The Spares Company
Club Shop/Regalia
Parent Website
Contact Officials
Machine Registrar
Club Secretary
Membership Secretaries
MPH Editor and Forum Administrator.
Section Newsletters
Technical Databases
Photos
Home
What's new
Latest activity
Forums
New posts
What's new
New posts
Latest activity
Information
Bike Modifications
Machine Data Services
Manufacturers Manuals
Spare Parts Listings
Technical Diagrams
Whitakerpedia (Vincent Wiki)
The Club
MPH Material Archive
Flogger's Corner
Obituaries
VOC Sections
Local Sections
Local Section Newsletters
Miscellaneous
Club Assets
Club History
Club Rules
Machine Data Services
Meeting Documents
Miscellaneous
Essential Reading
Magazine/Newspaper Articles/Letters
Adverts and Sales Brochures
The Mighty Garage Videos
Bikes For Sale (Spares Company)
Log in
Register
What's new
New posts
Menu
Log in
Register
Install the app
Install
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Air Fuel Gauge 02 Sensor Lambda Sensor
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Magnetoman" data-source="post: 108648" data-attributes="member: 2806"><p>I just finished modifying and jetting two Amal Concentrics for a Gold Star, requiring approximately 15 thirty-minute jetting runs totaling over 7 hours, covering ~200 miles, and resulting in ~160 pages of printouts of AFR data from my Innovate LM-1. At the risk of repeating a few things I've written before, some observations from this experience, in no particular order, are:</p><p></p><p>-- the bike "felt" like it ran fine for AFRs anywhere in the range ~10-15:1 so anyone who can <em>correctly</em> jet a carburetor by feel alone is a far better man than I.</p><p></p><p>-- watching the road while also mentally averaging the fluctuating AFR display and noting the throttle position would be hard enough, but to memorize just these two values for the at-least dozen throttle positions required to determine the full range of jetting is beyond my capabilities. Luckily, the Innovate LM-1 recorded the AFR, throttle position and rpm, freeing me to concentrate on potholes and possible sheriff's cars.</p><p></p><p>-- AFRs vary significantly depending on the conditions, e.g. accelerating up a hill, traveling on a level road, etc. This means that I actually needed more than a dozen readings to reliably determine the overall average shape of the AFR vs. throttle position curve for each configuration (hence the 160 pages of printouts).</p><p></p><p>-- because the AFR depends on conditions I will be adding an accelerometer to the "instrumentation package" in the future to make it easier to distinguish between AFR readings taken when accelerating, constant speed, or decelerating. In principle the rpm readings would be sufficient for this, but when analyzing 160 pages of data anything that makes the task easier is welcome. On this note, I can't imagine having done this without my Gerber Variable Scale and TI59 programmable calculator (vintage 1977) since I needed to normalize readings on the printouts from the throttle position sensor to the 1.56 V at full throttle.</p><p></p><p>-- it took a minimum of 15 sec. at full throttle while heading up a hill before the AFR stabilized at its final value. Attached is an example. I was going over 75 mph at the end of those runs which means during that time I covered ~1/4 mile. A shorter run reaching a lower speed would have given an erroneously high AFR reading. </p><p></p><p>-- at lower throttle settings the speed stabilized reasonably fast but I couldn't count on the AFR to stabilize until ~5 sec. had passed after I had reached that constant speed. Sometimes the AFR stabilized more quickly than this, but my default time at each throttle position was at least 5 sec. </p><p></p><p>-- a decade ago I measured a dozen new and used Amal jets of the same size on my flow bench and found 75% of them to be within +/-1 size of being correct. Unfortunately, the other 25% flowed too much or too little by as much as 3½ sizes. At one point when determining the jetting for the 1036 Concentrics I installed a jet marked <em>two sizes leaner</em> than the one that had been in it but the air/fuel gauge showed the nominally-smaller jet actually flowed a <em>half-size richer</em>. This was not the only time I ran into jet marking issues during this work. Keep this in mind if your jetting becomes too rich or too lean when changing to a jet whose marking makes it seem it "should" be correct.</p><p></p><p>-- wear or mis-manufacture of a needle jet by only 0.0005" is enough to completely wear out the jet (or make it too lean, if manufactured slightly too small). The needle jet in my Catalina Gold Star experienced that much wear during a 1200-mile ride so the needle jet definitely is not a set-and-forget component. As an aside, although the needle jet I used for my recent efforts is stamped <em>106'</em> I previously had measured a large number of NOS jets using two different calibrated bore micrometers and found them to be 0.1065". This is how they were originally listed by Amal. </p><p>[ATTACH=full]28231[/ATTACH]</p></blockquote><p></p>
[QUOTE="Magnetoman, post: 108648, member: 2806"] I just finished modifying and jetting two Amal Concentrics for a Gold Star, requiring approximately 15 thirty-minute jetting runs totaling over 7 hours, covering ~200 miles, and resulting in ~160 pages of printouts of AFR data from my Innovate LM-1. At the risk of repeating a few things I've written before, some observations from this experience, in no particular order, are: -- the bike "felt" like it ran fine for AFRs anywhere in the range ~10-15:1 so anyone who can [i]correctly[/i] jet a carburetor by feel alone is a far better man than I. -- watching the road while also mentally averaging the fluctuating AFR display and noting the throttle position would be hard enough, but to memorize just these two values for the at-least dozen throttle positions required to determine the full range of jetting is beyond my capabilities. Luckily, the Innovate LM-1 recorded the AFR, throttle position and rpm, freeing me to concentrate on potholes and possible sheriff's cars. -- AFRs vary significantly depending on the conditions, e.g. accelerating up a hill, traveling on a level road, etc. This means that I actually needed more than a dozen readings to reliably determine the overall average shape of the AFR vs. throttle position curve for each configuration (hence the 160 pages of printouts). -- because the AFR depends on conditions I will be adding an accelerometer to the "instrumentation package" in the future to make it easier to distinguish between AFR readings taken when accelerating, constant speed, or decelerating. In principle the rpm readings would be sufficient for this, but when analyzing 160 pages of data anything that makes the task easier is welcome. On this note, I can't imagine having done this without my Gerber Variable Scale and TI59 programmable calculator (vintage 1977) since I needed to normalize readings on the printouts from the throttle position sensor to the 1.56 V at full throttle. -- it took a minimum of 15 sec. at full throttle while heading up a hill before the AFR stabilized at its final value. Attached is an example. I was going over 75 mph at the end of those runs which means during that time I covered ~1/4 mile. A shorter run reaching a lower speed would have given an erroneously high AFR reading. -- at lower throttle settings the speed stabilized reasonably fast but I couldn't count on the AFR to stabilize until ~5 sec. had passed after I had reached that constant speed. Sometimes the AFR stabilized more quickly than this, but my default time at each throttle position was at least 5 sec. -- a decade ago I measured a dozen new and used Amal jets of the same size on my flow bench and found 75% of them to be within +/-1 size of being correct. Unfortunately, the other 25% flowed too much or too little by as much as 3½ sizes. At one point when determining the jetting for the 1036 Concentrics I installed a jet marked [i]two sizes leaner[/i] than the one that had been in it but the air/fuel gauge showed the nominally-smaller jet actually flowed a [i]half-size richer[/i]. This was not the only time I ran into jet marking issues during this work. Keep this in mind if your jetting becomes too rich or too lean when changing to a jet whose marking makes it seem it "should" be correct. -- wear or mis-manufacture of a needle jet by only 0.0005" is enough to completely wear out the jet (or make it too lean, if manufactured slightly too small). The needle jet in my Catalina Gold Star experienced that much wear during a 1200-mile ride so the needle jet definitely is not a set-and-forget component. As an aside, although the needle jet I used for my recent efforts is stamped [i]106'[/i] I previously had measured a large number of NOS jets using two different calibrated bore micrometers and found them to be 0.1065". This is how they were originally listed by Amal. [ATTACH type="full"]28231[/ATTACH] [/QUOTE]
Insert quotes…
Verification
What was Mr Irving's Christian Name?
Post reply
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Air Fuel Gauge 02 Sensor Lambda Sensor
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
Accept
Learn more…
Top