valves.

Techno-babble is all well and good but well-documented trial and error yields real-life results that are far superior to theory.

We add CBX slide needles to the mix, which in one notable case was the difference between an 1100 not running at all to purring like a tiger.

You can also acquire adjustable needles without the dynojet rapid step-down profile but they're pricey. You just have to know where to look.

As for drilling jets, this is an extremely common track-side procedure, but with one caveat: we don't want to go up more than a size or two because any more than that and we'll change the geometry of the conic cavity on the interior orifice of the jet, which will in turn vastly affect fuel flow.

Interesting to note: While both are indeed metric and thus have the same size orifice, a dynojet #98 main jet delivers more flow than a stock Keihin #98.

OSC



You know what dude? You are just a dick.
WTF do you know about engine dynamics?
You can chart and graph yourself into a corner....but physics do not lie.
My theory has more often than not been correct......
So YOU tell us why you jet up when removing the airbox. Smartguy.

You know what else? Signal is everything....without it...the engine does not run. Vacuum signal is
#1 in the world of carburetors...I figured you would know that.....

Mel...sorry to crap on your thread.

Jebby


Don't get in a twist. I merely asked you to explain the term “signal.” I don't know what for about "third order resonance." A theory that cannot be definitively and repeatably verified is akin to voodoo.

I eschew jargon. Not that esoterica doesn't have its place but I prefer plain English. My customers appreciate it and they're the only ones whose opinions actually matter.

And of course it's all about real-life results so we put a bike on the dyno with EGA sniffer in the exhaust stream and diddle with the carbs to see what's actually going on. Charts indeed!

So anyway,

When the piston goes down it sucks air through the intake valves. Total air volume allowed through is determined by both the degree to which the valves open (lift) and duration of time that they stay open.

Relative “sudden-ness” of valve opening and closing plays a role as well, all of which above factors are determined primarily by the camshaft (and secondarily by valve lash.)

Intake vacuum pulse is mathematically calculable and thus 100% predictable insofar as frequency, amplitude, and duration. The designers used this to balance flow through the entire system, from airbox to exhaust tip. Let's not forget that Honda had the EPA breathing down their necks at every turn and were forced to make changes that didn't necessarily translate to better performance OR fuel economy. (Okay so that's a little understatement. LOL)

Airflow through the venturi is by no means steady like a flowing stream of water, but rather is very jagged.

Air is “stretchable,” which is to say that airbox resistance increases the duration of the vacuum pulse and smooths out the jaggedness.

When we take away airbox resistance, vacuum pulse duration is shortened. The result is that the jets have less time to do their jobs, hence less fuel comes through them.

So we jet up.

As for dynojet, I stay out of that discussion. There are instances where it's a viable solution and others where it makes things worse.

For one thing, if you install a DJ kit when compression isn't perfect you're in for a world of hurt, and you may come away believing that DJ is fundamentally bad science. Nothing could be further from the truth but the predicate conditions must be met before you can have an objective take on it.

The same holds true for any mod to succeed. Compression is king. Let me repeat for those who are hard of hearing: COMPRESSION IS KING.

In the case of pods it's equally vital that the accelerator pump circuit be in perfect working order AND that valve lash is on the money.

OP clearly has this worked out, which is a testimonial to his skills as an engine/carb builder.

Beyond that it can come down to factors as seemingly obscure as fuel quality and elevation above sea level.

With the number of variables in play it can indeed seem like a crap shoot and like I said there are times when mods/DJ are just not going to work.

This is why I ALWAYS advocate for stock setups, while being open to those times where I'm satisfied that everything is in order to safely make the mod.

History bears this out, which is all that matters.

OSC


Signal is a term that is used by EVERY race engine builder in the country......it is the amount of negative pressure required to pull fuel through the jet.....it is a variable that is almost solely quantified by velocity across an orfice.....
The amount of velocity is created by several different variables.....but to simplify....it starts with the piston going down....creating negative
pressure....the speed of the air it is drawing in is determined by the size and shape of the port/spigot/carb throat.....
The idea is to get the air moving as fast as possible.....
Third order resonance is nothing new either....it is also known as "ram tuning" and is used on many new bikes....most specifically the new V-Max variable length stacks or "V-Boost". It is also used in almost every car built today......it is part of the harmonic cycle within a venturi and that is what the airbox does.....it enhances speed through the carb by using the engines natural harmonic cycle...this will "signal" the slide to lift and fuel to be pulled.....

I spent five years of my life understanding this pnenomenom....and once I had it down....I started to use the knowledge to make my engines create more than 100% VE (volumetric efficiency) to inertia supercharge the cylinder.
Back to the word "signal"............more signal=more response
Remove the airbox...lose velocity=jet up so the fuel is easier to pull from the jets. If it tries to pull the slide...it will "signal"

Hope that clears it up for you.

Jebby

_________________
Ass, Grass or Gas....no one rides for free....
1979 CBX
1972 Corvette Stingray Coupe 406/4spd
1982 Z/28
2011 Silverado Crew Cab


"I don't do T and A...because I don't have much of either" Tea Leoni 
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cliffiec
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PostPosted: Wed Dec 04, 2013 8:48 pm Reply with quote Back to top

See, r3, I told you someone would come along to correct me, LOL.

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r3d1100f
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PostPosted: Wed Dec 04, 2013 9:07 pm Reply with quote Back to top

I am honestly blown away by the amount of knowledge the members of this forum have and pass on. I can only hope that one day to have a huge ride where i can meet the people that make this forum badass.

take it easy,
Dave

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Jebbysan
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Joined: Dec 08, 2007
Posts: 7126
Location: New Braunfels,Texas

PostPosted: Wed Dec 04, 2013 9:13 pm Reply with quote Back to top

r3d1100f wrote:
I am honestly blown away by the amount of knowledge the members of this forum have and pass on. I can only hope that one day to have a huge ride where i can meet the people that make this forum badass.

take it easy,
Dave


Soon my friend....soon

Jebby

_________________
Ass, Grass or Gas....no one rides for free....
1979 CBX
1972 Corvette Stingray Coupe 406/4spd
1982 Z/28
2011 Silverado Crew Cab


"I don't do T and A...because I don't have much of either" Tea Leoni 
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oldschoolcarbs
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Joined: Jun 28, 2013
Posts: 311
Location: Santa Clara +CA

PostPosted: Fri Dec 06, 2013 6:10 pm Reply with quote Back to top

Jebbysan wrote:
oldschoolcarbs wrote:
Jebbysan wrote:
oldschoolcarbs wrote:
Jebbysan wrote:
The more I think about the airbox....the more I think it was an air resonance plenum.....it could not induce a vacuum as that would be counter intuitive....I feel it had a "ram" effect......
When you remove the box....you have to jet up....as the carbs will lose signal due to not having a "third order resonance" similar to adjusting the length of stacks on a Hilborn injection unit for a V-8....
I also wholeheartedly believe that degreeing the intake cam to open sooner improves carb signal.....

Maybe we can dispell the myth forever.....maybe not......
Just my two cents and please comment on my thinking if you like!

Peace,
Jebby


By all means, educate us further regarding "signal" and how it relates to performance dynamics in situations where various mods are made, beginning from inside the airbox and continuing all the way through to the exhaust tips. A chart would be lovely, or dyno printouts to compare with the ones we made last year.

We've had resounding success jetting for pods, historically speaking (150+ DOHC carb sets with perhaps 5% having pods and/or headers) and because we tend to stay in touch with customers I've accumulated a database of what has worked and what hasn't.

The one thing we're on the lookout for is lean running over time so we advise a few simple tests to ensure that were not slowly burning valves.

Techno-babble is all well and good but well-documented trial and error yields real-life results that are far superior to theory.

We add CBX slide needles to the mix, which in one notable case was the difference between an 1100 not running at all to purring like a tiger.

You can also acquire adjustable needles without the dynojet rapid step-down profile but they're pricey. You just have to know where to look.

As for drilling jets, this is an extremely common track-side procedure, but with one caveat: we don't want to go up more than a size or two because any more than that and we'll change the geometry of the conic cavity on the interior orifice of the jet, which will in turn vastly affect fuel flow.

Interesting to note: While both are indeed metric and thus have the same size orifice, a dynojet #98 main jet delivers more flow than a stock Keihin #98.

OSC



You know what dude? You are just a dick.
WTF do you know about engine dynamics?
You can chart and graph yourself into a corner....but physics do not lie.
My theory has more often than not been correct......
So YOU tell us why you jet up when removing the airbox. Smartguy.

You know what else? Signal is everything....without it...the engine does not run. Vacuum signal is
#1 in the world of carburetors...I figured you would know that.....

Mel...sorry to crap on your thread.

Jebby


Don't get in a twist. I merely asked you to explain the term “signal.” I don't know what for about "third order resonance." A theory that cannot be definitively and repeatably verified is akin to voodoo.

I eschew jargon. Not that esoterica doesn't have its place but I prefer plain English. My customers appreciate it and they're the only ones whose opinions actually matter.

And of course it's all about real-life results so we put a bike on the dyno with EGA sniffer in the exhaust stream and diddle with the carbs to see what's actually going on. Charts indeed!

So anyway,

When the piston goes down it sucks air through the intake valves. Total air volume allowed through is determined by both the degree to which the valves open (lift) and duration of time that they stay open.

Relative “sudden-ness” of valve opening and closing plays a role as well, all of which above factors are determined primarily by the camshaft (and secondarily by valve lash.)

Intake vacuum pulse is mathematically calculable and thus 100% predictable insofar as frequency, amplitude, and duration. The designers used this to balance flow through the entire system, from airbox to exhaust tip. Let's not forget that Honda had the EPA breathing down their necks at every turn and were forced to make changes that didn't necessarily translate to better performance OR fuel economy. (Okay so that's a little understatement. LOL)

Airflow through the venturi is by no means steady like a flowing stream of water, but rather is very jagged.

Air is “stretchable,” which is to say that airbox resistance increases the duration of the vacuum pulse and smooths out the jaggedness.

When we take away airbox resistance, vacuum pulse duration is shortened. The result is that the jets have less time to do their jobs, hence less fuel comes through them.

So we jet up.

As for dynojet, I stay out of that discussion. There are instances where it's a viable solution and others where it makes things worse.

For one thing, if you install a DJ kit when compression isn't perfect you're in for a world of hurt, and you may come away believing that DJ is fundamentally bad science. Nothing could be further from the truth but the predicate conditions must be met before you can have an objective take on it.

The same holds true for any mod to succeed. Compression is king. Let me repeat for those who are hard of hearing: COMPRESSION IS KING.

In the case of pods it's equally vital that the accelerator pump circuit be in perfect working order AND that valve lash is on the money.

OP clearly has this worked out, which is a testimonial to his skills as an engine/carb builder.

Beyond that it can come down to factors as seemingly obscure as fuel quality and elevation above sea level.

With the number of variables in play it can indeed seem like a crap shoot and like I said there are times when mods/DJ are just not going to work.

This is why I ALWAYS advocate for stock setups, while being open to those times where I'm satisfied that everything is in order to safely make the mod.

History bears this out, which is all that matters.

OSC


Signal is a term that is used by EVERY race engine builder in the country......it is the amount of negative pressure required to pull fuel through the jet.....it is a variable that is almost solely quantified by velocity across an orfice.....
The amount of velocity is created by several different variables.....but to simplify....it starts with the piston going down....creating negative
pressure....the speed of the air it is drawing in is determined by the size and shape of the port/spigot/carb throat.....
The idea is to get the air moving as fast as possible.....
Third order resonance is nothing new either....it is also known as "ram tuning" and is used on many new bikes....most specifically the new V-Max variable length stacks or "V-Boost". It is also used in almost every car built today......it is part of the harmonic cycle within a venturi and that is what the airbox does.....it enhances speed through the carb by using the engines natural harmonic cycle...this will "signal" the slide to lift and fuel to be pulled.....

I spent five years of my life understanding this pnenomenom....and once I had it down....I started to use the knowledge to make my engines create more than 100% VE (volumetric efficiency) to inertia supercharge the cylinder.
Back to the word "signal"............more signal=more response
Remove the airbox...lose velocity=jet up so the fuel is easier to pull from the jets. If it tries to pull the slide...it will "signal"

Hope that clears it up for you.

Jebby


Oh, I know what the terms mean. I worked on carbs for a shop who won the superbike championship two years running. Talk about guys who make practical use of the science and physics of signal.

What I don't understand is how you draw a parallel between injected and naturally aspirated engines' airflow/fuel management.

Since you've opened the subject I'm curious to know how, specifically, did you apply your knowledge of signal and physics to achieve 100%+ VE on your CBX or any other of your machines? This would be an incredibly valuable addition to the knowledge base.

OSC
 
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Jebbysan
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PostPosted: Fri Dec 06, 2013 6:26 pm Reply with quote Back to top

Trial and error.....but I knew which direction to go because of my background.

Apply things that you know make sense...and reward yourself with the results.....

The slides are heavy....and the seal is piss poor.
The velocity is low without airbox.

Jet up....a lot.

Jebby

_________________
Ass, Grass or Gas....no one rides for free....
1979 CBX
1972 Corvette Stingray Coupe 406/4spd
1982 Z/28
2011 Silverado Crew Cab


"I don't do T and A...because I don't have much of either" Tea Leoni 
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magoogle
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PostPosted: Sun Dec 08, 2013 3:34 am Reply with quote Back to top

melchiro wrote:
Hey Jim, no I did not drill out the slide holes.. These 750F carbs are as stock from honda, except my jet changes.. As for more vacuum with the pods on? I don't know..


So you did not raise the slide needle with a washer? Just the jet changes?

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--
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Shawn_Mc
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PostPosted: Sun Dec 08, 2013 3:44 am Reply with quote Back to top

If you understand how and what the slide holes do, you realize that there is a balancing act going on between them and the needle itself regarding the fuel metering.

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Jebbysan
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PostPosted: Sun Dec 08, 2013 3:51 am Reply with quote Back to top

Shawn_Mc wrote:
If you understand how and what the slide holes do, you realize that there is a balancing act going on between them and the needle itself regarding the fuel metering.


Very true....
These seem to respond with one idle screw washer as a shim....

Jebby

_________________
Ass, Grass or Gas....no one rides for free....
1979 CBX
1972 Corvette Stingray Coupe 406/4spd
1982 Z/28
2011 Silverado Crew Cab


"I don't do T and A...because I don't have much of either" Tea Leoni 
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magoogle
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PostPosted: Sun Dec 08, 2013 4:05 am Reply with quote Back to top

So should I shim my needles? I have cb900 carbs on my 750

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Shawn_Mc
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PostPosted: Sun Dec 08, 2013 4:28 am Reply with quote Back to top

magoogle wrote:
So should I shim my needles? I have cb900 carbs on my 750


The best way to tell would be (assuming everything else is in spec) to cruise along down the road in 4th or 5th at 4500-5000 for several minutes and then pull a spark plug and see how it looks. The needle is out of the picture at WFO and it isn't into the picture yet at idle or really low speed cruising. Cruising should show a plug thats light gray, not white, not black and sooty. Running with the choke on for any length of time and soot them up pretty quickly, so give the bike a decent 15 minute ride at a minimum while your playing with the carbs before you decide on an adjustment. If its unusually cold out, that'll play into your jetting significantly. IE, if you typically ride in 50-80F weather and you jet the thing on a 30-40F degree day, it'll end up too rich.

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magoogle
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PostPosted: Sun Dec 08, 2013 1:53 pm Reply with quote Back to top

Shawn_Mc wrote:
magoogle wrote:
So should I shim my needles? I have cb900 carbs on my 750


The best way to tell would be (assuming everything else is in spec) to cruise along down the road in 4th or 5th at 4500-5000 for several minutes and then pull a spark plug and see how it looks. The needle is out of the picture at WFO and it isn't into the picture yet at idle or really low speed cruising. Cruising should show a plug thats light gray, not white, not black and sooty. Running with the choke on for any length of time and soot them up pretty quickly, so give the bike a decent 15 minute ride at a minimum while your playing with the carbs before you decide on an adjustment. If its unusually cold out, that'll play into your jetting significantly. IE, if you typically ride in 50-80F weather and you jet the thing on a 30-40F degree day, it'll end up too rich.


Alright cool, rejetting today and gonna re-sync. Then I will take her out tomorrow. Snowing at the moment..

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oldschoolcarbs
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PostPosted: Sun Dec 08, 2013 7:06 pm Reply with quote Back to top

magoogle wrote:
So should I shim my needles? I have cb900 carbs on my 750


I'm the lonely voice of dissent where it comes to shims.

All too often other gremlins are at work—which is borne out by the sheer numbers of carb sets we see over the course of a year. I'd say that perhaps one in eight was shimmed by a well-intentioned mechanic and yet here they are on my workbench.

In every instance where I've encountered shims, without exception, they've gone straight into the trash and I've NEVER had a complaint that performance suffered. To the contrary in fact.

Not that I'm tooting my own horn because we're all capable of screwing the pooch from time to time, but numbers don't lie.

This isn't to knock an individual's skills as a home repairman, but there are things inside these carbs that are both easy to overlook and require specialized, hand-made (and in some cases prohibitively expensive), tools to properly service.

Take, for example, the accelerator pump circuit. It's not just about making sure that the individual nozzles are spritzing. Equally important is that the spray pattern is correct and uniform. If there's even the teensiest bit of crud accumulated around one outlet orifice it'll disrupt the pattern and you won't get the same output from that carburetor body as the rest.

Because it's aimed toward the throttle, it's exceedingly difficult to get to and the procedure has to be done with the utmost of care not to damage the orifice or you're in worse shape afterward than before.

The same is true for the pilot needle orifice. You'd be amazed at the amount of crud that can build up around the very tip of the needle, and because it's inside the bore you can't see it. So if all you do is spray carb cleaner through it, there's a chance that you're not going to get the same fuel/air mix between the individual bodies.

Likewise as well for the slow jet. Guitar wire? Please. Again, there can be so much gunk in the bore, never mind the orifice itself, that we have to use very precise tools to physically clear it out or run the risk of it re-clogging. (This cannot be done in situ.)

These factors account for a lot of DIY jobs, and even supposedly professional ones too, that either fail outright or fail to bring the bike fully back to life.

And people wonder what they're paying us, or any *competent* builder, for.

And it's not that we hold the key to the mystery of life. We don't do a single thing that an enterprising person can't do on his own given enough time, research, and a little dumb luck.

So, let's just make sure that everything is properly sorted before we apply questionable “fixes.”
 
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ivan_the_terrible
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PostPosted: Sun Dec 08, 2013 8:39 pm Reply with quote Back to top

Good, OSC. You surely know how to clean a carb,
and you routinely throw every shim away.
Now, what about "My carb jetting for Pods" ?
I am all ears. ...
Ivan
 
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Motocanada
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PostPosted: Sun Dec 08, 2013 8:52 pm Reply with quote Back to top

You know what, I don't understand this site at all. Everything OSC just said seemed polite, to the point, pertinent and well thought out. And yet he's getting called out here. And yet, that old grumpasaurus, the man who has single-handedly killed more threads than any person in the history of the world wide web, Sonicrete, his soul-crushing, absolutely disgusting diatribes on this site completely ignored. Indeed,in another section, he's being feted as the long lost king returned

How about you explain that to me, Ivan?
I am all ears....

Oh and Ivan, don't bother with the expansive knowledge and all that other crap usually trotted out. He hasn'thas an original thought since about two thousand and F'ing three.
 
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Jebbysan
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PostPosted: Sun Dec 08, 2013 9:27 pm Reply with quote Back to top

Motocanada wrote:
You know what, I don't understand this site at all. Everything OSC just said seemed polite, to the point, pertinent and well thought out. And yet he's getting called out here. And yet, that old grumpasaurus, the man who has single-handedly killed more threads than any person in the history of the world wide web, Sonicrete, his soul-crushing, absolutely disgusting diatribes on this site completely ignored. Indeed,in another section, he's being feted as the long lost king returned

How about you explain that to me, Ivan?
I am all ears....

Oh and Ivan, don't bother with the expansive knowledge and all that other crap usually trotted out. He hasn'thas an original thought since about two thousand and F'ing three.


If you knew the back story....it might change your point of view.

Jebby

_________________
Ass, Grass or Gas....no one rides for free....
1979 CBX
1972 Corvette Stingray Coupe 406/4spd
1982 Z/28
2011 Silverado Crew Cab


"I don't do T and A...because I don't have much of either" Tea Leoni 
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Motocanada
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PostPosted: Sun Dec 08, 2013 9:34 pm Reply with quote Back to top

On OSC maybe. On Soni, not even close
 
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genesound
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PostPosted: Sun Dec 08, 2013 9:47 pm Reply with quote Back to top

The thing that "professional" repairmen need to keep in mind is that they mostly see pieces that aren't running right. They don't have any idea about the other 250 guys with carbs that are running the shims without a problem, or whatever other unconventional fix of the day it might be about. It's really more about the tenacity, skills, intelligence, and daredevil (and a bit of luck) in the DIY'er than any supposedly hard "facts". If everything was known that ever would be, there would never be progress.

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Viton Valve Stem Seals
12.9 Cam Holder Bolts

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Last edited by genesound on Sun Dec 08, 2013 9:51 pm; edited 1 time in total 
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Motocanada
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PostPosted: Sun Dec 08, 2013 9:50 pm Reply with quote Back to top

Well said!
 
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Jebbysan
Red CB1100F
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Joined: Dec 08, 2007
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PostPosted: Sun Dec 08, 2013 10:10 pm Reply with quote Back to top

Motocanada wrote:
On OSC maybe. On Soni, not even close


The difference is that as hard as Bill is....I trust his info......
And it has nothing to do with personal feelings for either....
If I was a dickhead....would you still trust me?
Ok....don't answer that Laughing

Jebby

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Ass, Grass or Gas....no one rides for free....
1979 CBX
1972 Corvette Stingray Coupe 406/4spd
1982 Z/28
2011 Silverado Crew Cab


"I don't do T and A...because I don't have much of either" Tea Leoni 
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Motocanada
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PostPosted: Sun Dec 08, 2013 10:17 pm Reply with quote Back to top

Dera Jebby I will answer and you will understand

If you were knowledgeable and offering new thoughts but were a dickhead, I would hold my nose and not say anything.

If you were not contributing but polite and civil, well no harm is no foul

The problem is that Sonicrete has not added anything new, not one new thought in quite some while and yet he is a dickhead.

He DID contribute comething, say up till five or seven years ago, but currently He contributes nothing AND is a dickhead.

That is my objection
 
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Jebbysan
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Joined: Dec 08, 2007
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PostPosted: Sun Dec 08, 2013 10:22 pm Reply with quote Back to top

Motocanada wrote:
Dera Jebby I will answer and you will understand

If you were knowledgeable and offering new thoughts but were a dickhead, I would hold my nose and not say anything.

If you were not contributing but polite and civil, well no harm is no foul

The problem is that Sonicrete has not added anything new, not one new thought in quite some while and yet he is a dickhead.

He DID contribute comething, say up till five or seven years ago, but currently He contributes nothing AND is a dickhead.

That is my objection


I hear ya'.....but as much as he hates the search function himself....he usually ALWAYS answers questions...like it or not.....

Anyway....lets get back on topic......as a refresher......the 80 primary and 120 main seems to be a very good base line.....
It works for 750's and CBX's.....as they are similar in cylinder size and airflow.....
I know mine pulls well....just like Mel's video.....
BTW....the 80/120 with one idle screw washer was a recommendation by someone we all know....and has has a website and
books on Honda carbs.....his knowledge coincided with Mel's setup as well.....
So...sound baseline.....this is where we start!

Jebby

_________________
Ass, Grass or Gas....no one rides for free....
1979 CBX
1972 Corvette Stingray Coupe 406/4spd
1982 Z/28
2011 Silverado Crew Cab


"I don't do T and A...because I don't have much of either" Tea Leoni 
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Luckysox
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Joined: May 13, 2005
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PostPosted: Sun Dec 08, 2013 10:27 pm Reply with quote Back to top

Motocanada wrote:
Dera Jebby I will answer and you will understand

If you were knowledgeable and offering new thoughts but were a dickhead, I would hold my nose and not say anything.

If you were not contributing but polite and civil, well no harm is no foul

The problem is that Sonicrete has not added anything new, not one new thought in quite some while and yet he is a dickhead.

He DID contribute comething, say up till five or seven years ago, but currently He contributes nothing AND is a dickhead.

That is my objection
Name calling ?
 
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Motocanada
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PostPosted: Sun Dec 08, 2013 10:29 pm Reply with quote Back to top

I stand, humbly, corrected
 
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Jebbysan
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PostPosted: Mon Dec 09, 2013 12:09 am Reply with quote Back to top

I am a dickhead....and I am Canadian too Moto!....but fortunately most of you understand me Very Happy

Peace!
Jebby

_________________
Ass, Grass or Gas....no one rides for free....
1979 CBX
1972 Corvette Stingray Coupe 406/4spd
1982 Z/28
2011 Silverado Crew Cab


"I don't do T and A...because I don't have much of either" Tea Leoni 
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ivan_the_terrible
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Joined: Jun 27, 2011
Posts: 439
Location: Pesaro, Italy

PostPosted: Mon Dec 09, 2013 12:45 am Reply with quote Back to top

Motocanada wrote:
You know what, I don't understand this site at all. Everything OSC just said seemed polite, to the point, pertinent and well thought out. And yet he's getting called out here. And yet, that old grumpasaurus, the man who has single-handedly killed more threads than any person in the history of the world wide web, Sonicrete, his soul-crushing, absolutely disgusting diatribes on this site completely ignored. Indeed,in another section, he's being feted as the long lost king returned

How about you explain that to me, Ivan?
I am all ears....

Oh and Ivan, don't bother with the expansive knowledge and all that other crap usually trotted out. He hasn'thas an original thought since about two thousand and F'ing three.


Relax Moto, OSC doesn't need a lawyer here.
Sorry OSC, I didn't mean to be rude. You said you throw away every shims on your way.
I just wanted to know if you simply hate shims and maybe prefer clips,
or maybe you think there is simply no need in raising needles in this case.
Ivan
 
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genesound
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PostPosted: Mon Dec 09, 2013 2:17 am Reply with quote Back to top

My guess is that most of the time, the shims are put in because there is some other problem, probably dirt in various circuits, and maybe leaks. So, they're band-aids to fix misdiagnosed problems. Once the carbs are adequately cleaned, and are air tight around the shafts, insulators and such, then the stock Keihin needles usually work fine.

I think the best way to troubleshoot a problem as a new professional on the bike, is investigate into the issue with everything back to stock as possible, make it run right like that, and then change it from there.

If the guy that did the mods was truly sharp enough to do them right and get the tuning right, he should also be sharp enough to be troubleshooting it on his own, without turning it over to a pro.

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Viton Valve Stem Seals
12.9 Cam Holder Bolts

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Shawn_Mc
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Joined: Jul 30, 2012
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PostPosted: Mon Dec 09, 2013 2:41 am Reply with quote Back to top

ivan_the_terrible wrote:
Motocanada wrote:
You know what, I don't understand this site at all. Everything OSC just said seemed polite, to the point, pertinent and well thought out. And yet he's getting called out here. And yet, that old grumpasaurus, the man who has single-handedly killed more threads than any person in the history of the world wide web, Sonicrete, his soul-crushing, absolutely disgusting diatribes on this site completely ignored. Indeed,in another section, he's being feted as the long lost king returned

How about you explain that to me, Ivan?
I am all ears....

Oh and Ivan, don't bother with the expansive knowledge and all that other crap usually trotted out. He hasn'thas an original thought since about two thousand and F'ing three.


Relax Moto, OSC doesn't need a lawyer here.
Sorry OSC, I didn't mean to be rude. You said you throw away every shims on your way.
I just wanted to know if you simply hate shims and maybe prefer clips,
or maybe you think there is simply no need in raising needles in this case.
Ivan



Hazarding a guess...

The needles are matched to the "original spec" that the slide will move X amount given an air flow of X. As such and being a CV the amount of fuel being delivered by the needle is dependent on the vacuum. Unless you modify the slide (drill the holes larger) increasing the vacuum signal above the slide to raise it with less air flow, you really shouldn't have to do much with the needles, theoretically.

The secondary thought would be...its too lean to begin with, so raising the needle will help. Hard to argue if indeed the thing does indeed prove to be lean during cruise (which is where you'd want it lean anyway).

We've seen that the slide will open with zero air cleaner in the vid. Changing the main and pilot jets really doesn't affect that cruise area too dramatically (it does, just not drastically).

Anecdotal evidence would be riding the bike with the stock exhaust and no air box, it seems to run ok (mine did) but with an after market open style exhaust and no air box (pods or velocity stacks), suddenly (with no other changes) its wildly lean. Not a little, wildly. Its a case of 1+1= 6, jet sizes that is. At least on my bike it was that way. I had the VB56 1100 carbs with just a pilot and single main jets. I bumped the pilot one size and it made all the difference in the world. I never did change the main jets. Or mess with the needles, but I did find that the PO had shimmed them when I looked. I pulled the shims for a baseline and ended up leaving them out.

Im not going to tell anybody they're wrong because honestly...who cares? There arent any jetting police...if you mess around and find a setup that you end up liking run it. Or you could just sit on the couch and watch football I guess

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