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PSI Jetless carb
(Click here to view the original thread with full colors/images)

Posted by: Garyb---------------------

Anybody try one ?
Might be the answer to the KTM jetting woes !

Posted by: Patman---------------------

You might try and rephrase your question to be a little more specific and then throw it out to Rich?

Posted by: shaggy829---------------------

I have not tried one on my bike , but i have held one in my hands and looked
it over very closely it is a very nice carb . Talked to Bruce the owner of Psi
for about 30 minutes needless to say i was very impressed with him .

Posted by: Badgas---------------------

Do you have a Web site address about the jettless carb?

Posted by: mxkid---------------------

There is another company selling jetless carbs called Atomized Fuel Technologies (AFT). They charge $275 for their carb, I think PSI charges $525 or $550 for their carb:scream: .

Hope this helps!!

RJ

Posted by: MXP1MP---------------------

We have gone over this before I asked a long while back I thought it sounded kewl myself. Then I was schooled by rich on it and it is just a waste of money!!!

Posted by: Jaybird---------------------

MXP1XP,
Why don't you share this schooling with us?

I have posted twice on this item and got zilcho on it. There apparently was someone who looked into this carb awhile back and at the time there was a problem with the adjusters not staying adjusted properly. I heard that PSI corrected this problem.
If you happen to know more than what we can find out here, let us know.
BTW....the Genisis BigAir is $575.00

Posted by: SFO---------------------

In the mods and performance forum they talked about the psi carb a while ago.
Eric ran one or helped someone who tried to make one work.
I believe that they found the carb worked not so well in the dirtbike environment.
Too dirty.
The snowmobile application was/is alot cleaner.
Man, if KTM's were jetted correctly everyone would have one. I think it is part of pride of ownership.
If you can jet it you can ride it. Kinda like being able to kickstart a stroker shovelhead.
If you can start it you can ride it.
Just surrender to the jetting gods and know you are not alone.

Posted by: aftcarbs---------------------

In regards to there being a problem with the adjuster assembly on the AFT HVV Carburetors:

I do not know how a problem could exist when the production carbs have not even been released yet. They are set to be released in 4-5 weeks. I would be interested where this information orginated. Please respond by email to Mike@aftcarbs.com

Thanks!

Quote:

Originally posted by Jaybird
MXP1XP,
Why don't you share this schooling with us?

I have posted twice on this item and got zilcho on it. There apparently was someone who looked into this carb awhile back and at the time there was a problem with the adjusters not staying adjusted properly. I heard that PSI corrected this problem.
If you happen to know more than what we can find out here, let us know.
BTW....the Genisis BigAir is $575.00

Posted by: Jaybird---------------------

For me, the interesting thing about the BigAir carb is the bore. Using the "V" slide, it has a small opening at low throttle...gaining flow as it opens to full 38mm. (they claim full flow comparable to a 39.5mm) With a bike like the 125sx, this may well be a means to have more low end stability without sacrificing top.

aaaa.....aftcarbs, do you see where I explained that I was talking about the AFT Carb having the problem? No? Funny, I don't either. Did you actually read what you cut-n-pasted?:think

Posted by: YZDezertGuy---------------------

Go get 'em JayBird! You tell that guy whose the boss this time!

Posted by: Jaybird---------------------

YZdesertguy,
I'm not trying to flame the guy, I know it's very easy to pop off here and say something stupid. Just the other day I had one thing on my brain and posted, although what was on my feable brain was not exactly what the topic was about.....think I heard about it? LOL...immediatley!

aftcarbs,
Please don't think I mean any ill towards you...I sure don't. I realize that your post was about 30 seconds after you registered here, so you get a by!

BUT....I DO have some questions for you, if you care to engage.

Posted by: weimedog---------------------

I would be curious to find out if either these jet less carbs could be used to solve issues with vintage bikes and their controlled leakers. (Bing's, early Mikuni's, and AMAL's) The price point of the AFT carbs make them a prime candidate as well as the history of some in that company.

I guess I would like to change the tone of this post a bit as I think there is a lot of potential in these things. My bet is the focus of the marketing organizations for both PSI and AFT are on new bikes and emissions. ( Snowmobiles and water craft as well) Wonder if there is enough vintage stuff happening to add that to the stack.

One of the things that is also of interest to me is the potential for more flexibility with altitude changes. I ride anywhere from 3000 to 10,000 ft above sea level. So anything to ease the jetting changes is of interest. Interestingly enough the only bike I have ever had that hasn't had a problem is my current VOR with its goofy Delorto. Is it the carb? Or is it the fact its a big bore four stroke? Pretty soon I will have to add the East Coast to the riding repertoire and this might be enough to push me over the edge and spend money in the direction of a jettless carb. (Not for the VOR...its OK)

My biggest concern is the process of getting different needle tapers. It seems that each application would need extensive testing with a feedback loop to those who can get needles with a different contuor to allow efficient development. That's the potential achillies heel to trying different markets and applications in my mind.

Posted by: aftcarbs---------------------

My apologies, but as it reads it could be construed as our carburetor had a problem and their's fixed it. No problem! Someone had reported that posting to us in the manner in which I responded. I am just a little protective of our product as we are currently working on some issues with PSI in regards to our patents.

As far as our product line and our applications, we have to start with the newest motorcycles and snowmobiles first, but as we get a little further along we be happy will work with customers to develop apps. for the older ones as well.

We have around 100 different metering rods for the different applications. With over thirty years developing the so called "Jetless Carb" we have a pretty good database of information to draw from. But we do welcome feedback from our customers and are constantly trying to make our product better.

Please feel free to contact me if you have any further questions.

AFTCarbs

Posted by: Rich Rohrich---------------------

Mike - How about posting a technical piece (i.e non-marketing fluff) about the design philosophy of the carb and it's connection to your original Lectron design?
The Advanced Technology forum here on DRN is setup just for that type of discussion and we welcome info from companies who want to take the time to share real technical details.

Posted by: 380EXCman---------------------

Ahhh the old Lectron...My dad had one on his race bike... A 78 TT500.. I seem to remember that it had a clear float bowl? and a flat slide?

Posted by: SFO---------------------

I thought Paul Gast bought all the Lectron stuff.
Is this still part of the same effort?
Is there a complete history of this design available?
It must work or people wouldn't still be trying with it.

Posted by: aftcarbs---------------------

History Behind the AFT Carburetor

Since the beginning of the combustion engine, man has had a natural desire to get as much power out of the wide variety of motors manufactured for work and play. For the past 37 years, William “Red” Edmonston has chosen the motorcycle as his passion for power and speed.

Red started racing Triumph motorcycles in the 1940’s and after 13 years of racing and breaking bones, he decided to move to California and work with Triumph as a road manager as well as open a Honda dealership to provide for his young family. During the 1960’s, Red continually became frustrated with the fuel delivery systems for the motorcycle industry. Most of the carburetors being manufactured and sold on motorcycles were complex to tune, and required a constant effort to keep tuned for proper operation of the motor. This was primarily because of the multiple and overlapping circuits (different jets for the differing throttle positions) that caused the air fuel mixture to be very rich at different throttle positions. These early carburetors could not adapt for altitude changes either, which added to the constantly differing air-to-fuel ratios and tuning problems. Besides the frustrations that many had with keeping their motorcycles running at optimum, these crude fuel delivery systems also cause the motor to run very inefficiently and with significant harmful emissions.

In the late 196o’s, after many years of racing, managing race teams, and selling motorcycles, Red began his long career of inventing, designing, and manufacturing carburetors for the motorcycle industry. In short, Red has had a significant impact on the motorcycle industry over the past 40 years. Red has held nearly 100 patents and has invented and manufactured nine different carburetors, each of which has shared some similarities while each subsequent model continually added improvements in functionality and performance. The history of the Red Edmonston’ carburetors spans many years and a great deal of experience and improvements:

· 1968-1969: The Lake Injector prototype and final production model carburetor.
· 1970-1971: The Pos-A-Fuel prototype and final production model carburetor.
· 1971: The Pos-A-Fuel with remote float bowl production model carburetor.
· 1973-1974: The Lectron prototype and final production model carburetor.
· 1976-1977: The E.I. Prototype and final production model carburetor.
· 1978: The Blue Magnum production model carburetor.
· 1980: The Bank of Four Blue Magnum model carburetor.
· 1981-1982: The Qwik Silver prototype and production model carburetor.
· 1982: The Qwik Silver Bank of Four carburetor wins Daytona super-bike race.
· 1993: The Qwik Silver II production model carburetor (sold to Edelbrock).

Red has always been intrigued by speed and power in the motorcycle industry and his insatiable desire to continually improve on the fuel delivery to the motorcycle engine has benefited a very long list of motorcycle enthusiast and racers. The complete list of racing careers that have been enhanced would be far too long to mention, but some of the more prominent names of racers that have won championships with Red’s carburetors include Kenny Roberts, Eddie Lawson, Freddie Spencer, Ricky Graham, and Doug Domokis.

With such a long history of invention successes and countless motorcycle world championships being won with Red’s various carburetors, one might think that Red would be content to finish his career on top with the sale of the Qwik Silver II to the well renowned Edelbrock Corporation. But fortunately for the industry, this is not the end of the story for Red Edmonston. Red’s passion for the industry has now brought him to his latest venture as part of Atomized Fuel Technologies Inc.

As the history and use of the combustion engine have changed and improved over the past decades, the majority of the mass production carburetor market for motorcycles has not. This has left many of the off-road enthusiast at risk of potentially loosing their rights for going out and enjoying the motor-sport of their liking. With the increasing world population, and the populations ever expanding concern for conserving our environment for future generations, a serious dilemma has emerged. Most Americans and Europeans prefer to live their lives with the philosophy “work hard and play hard”, and this quite often includes a motor-sport of one kind or another. The majority of the time, the best performing motors for off-road toys and performance vehicles is the two-stroke combustion engine. Though this motor tends to be high in performance and enthusiast’s enjoyment, it also tends to be extremely harmful to the environment because of all the harmful emissions produced by this rather simple and crude engine.

This has prompted many disagreements between the environmental groups and two-stroke vehicle manufacturers. In fact, the EPA (Environmental Protection Agency) was sued in 1998 by environmental groups for not acting quickly enough to regulate the emissions standards for recreational vehicles, especially as utilized on federal government owned land. The environmental groups won their lawsuit and the EPA is now required to provide sufficient proof of impending tightening regulations for the emissions produced by the recreational vehicle market.

The market that is about to feel the heat from these currently developing regulations is huge. There are over 22 million registered snowmobiles, watercraft, and two-stroke motorcycles in the United States and Canada. This market is currently relatively unregulated in regards to emissions standards and it appears there will be some retrofitting required of some of the current market to meet the imminent regulations.

In 1998, Red Edmonston saw this impending regulation as a threat to the industry he has lived his life so passionately to advance. So, being the eternal optimist and with his vast knowledge and experience in fuel delivery systems, he set out to develop yet another carburetor. This latest carburetor has one similar objective, more horsepower and torque than the originally equipped carburetors, but a new objective of also significantly reducing the harmful emissions from both two-stroke and four-stroke engines. Red and his son, Michael Edmonston (Michael also has a long list of motorcycle enthusiast accomplishments that include being the winning crew-chief of the 1989 Daytona super bike race), moved back into the Apple Valley building that had successfully housed the Qwik Silver manufacturing plant and began the research and development for the new HVV (high velocity venturi) carburetor.

After nearly a year of research and development, testing, changing and retesting, Red and Mike were finally ready to take their first two-stroke vehicle down to the CEE testing facility (the only California Air Resource Board – CARB approved testing facility) to have certified outside testing accomplished for their carburetors. This first test vehicle was a 1997 Honda CR250R racing motorcycle, which is an extremely popular and powerful off-road motorcycle. The results were very impressive and exceeded their expectations; with the AFT carburetor alone they were able to see a 50% decrease in harmful emissions and with the AFT carburetor and specially designed exhaust with a catalytic converter they saw harmful emissions reduced by over 85%. All this testing was completed by an independent testing agency and with the most stringent testing procedures. Along with this significant reduction in emission, the new AFT carburetor increased useable horsepower and torque by nearly 10% over the original stock carburetor.

Since accomplishing this first testing with the 1997 Honda CR250R, Red and Mike have also tested a 2000 Polaris 550RMK snowmobile and seen similar results as the first motorcycle tests. Now AFT is continuing application testing for other two-stroke vehicles and larger four-stroke cruiser motorcycles in its own Apple Valley dyno-room.

There are currently four patents or patents pending in relation to the new AFT carburetor. The two most significant new patents pending are the new oblong venturi shape that increases the velocity by the fuel needle and thus atomizes the fuel for a cleaner and more efficient burn, and the float bowl pressurization circuits that allow the carburetor to be completely altitude compensating for consistent low emission and enhanced performance at all altitudes without regard to the altitude of the motor during tuning. For more information on the simplistic, yet technically superior features of this new AFT carburetor, please read the “Technical Document” for this particular carburetor.

Since beginning this latest venture, AFT has established alliances with other companies that are attempting to help the industry via differing avenues. AFT currently holds a contract with Extengine that is working with a group of executives in China to help reduce emissions in their small two-wheel scooter/motorcycle market. China currently produces approximately 10 million of these scooter motors every year and is desperate to reduce emissions to an acceptable health level. AFT’s contract is to produce a small version of the current carburetor and meet European emission standards with their small scooters. Once accomplished, the Chinese group will be licensed to manufacture the carburetors for their scooters.

JT Granatelli Lubricants, Inc. is another company alliance entered into by AFT in the pursuit of preserving the two-stroke recreational vehicle industry. JT Granatelli Lubricants, Inc. is also very interested in helping the two-stroke and four-stroke market with a product that is both performance enhancing and emissions reducing. AFT has been helping the Granatelli company by utilizing newly developed two-stoke oil fuel mixtures in the AFT dyno room. The results have shown increased motor performance with the 1997 Honda CR250R when utilizing the Granatelli oil mixture with the fuel because of increased lubricity and lower emissions created by the Granatelli oil mixed with the fuel. AFT has also utilized the flow-bench to test Granatelli catalytic converters, which will likely be required for two-stroke motors in the future to meet ever restrictive emissions standards.

AFT has now tested their carburetor and exhaust system with the EPA in Ann Arbor, Michigan and is slowly getting the word out in the industry that having a two-stoke vehicle with acceptable emissions is within our grasp. Manufacturers have not been extremely receptive to having a small company such as AFT produce a product that improves performance and emissions over their own manufactured carburetors, but AFT will continue to work at educating the industry. The recreational vehicle industry is very large and there has yet to be any product that has come from the large manufacturers, two-stroke or four-stroke, that has come close to meeting both the performance and emissions reduction that Red has accomplished with the new AFT carburetor.

All the personnel at AFT strive to help the recreational industry, environment, and ultimately the recreational enthusiast enjoy the sport of their choice. With a little effort and American ingenuity, we can all enjoy “playing hard” and still save our environment for future generations!

Posted by: LoriKTM---------------------

Thanks for the info, Mike!

We'll take two-- KTM250MXC and KTM200EXC-- when can I place my order??!

Do you anticipate that buyers will need to use the Granatelli oil pre-mix in conjunction with the AFT carb for best results?

Posted by: Rich Rohrich---------------------

OH WELL, so much for the idea of a post with real technical info free of marketing fluff

I'm glad this is in YOUR forum Patman. :silly:

Posted by: Patman---------------------

Just letting 'em have a third swing at it.

Posted by: aftcarbs---------------------

Sorry for all the Fluff, but what do you expect we are proud of our product and it's accomplishments!!!! This should explain a little more about our carburetor.

AFT Off-Road Carburetor Technical Document

Atomized Fuel Technologies, Inc. has developed and is currently manufacturing carburetors for off-road motorcycles, ATVs, and snowmobiles. These carburetors have been proven to increase horsepower, torque, and fuel economy, while decreasing harmful CO and Hydrocarbon emissions. This document is provided to explain the technical design and functional aspects of the AFT carburetors.

· The design team of the “new” AFT carburetors have been designing and manufacturing carburetors for over 37 years and have incorporated many of the aspects of prior models into this newly enhanced, yet simplified carburetor. Some of these features are:
o Dual round floats that ride on individual guide rods. This float system has been proven to be superior to others because the floats are round and less susceptible to angle changes caused by vehicles being driven up or down hills or around inclined banks.
o Large capacity float bowl for increased capacity at higher throttle positions. The larger float bowl also helps alleviate susceptibility to vehicles traveling with significant angle changes based on topology.
o Dual Blade flat-slide design for reliability and better throttle response and velocity by the needle where the signal is needed.
o Single Circuit Metering Rod (needle) makes this carburetor extremely easy to tune. Because there are NOT any jets in this carburetor and the adjustments are made solely via the patented clicker mechanism that is accessed from the top of the carburetor. The metering rod, or needle, is raised or lowered in the venturi to provide a leaner or richer fuel to air ratio for the bottom third of the throttle position (there are 50 positions in this adjustment, which makes the tuning very precise). To adjust for a leaner or richer mixture for the top two-thirds of throttle position the metering rod is easily removed from the top of the carburetor and replaced with a different needle. There are 21 different needle grinds and increasing or decreasing the size of the metering rod/needle will either provide a leaner or richer mixture (4 sizes lower or higher is the equivalent of a single size jet change so this also allows for very precise adjustments).
o Unique high velocity venturi (HVV) shape increases the air velocity by the needle, which in turn creates more vacuum around the needle for increased response, torque and horsepower at low throttle positions. This feature also eliminates the need for an accelerator pump and gives more power throughout the power-band and increases power all the way through red-line RPMs. *Patent Pending on this venturi shape design.
o Altitude compensating pressurization circuit is accomplished by the unique plenum at the front of the carburetor venturi mouth. Inside this plenum are two air circuits that internally pressurize the float bowl with the exact same atmospheric pressure that is passing by the metering rod/needle. This pressurization plenum was created to allow the pressurization of the float bowl without creating the undesirable reverse pressurization that can occur at high throttle position by installing a hole or tube for the pressurization circuit directly in the mouth of the intake venturi (the air flowing through the venturi and past a tube or hole that is directly in the venturi will actually draw air and possibly fuel out of the float bowl at high throttle positions because of the same venturi effect that is caused around the metering rod/needle). Because of the carburetors unique single circuit fuel system and the lack of fuel jets, this feature allows the carburetor to automatically compensate for altitude changes. *Patent Pending on this float bowl pressurization design.
o Double tube enrichment and high idle circuit. By pulling out the choke, the internal circuit for immediate enrichment and delayed high idle is engaged. This circuit includes a double walled tube with jet-sized holes in the bottom and in the side near the top of the float bowl. While the carburetor is not in use, both the inner and outer chamber of this tube is gravity filled with fuel. Once the vehicle is started, with the choke cable pulled, the fuel in the inner and outer tubes will be channeled into the carburetor throat behind the slide. The initial fuel from the outside tube will serve as an enrichment method for starting purposes. Once the fuel in the outer tube has diminished, the fuel will continue to be delivered only through the jet-sized whole in the bottom of the tube. This fuel will be mixed with air that is now being delivered through the hole in the upper part of the outer tube, which being delivered behind the slide will provide for a high idle until the choke cable is pushed back in and the circuit is closed.
· AFT has incorporated the best of the carburetor designs over the past 37 years of carburetor design experience of Bill “Red” and Mike Edmonston while reducing the amount of actual parts and complexities of the carburetor. This carburetor is very easy to install and tune, as well as being attractive to the eye.

AFT has created a performance enhancing carburetor (generally an eight to fifteen percent increase in horsepower and torque), as well as keeping an eye toward atomizing the fuel to create a powerful and clean burn. This carburetor has been tested with the California Air Recourse Board (CARB) testing center, CEE, as well as with the EPA in Anna Arbor, Michigan and has demonstrated a 50-55% decrease in harmful emissions on a Honda CR250R motorcycle and Polaris 550RMK Snowmobile by solely changing out the carburetor. With a specially modified exhaust pipe (a two-stage catalytic converter installed), the emissions were reduced by 80-90%, while still maintaining an increase in horsepower and torque of approximately eight percent.

AFT is continuing to run application testing as well as emissions testing in our own dyno-room, equipped with a Superflow SF600 flow-bench and SF240 Cycledyn EDI-current dyno, and look forward to providing increased performance and emissions reduction for the ever-expanding two-stroke and four-stroke recreational vehicle market.

Posted by: Rich Rohrich---------------------

Nice press release Mike, but this ISN"T Motocross Action so glossing over technical stuff isn't what we had in mind.
Nice job of cut and paste from your website though:D

Posted by: KiwiBird---------------------

Re the altitude compensation - does this circuit adjust for humidiity too or does that require manual adjustment?

What happens to the gas if (OK, WHEN) the bike is upside down as there seems to be no drains out of the carb?

Posted by: aftcarbs---------------------

Unfortunately, the carburetor does not adjust for humidity, only altitude. The passages to the venturi have a one-way valve eliminating the possibility of fuel overflow. Good questions though!!

Posted by: 380EXCman---------------------

Would'nt adjusting for humidity and altitude use the same adjustments anyway?

Checked out the website....Those are some very pretty pieces..... Nice shop looks very clean and state of the art...

Is there one available for Husabergs? I have no complaints :D about the carb on my new berg other than it is big, ugly and corroded and it does seem to be very sensitive to elevation changes... It works great at the elevation I ride at 95% of the time but when I start to climb it gets rich real quick...

I like to walk around the pits and whack the throttles open on all the YZF's so its nice to know I can do it to my own and it starts first kick each time

Do you need a "Don't touch my throttle" sign to hang on the bike with the AFt carbs?

Posted by: aftcarbs---------------------

There is a difference between altitude changes and humidity changes. Altitude is a difference in pressure and oxygen content, humidity as we all know is moisture. Because the carburetor balances the pressure between the fuel delivery point in the venturi and the pressure on top of the fuel, it stays in balance. Other carburetors use inadiquate atmosperic presurization on top of the fuel causing an unbalance as the pressure changes. Humidity or moisture displaces fuel therefore creating a lean condition under extreme humidity conditions. Hope this helps.

Posted by: Rich Rohrich---------------------

Quote:

Originally posted by aftcarbs
. Humidity or moisture displaces fuel therefore creating a lean condition under extreme humidity conditions. Hope this helps.

Mike - Humidity displaces fuel? These are SMART people you are talking to out here, they can spot someone blowing smoke from a mile away .

The effects of humidty tend to vary with temperature. High humidity with low to moderate temperatures (say below about 50) will tend to make the engine run a bit rich, but the effect is pretty minimal. While high humidity at high temperatures will cause rich running and a loss of power.

Why a difference? It has to do with the saturation pressure associated with specific temperatures. Basically when water is a vapor in the air it exerts a pressure that becomes part of the total atmospheric pressure. So lets say it's your basic Chicago day in July it's 100 degrees (F) and it's 100% relative humidity . Because we are at 100% humidity it means we've reached the point where no more water will evaporate into the surrounding air (i.e the saturation point. That water vapor in the air will exert pressure (it's a gas now) of 1.93" hg. So if we have a barometric pressue reading of 29.00, only 27.07" hg will be exerted as AIR pressure. The lower density air would require less fuel to hold our air/fuel ratio at best power 12.5:1

If we left every thing else the same but dropped the temperature to 60 degrees, the water vapor would only exert a pressure of about 0.5" hg, so our actual air pressure would be 28.5" hg. The available air density would be MUCH higher at this temp. Higher density air means we need more fuel to hold our air/fuel ratio at best power 12.5:1

For a given temperature, as the relative humidty goes up the air pressure we can use to make horsepower goes down.
Basic rules HOT and HUMID lean it out a lot, Cool and humid MAYBE lean it a little. But keep in mind as the air temp goes up the ignition delay period is reduced and engines become more knock prone, so tread lightly.

Keep in mind I generalized the hell out of this for the sake of clarity, but hopefully you see the basic connection. I really think this is easier to understand than it is to explain

Automatically compensating for these changes without the use of some type of absolute pressure sensing/feedback device would be fairly tricky.

There are standard charts for relating relative humidity and temperature to pressure for those of you who want to play around with this stuff. A lot of good drag and road race tuners use baro, temp, & humidity to form a density altitude (i.e pressure) value to tune from.

The ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) is a good starting point if you want to really learn the science of this stuff. http://www.ashrae.org/ . Aviation sources will have similar info.

Posted by: weimedog---------------------

SO what about the Edelbrock product offering? Where does that Quicksilver jetless carb fit in? Is it the old Lectron? How does the new products from AFT and PSI improve on that design?

Posted by: Okiewan---------------------

Who's being defensive?

1) Someone comes in a pastes in press releases.
2) Someone questions it.

Something wrong with that? If you step up to the plate, be willing to swing the bat.

380 has it all figured out... the best way to be the blue thumpers, lol.

Posted by: bwalker---------------------

AFT, I could be crazy, but I always thought the reason for a two cycle motor high emmissions was caused by its use of loop scavenging. IMHO there is no way a fancy carb is going to change that.This whole thing reeks of some Naderite claim that Detroits had a 100 mpg carb for years that they have been holding back.

Posted by: cr-man---------------------

AFT you don't have any testimonials on your dirtbike carbs? Also Kawasaki used a Venturi design similar to yours in the 80's called a keyhole design and it did not work very well they did away with it the next year I believe. Also according to your dyno charts with your carb and the exhaust you lose a lot of power up until you reach the very top what good is that? We want answers here not press releases and if your not willing to give answers to our questions you won't sell anything here!

Posted by: bwalker---------------------

IMO the original Lectron was garbage for a two stroke app. I spent two winters trying to get a set to run right on hill climb sled. They may be great for a fourstroke drag bike, but for a two stroke that sees big throttle transitions they leave A LOT to be desired.

Posted by: CC_RIDER---------------------

Quote:

Originally posted by Rich Rohrich

Mike - Humidity displaces fuel? These are SMART people you are talking to out here, they can spot someone blowing smoke from a mile away .

Rich, I trust it was under great duress that you edited your original statement.

Quote:

originally posted by Okiewan

Who's being defensive?
1) Someone comes in a pastes in press releases.
2) Someone questions it.
Something wrong with that? If you step up to the plate, be willing to swing the bat.

Did we miss a post here?

Quote:

originally posted by bwalker

...the reason for a two cycle motor high emmissions was caused by its use of loop scavenging. IMHO there is no way a fancy carb is going to change that.

I agree. I would like to read their research work and analysis of how this is accomplished, but of course that would be heavily guarded information.

Posted by: Rich Rohrich---------------------

Quote:

Originally posted by CC_RIDER
Rich, I trust it was under great duress that you edited your original statement.

Originally I was trying to be polite because it was in Pat's forum. I feel no such compulsion when BS gets transferred into this forum.

FOR THE RECORD, high humidity ( % moisture in the air) DOES NOT displace fuel and DOES NOT cause engines to run lean. My follow-up post CORRECTLY explained the effects of humidity on spark ignition internal combustion engines.

My tolerance for BS from manufacturers is normally pretty low, when someone shovels it into MY yard it tends to tick me off. My expectations from THESE guys is fairly high so it's doubly disappointing.

Posted by: John.T---------------------

Umm Rich what's the deal here? You seem to have good knowledge on this topic, and mike seems to also, but I am confused I mean (no offense) but this guy makes these carbs so does he not know what he is talking about? Or are these carbs really no good, and that's what you are telling us? Just kinda elaborate for the less technical people like myself (I probably could not afford this carb anyways, but I would like to know what the real deal is)
thanks:D

Posted by: Rich Rohrich---------------------

In spite of his famous surname Mike posted some complete nonsense in his reply to a technical question and I called him on it. You don't have to know how to build a carb to know how and why humidity effects the fuel curve. If you aren't convinced that my response was accurate I provided a reference source for further investgation. I DON'T EXPECT anyone to take my word for things out here, so I try to provide backup whenever possible.

Unfortunately everything else Mike posted so far was marketing fluff. He is more than welcome to tell us all the technical details of the AFT carbs, but if he posts incorrect info someone out here is going to call him on it. I just happened to get there first.:confused:

DRN - Where sacred cows are killed and eaten

Posted by: John.T---------------------

Oh ok thanks Rich!:D I was not sure if he was posting incorrect info, or just trying to play us as idiots, or If he was even Mike! I was lost!! But thanks for setting him straight! Ill take your word for it because you seem like you know your stuff and you can back it up too! Wow what a thought huh
:confused: I hope mike will come back and defend his point or at least explain how he made an error

Posted by: aftcarbs---------------------

Look! No one was trying to post "Press Releases", AFT apologizes for the general information that was posted about our company and carburetors. It's hard to know what level you need to communicate at when you new to any kind of public forum such as this. There's no need to be hard on Rich either, he is doing his job and he seems to be quite knowledgeable. But things are not always as they are printed in books and technical papers. Sometimes this information can be false when dealing with applications different than they are intended. not that what he says is not true , because if I read the same information he did I would probably respond in a similar manner. Regardless, maybe my answers are a bit simple, but not everyone is of Rich's expertise. for those who are we will provide a much more technical explanation of our carburetor in the near future, but I will QUICKLY answer some of the other questions.

I can only speak about the AFT carburetor in comparison, but the QwikSilver is a pretty good carb. The only real similarity is the single fuel system. The biggest difference is the venturi shape. They use a round and sometimes an oval but not the "Egg" or "V" shaped that is found on the AFT. The QwikSilver also uses a fuel bowl breathing system that is better than most but still not adequate enough to get enough pressure on the top of the fuel (I explained why that is important in an earlier post), especially at throttle positions above 1/3. The AFT carburetor uses the standard cable through the cap into the slide for throttle valve operation and the QS uses a leaf spring linkage set-up. This makes for a stiff throttle, bigger carburetor and more components to wear out. Another difference is the metering rod adjustment mechanism and metering rod grinds and tolerances. The AFT carburetor uses an new and improved adjuster along with new metering rods to take full advantage of the venturi shape. The AFT carburetor uses a float and needle and seat from a Mikuni, so parts are very accessible and their performance is proven. Those are probably the biggest differences.

Kawasaki did use something similar venturi shape, but not in conjunction with a single fuel system. Having the extra velocity at low speed allows the the single fuel system carburetor to react much faster, and because the single fuel system metering rod design lays fuel in at the top of the air it provides better atomization of the fuel (a smaller micron particle of fuel). A multi-circuit carburetor(which the Kawasaki carburetor was) has a tendency to have rich spots at each circuit overlap and because of the way fuel is introduced to the air stream it has a much higher micron size. The key to our cleaner emissions is in the atomization of the fuel/oil to make it simple. Please keep in mind this a very "dumb" explanation of this but I think it gets the point across. Sorry if I have offended anyone!

As to the loss of midrange in the carb and exhaust dyno charts, this is attributed to the exhaust pipe design. We are working with some exhaust pipe manufacturers to correct this loss. But the real key to those results is in the reduction in Hydrocarbons and Carbon Monoxide. As for their validity, all tests were performed at an independent test lab "California Environmental Engineering" and were then performed again in February, 2001 at the EPA in Ann Arbor, MI with the same results. Also keep in mind that all off-road/snowmobile information posted is all emissions related. We are working on the website to include information that pertains to configurations geared specifically for performance results.

Hey we are trying our best to keep 2-stroke and 4-strokes alive. We may not have all the answers, but we are constantly learning new things everyday and we others will do the same. I hope I have answered most of your questions, but if I missed any please feel free to e-mail me at Mike@aftcarbs.com

Thanks for the intelligent responses, this is a good forum and I hope myself and AFT will be allowed to contribute more in the future.

Rich,

Please keep in mind we will provide more technically detailed information in the near future. Thanks for your input and keep up the good work!

Posted by: Rich Rohrich---------------------

Quote:

Originally posted by aftcarbs
Sometimes this information can be false when dealing with applications different than they are intended. not that what he says is not true , because if I read the same information he did I would probably respond in a similar manner.

You're a tough one to figure out Mike.

I can't tell if you are being condescending or ...
So I'll take the high road and ask nicely to have you explain to me and everyone else how

Quote:

Humidity or moisture displaces fuel therefore creating a lean condition under extreme humidity conditions

I've abviously been doing it wrong for the last 30 years, so I'm looking forward to gaining an additional edge in my tuning.

Quote:

Originally posted by aftcarbs
Rich,

Please keep in mind we will provide more technically detailed information in the near future. Thanks for your input and keep up the good work!

Mike - I look forward to it, as do the rest of the DRN faithful. I'm happy to see you realize this isn't personal. Having you here I know we've tapped into a good source of information, and we're going to drag it out of you one way or another.

FWIW, I've always found it useful to assume that the people reading posts in this forum are looking for the most technically indepth information we can provide. Given the overall advanced technical level of DRN members as a whole it's proven to be a pretty safe approach. The folks who need clarification will always ask, so don't be shy about being too technical out here. Given the watered-down crap masquerading as tech in the magazines we try to make this place a where people can come for quality technical info. Sometimes peoples heads will hurt from having to think too hard, but that's a damn sight better than that pre-chewed pseudo-tech BS in the dirtbike mags.

Consider this an open invitation to come out here and make our heads hurt

Posted by: HONDA65---------------------

Seems to me that this thread has varied away from the original question, IE: has anyone tried the PSI carb? I've been waiting also, to no avail. So I'll tell you. PSI's west coast branch was kind enough to let me demo one for 3 weeks. I've tried it twice now, and so far have been some what impressed, but not overwhelmed. After alittle bit of dialing in, it ran clean and consistent all day. I ran my stock pipe and silencer, for a baseline standard. I'm not sure that it added any horsepower, as they claim, but once I got it running smooth, I left it alone.

Yesterday, I tried it with a FMF Fatty and silencer(shorty), I experienced some pinging, which I would also get with the stock carb and this setup. (by the way, I'm also running pump gas at this point as well.) In the time that I had, I was unable to get the pinging all the way out of it, but it did seem to pick up aliitle more power, more then with the stock carb and the FMF. I'm going to go test it once more today, then I need to decide whether to keep it or send it back.

From what I can see, if it does increase power like they claim, it is in the mid to top, but not much of an increase on the bottom. But I'm going to take both carbs and do a back to back comparison. I'll let you know.

Posted by: Rich Rohrich---------------------

Quote:

Originally posted by HONDA65
Seems to me that this thread has varied away from the original question, IE: has anyone tried the PSI carb?

Other threads have covered the results people had with the PSI carbs. In a nutshell:
- Sticking slide problems
- Trouble getting good response in transition on MX applications
- Flat bottom and mid in exchange for top end
- Overall finicky jetting

The carb was originally designed for sleds where some of these problems can be masked via clutch tuning, but MX apps seem less forgiving. I hope your luck is better.

Posted by: HONDA65---------------------

Rich, I tried to find previous threads on this subject, to no avail. However, I've now come to my own conclusion. After another full day of testing, I agree with everything you said (except the sticking throttle, thank God). I put back on the stock carb, and it ran better everywhere. I thought the PSI was alittle better, but testing them back to back showed that it wasn't. Maybe with some more time? Oh well, at least they let me try it first. I'm only out the shipping.

Posted by: Rich Rohrich---------------------

Quote:

Originally posted by HONDA65
Oh well, at least they let me try it first. I'm only out the shipping.

Too bad more companies don't take that approach

Posted by: olderndirtmom---------------------

Anyone care to update the history of this technology, as well? It's history day on DRN. A very cursory scan of the net makes me thinks this didn't take off.?? (My apologies if I'm missing the obvious viewing thru Google-lenses.)

Posted by: kmccune---------------------

Want to hear a good one....
I came across this post, while searching for a carb for my airplane project... go figure

Kevin

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