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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769089 03/24/19 9:05 pm
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We did change the spray tube also to an uncut 4 stroke type on the Gold Star.

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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769094 03/24/19 9:43 pm
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End of MK11 doc by John Healy, air jet gets a mention.

"It is interesting to note that there is another air bleed located at the middle of the front of the carburetor. By varying its size one can increase or decrease the vacuum produced by the venturi effect. It will affect the fuel delivery through the needle jet across most throttle openings. The size of this air bleed is a compromise and is seldom altered. "

Bearing in mind that I am normally wrong, here goes anyway. 2 strokes breath twice as much as 4 strokes, this must make big differences in setting up jets for same size chokes. I have never messed around with air jets, but, your plan to drill and plug with options seems like a reasonable one. So long as they are easy to change, is there enough meat to tap a thread for screw in jets?

Thinking out loud bearing in mind JHs quote above, if you open up the air jet that will dilute the venturi signal and make less signal at the needle jet, weakening the mix compared to a smaller air jet? Or have I got this back to front?

Last edited by gavin eisler; 03/24/19 9:57 pm.

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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769099 03/24/19 10:06 pm
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Originally Posted by RPM
We did change the spray tube also to an uncut 4 stroke type on the Gold Star.
Did you use a spray tube from a 600/900 Concentric? I believe it was Kerry W who in an earlier post in this thread pointed out a 1036 was used on the last of the Velocette Thruxtons. An AMAL book shows that indeed it was, with a note in the "Special Details" column saying it has a 1034/070 Air Tube. I haven't been able to find that part number listed elsewhere yet but it's tempting to think it means spray tube. However, that same column lists either 'air tube' or 'spray tube' for various other carburetors so it's not clear they mean the same thing.

Originally Posted by gavin eisler
End of MK11 doc by John Healy, air jet gets a mention.
I should have said that he doesn't discuss the "air jet" in the Mark 1, i.e. that 3/16"-dia. tube running from the front that has a constriction in the 2-stroke 627 and 1036/1038.

Originally Posted by gavin eisler
if you open up the air jet that will dilute the venturi signal and make less signal at the needle jet, weakening the mix compared to a smaller air jet?
Exactly.

If any of you, too, ever become obsessed with the issue of spray tubes you will find that some people have written they believe a non-cylindrical tube decreases the relative pressure difference at the outlet (which would weaken the mixture), while other people believe it increases the relative pressure difference (richen the mixture).

Rather than belief, if I had examples of at least three of the four spray tubes in carburetors of identical bore I could put them on my flow bench and measure the pressure under identical flow conditions to obtain actual data to answer this. I have the instruments to measure pressure differences with a resolution of 0.001 psi which certainly should be sufficient.

It happens that I already have a 932 Concentric with a Norton spray tube. A little research found that a 932 also was used on some BSA 650s and on the B50MX, presumably with flat-cut spray tubes, as well as on a number of Bultaco and other 2-strokes. A little more research showed that if I waited long enough for them to turn up on eBay and was willing to spend ~$150 I could buy the "missing" two carburetors in order to conduct this experiment.

The thing is, I don't want to spend $150 of my own money to get these carburetors and then spend the time making measurements to answer a question that should be of general interest to more than a few others. So, I'm proposing to crowdsource this experiment. If someone(s) else is/are interested in having the answer, send those two missing carburetor bodies to me (flat top and slant-cut spray tubes). PM me for the address if you want to send the carburetor(s). Feel free not to take the time to disassemble anything, but all I actually need are the bare bodies as shown in the photograph. I would swap the same slide, cap and jets between the bodies for the measurements so the only the spray tubes would differ. If a few of you are interested enough in knowing the answer to send worn-out bodies to make the measurements happen, that's great. If not, that's OK too.

Attached Files Concentric_Norton.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769106 03/24/19 11:42 pm
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I use a Norton 850 932 carb on a ported to match B44 fitted with B50mx cam, kept the stepped spray tube and matching needle. After tuning the main jet it runs cleanly through the rev range and throttle openings.

Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769131 03/25/19 2:09 am
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Yes both wanted the same except the main, Now i did not spend lots of time making sure the pilot was spot on since it was a race bike. The street bike idled and started very well with the
30.

The spray tube is the same for the 900 and 1000 series. I usually push one out of an old 900 series carb and put it in the 1000. I have never tried to get a new one. they shouldnt wear.

As for Power.
The last race engine was 9:1 with big cams, lots of head work, pearson crank. single plug was 41 hp at 7k still Climbing. This was with a 1038. I have checked the GP and they are worth about 2- 2.5 hp over the 1038. Only at the very top, the 1038 works great everywhere else!!

As for the street bikes, the most with a stock muffler make 26-29, and with aftermarket straight thru muffler are 31-32.. i have a original BSA muffler that i need to try, I have a feeling the
new repro mufflers are not made for performance these days!!

All interesting stuff!!!
Let us know what jetting you came up with!! and how you like the carb !!

Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769149 03/25/19 9:30 am
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My 1038 experience has not been great, When I got the bike it had a brand spanking new carb that hesitated slightly when opening the throttle off idle, not badly but enough to be annoying. I looked into the jetting and eventually worked out it had the 2 stroke setup, angled spray tube, with 3 1/2 slide 107 needle 30 pilot the needle is stamped 0 and 380 main. I decided to change to the 4 stoke setup. got an uncut spray tube (incidentally off a 932 that had lived happily on my Norton Commando for years) I bought the AMAL conversion kit numbered 622/235 consisting of jet holder , 106 needle jet and needle 622/124. It now runs far worse. I got myself an AFR meter and put the sensor into the front end of an old muffler. I can get it running a smooth Idle at 14:1 AFR but as soon as I open the throttle it runs rough and goes full lean on the AFR meter. Unfortunately I haven't really had time to really get stuck in and try tweeking things I only get 1/2 hour here and there to spend on it

Last edited by geordie; 03/25/19 9:44 am.

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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769165 03/25/19 12:58 pm
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"At first I thought it was Celtic for 'President'", spat my coffee out, Laugh of the day for me.

No less an authority than Rupert Ratio thinks that slash cut spray tubes are richer than flat tops, its the only reference I have handy, I had a good 2 stroke tuning book that covered carb details , but i lent that to someone and it never came back.


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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769186 03/25/19 4:24 pm
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Originally Posted by kommando
I use a Norton 850 932 carb on a ported to match B44 fitted with B50mx cam...
Originally Posted by JakeH
Let us know what jetting you came up with!! and how you like the carb !!
As shown in the first photograph, some years ago I modified a "universal" probe sold by Innovate Motorsports to go with my Innovate LM-1 air/fuel meter in order to make it suitable for motorcycles. However, the probe has two limitations, one more serious than the other. The more serious limitation is that baffles can keep the probe from being inserted very far in some exhausts. The less serious limitation is that, especially with cams with a lot of overlap, fresh air is sucked some distance up the pipe every other revolution which would otherwise invalidate the readings. To overcome this I made a "Bunsen valve" from high temperature silicone material that wraps around the silencer, opens to let exhaust out, but closes when the pressure drops to keep air from being sucked in. Still, the silicone material flaps in the breeze so it isn't suitable for really high speeds or for long distances.

Anyway, in thinking about working out the optimum jetting with my 1036 and 1038 Amals I realized I have another choice for attaching the air/fuel sensor to Gold Stars. Part of my hoard of BSA parts is a Gold Star pipe to which a homemade megaphone had been welded, shown in the second photograph. By cutting the megaphone off and welding a bung for the sensor I can use this pipe on any of my three Gold Stars with their three different silencers.

I have an original Innovate LM-1, made in the dark ages of limited data storage, so it "only" can collect data for 44 minutes from 5 inputs at 12 Hz. I have it configured to collect air/fuel, rpm, and throttle position. The latter by means of a "universal" bracket and potentiometer that I friction couple to the throttle. Rotating the throttle between closed and WFO a few times with the engine off establishes the voltages corresponding to the throttle extremes.

Innovate's current model LM-2 records at the same 12 Hz as my LM-1, although it can record 32 channels vs. only 5 for my LM-1. However, this isn't of any use to me since I only use 3 channels anyway. LM-2 data is recorded on a 2 GB card so presumably recording time is longer than the 44 min. of the LM-1, but I haven't found that time to be any sort of practical limitation. If I ever decide I have to fully instrument the V-8 in a Boss Hoss I'll have to upgrade to the LM-2, but the LM-1 should continue to do nicely until then.

Originally Posted by geordie
3 1/2 slide... got an uncut spray tube... as soon as I open the throttle it runs rough and goes full lean on the AFR meter.
Originally Posted by gavin eisler
No less an authority than Rupert Ratio thinks that slash cut spray tubes are richer than flat tops,
No less an authority than Stoor Regan emphasized the need to "Trust, but Verify," but taking this at face value the problem geordie is having may be fixed with a #3 slide. If his replacement uncut spray tube did indeed weaken the mixture that, plus the weaker #3.5, could be what is causing the behavior when the throttle is first opened.

The 1970 Thruxton used a R1036/4, presumably with 4-stroke spray tube, with 320 main, 30 pilot, .106 needle jet, needle on position 1, and #3 cutaway. These settings should be pretty close to what are needed on a Gold Star.

Tying up one loose end, I heard back from Burlen/AMAL today confirming that all series of Concentrics, including those of the Mark 2, use the same 622/074 4-stroke spray tube. Still open is the question whether the air passage should be 3/16" all the way. I sent a subsequent question to Burlen about this but haven't received an answer yet.[*] Given that it is unlikely they produce that particular carburetor it's possible no one at the "new" AMAL will know the answer.

[*]I've now heard back with an answer to this question. All of the 1000-Series bodies were made in Spain and they only have one machining drawing for the body. It shows a 4.75 mm (0.187") air passage that reduces to 2.5 mm (0.0984") near the far end.[**] The email says the 1036/001 body number also was used by Maico and since had the body been modified for Velocette it would have a different part number he speculates that the air passage dimensions were the same for both. This makes sense since, as they say, beggers can't be choosers and by 1970 Velocette was in no position to insist on much of anything. According to Ivan Rhodes's book, only 140 Thruxtons were made in 1970. So, my speculation is that if Velocette could have had carburetors made that provided optimum performance on the Thruxton they would have had that passage drilled 4.75 mm the entire distance. Instead, they had to make do. But, that's speculation that can't be checked. In any case, I'll proceed to try to determine the best possible jetting without drilling out that passageway.

[**]I previously wrote that I found the restriction to be 0.082". In light of this recent email from AMAL I remeasured the passage in the 1038 and found some machining swarf at the end was causing a restriction. With the swarf pushed out of the way a #41 drill bit (0.096") goes through the passage but a #40 (0.098") does not.

Thruxton Addendum: Thruxtons used 1-3/8" (35 mm) AMAL GP carburetors during 1965-68, oddly dropping considerably in size to 930 Concentrics for 1969, but then back up to 1036 for the final year 1970. In his book 'Velocette' Rod Burris says "The last few Thruxtons to trickle out were fitted with Concentrics, although whether this is due to the infamous 'loss' of a large batch of new GPs is uncertain." Maybe the "infamous 'loss'" is described elsewhere in the book, but GPs were considerably more expensive than Concentrics so a company on life support might not have had the funds to recover from a major theft. Also, the drop in size all the way to 930 makes me wonder if there was no available stock of 932s they could substitute by the time the theft was discovered.

I would have thought all 360 cc Bultacos would have been users of the Spanish-made 1000-Series but, with the exception of the TS350 that used the 1038 starting in 1970, most used 932s through at least 1971 (maybe others began using 1000s later, not covered in the 'AMAL Reference Catalogue'). Other than the Thruxton and TS350 Bultaco, the only other users of the 1000-Series that I spotted in the 'Catalogue' were AJS that used the 1034 during 1970-73, Boudet (French) the 1036 during 1973-74, CCM the 1034 and 1036 in 1974, Greeves the 1034 during 1972-74, and Maico the 1036 during 1971-74. It appears the Mark 2 came on the scene around 1975 in sizes up to 40 mm so I suppose it was about then that the 1000-Series went out of production.




Attached Files Innovate_probe.jpgDBDexhaust.jpg
Last edited by Magnetoman; 03/26/19 4:41 am. Reason: Thruxton Addendum alteration:
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769339 03/26/19 11:33 pm
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I have investigated further , now the slide is marked 3 1/2 which equates to .21875" but I measured the cutaway at.172" at the outer circumference, which i believe to be somewhere between a 2 1/2 and 3 cutaway. The idea i was toying with was to machine some off the bottom af the slide to effectively reduce the cutaway (and maybe lift the needle to compensate)
This is based on my belief that the cutaway number is equal to 1/16" is this correct? Could someone measure another cutaway and report for comparison ?


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Re: Correct needle for 1000-series Concentrics? [Re: geordie] #769340 03/26/19 11:54 pm
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Originally Posted by geordie
Could someone measure another cutaway and report for comparison ?
The slide in the photograph is marked '2½' and as can be seen the cutaway is two and a half 16ths. Sit it on a flat surface and view the ruler straight on at the height of the cutaway because otherwise parallax will cause a significant error in your measurement.

Attached Files Concentric13.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769348 03/27/19 2:18 am
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Magneto Man

I use the same unit that connects with my dyno unit, and tapped the end for a 1/8 pipe fitting, and install a length of copper pipe to
get further up the pipe. I also made an old pipe my "dyno Pipe" with a o2 bung just below the bracket. It works best!!


Last edited by JakeH; 03/27/19 2:19 am.
Re: Correct needle for 1000-series Concentrics? [Re: JakeH] #769358 03/27/19 3:33 am
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Originally Posted by JakeH
install a length of copper pipe to get further up the pipe. I also made an old pipe my "dyno Pipe" with a o2 bung just below the bracket. It works best!!
The reason the bung in the exhaust pipe works best is the exhaust gas flows by it. A length of Cu pipe relies on diffusion to get the gas from the end all the way to the sensor and that doesn't work very well at all. My probe, modified from the one Innovate sells, has an "inlet" and an "outlet" pipe that sit at different points in the exhaust stream so there's a pressure difference that forces a flow of exhaust gas over the sensor. I added a spacer on the inlet tube to make sure it can't sit flush against the exhaust pipe where the flow is stagnant.

Attached Files Innovate_probe2.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769360 03/27/19 3:57 am
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MM: Interested to recall that some Thruxtons were dispatched with a 930 - as mentioned in the table in Rod Burris' book (noting that the 930 specification quoted is the same as the same as the Venom from the year prior..odd that both bikes required EXACTLY the same jetting, despite different cams, heads, pipes..not sure I trust that data..never minding the fact that Veloce would choke (pardon the pun) at using such a small carb on the VMT, especially when at least the 932 would have been available.)..as a former Thruxton owner (1966, #409) I have the usual literature, though nothing would surprise me at this distance from when they were made. (Mine came to me with the usual 5GP2 and left with a 36mm VM Mikuni. The GP worked fine...the Mikuni transformed it!).

The interesting part came when I transplanted identical 36mm Mikunis onto the Thruxton and (UK) Clubmans DBD, at the same time...the Thruxton was very simple to get the jetting very close, though the BSA took 3x the effort and ran very different jetting...the different jetting was what surprised me. Both were 'standard' (by accepted parts book references!) in terms of cams and pipes.

With respect to air jets, tread carefully. Changes in this regard should not be made to effect changes in any specific area of jetting - the effect of the air jet is to alter the whole slope of the fuel curve. The same overall results can be obtained with different air jets via correspondingly different jetting.

Last edited by Kerry W; 03/27/19 3:58 am.

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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769361 03/27/19 5:12 am
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Originally Posted by Kerry W
With respect to air jets, tread carefully.
Indeed, caution is wise. At the moment I'm torn between an OCD desire to understand the 2-stroke to 4-stroke conversion at a deep level, and just getting it working reasonably well.

Presently I have the carburetor set up with specifications given elsewhere in this thread so it should at least work. I hope. It would have been easy enough to swap the spray tube but I decided to leave it as-is on the first round of jetting. The bung for the air/fuel gauge is due on Thursday so by Friday I should have it installed in the exhaust system I "discovered," and everything in place on the Competition.

I haven't heard anything from DocZ so I can only hope the rear roller shows up soon. Even absent it I'll try it again with the new abrasive on the rear roller so, as I said before, I hope to have the jetting worked out by sundown on Sunday (unfortunately, that's the same hope I wrote a month ago...). Re-reading this post, I used the word "hope" more times than I would have liked.


Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769366 03/27/19 8:17 am
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I'm in commercial aviation...I try to avoid using 'hope' at all times!


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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769434 03/28/19 1:19 am
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Originally Posted by Kerry W
I'm in commercial aviation...I try to avoid using 'hope' at all times!
I'm on commercial planes quite a bit so my hope is the pilots always rely on skill rather than hope. I also hope I don't find myself on a 737 Max 8... Going off on a tangent, I'm reminded that some years ago an out-of-town technician repaired my electron microscope. As he was ready to leave that afternoon he opened his briefcase to check the flight time and I saw the only two other things in there were a radar detector and a bible. Returning to airplanes, I'd much prefer to have pilots who go over the checklist a second time rather than spend that time praying they don't screw up and crash the airplane.

Instructions for locating the oxygen sensor are that it should be at least 24" from the exhaust port to be sure it does not exceed 900 °F/ 500 °C At that temperature steel is just starting to have a faint glow, which I've never seen even near the head since the Gold Star's pipe hangs in the breeze instead of being insulated under the hood of a car at the end of a header fed by four cylinders. The (heated) sensor also should be as near as possible to the top of the pipe so water condensation doesn't hit it when the engine starts up and kill the sensor due to thermal shock.

Anyway, I sawed the megaphone off at the weld to leave the pipe as long as possible and swapped it for the Competition's pipe and silencer for measurement purposes. The location I chose (which also satisfies the instructions for it to be after the Gold Star's turbocharger but before its catalytic converter), is shown by the red 'x' at the intersection of the two pieces of blue tape in the first photograph. This will place it in a protected spot ~21" from the exhaust port.

For aesthetic reasons only it would be nice if the sensor were vertical so as the second photograph shows I used the smallest protractor I have to determine the approximate slope of the pipe there to be ~22-deg. The pipe is curved so this isn't an exact measurement, but by milling the base of the bung at this angle it will be pretty close. Locating the bung with respect to the horizontal portion of the end of the pipe should get me even closer, but that remains to be seen.

As the third photograph shows the bung arrived late this afternoon, a day early. So, with luck, it will be welded in place to hold the sensor perfectly vertical tomorrow.

Cautions are to be found that the lifetime of these wide-band O2 sensors is degraded by the use of leaded fuel, gasoline additives, excess oil in the exhaust, and oil with high Zn content. Luckily, none of those are issues with old British motorcycles...

On another note, the Stellite-tipped pushrods I made for my 1928 Ariel survived the ~3000 miles of the Cannonball with flying colors, and I also used Stellite to repair the lifter that had worn a hole in it. Although I have 1 lb. of 3/32" TIG rods, the smallest size that is "mass produced," it's too large for detailed work. Some of you might remember that at the time a company generously gave me 5 rods of 1/16", which is what I used on the Ariel. Anyway, because I hate not having something as useful as this available if/when I need it I've been looking for a source of inexpensive 0.045" TIG filler since October. Despite extraordinary -- for me -- patience, nothing turned up over the past six months so I bought 1 lb. of 0.045" at full retail, which is ~3x more per pound than it goes for in larger sizes. The general principle with TIG is a too-small rod always can be used, whereas a too-large one is a problem, so this Stellite should serve my purposes well into the 22nd Century.

Attached Files AirFuel01.jpgAirFuel02.jpgAirFuel03.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769439 03/28/19 2:39 am
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MM
Which grade of Stellite do you use?

Re: Correct needle for 1000-series Concentrics? [Re: 998John] #769444 03/28/19 3:30 am
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Originally Posted by 998John
Which grade of Stellite do you use?
Stellite 6. Known generically as ErCoCr-A and sold by various companies under names like Polystel 6, Stoodite 6, Bishilite 6, etc.

Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769524 03/29/19 3:40 am
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I didn't have time to get the pipe completely modified today, but I made a lot of progress. I center punched the pipe while it was in place so I would know exactly where to drill. Slicing the bung at 22-deg. would have removed more of the threads than I would have liked, and I didn't want to order an extended bung and wait until next week for it to arrive, so instead I fabricated a short spacer from a piece of 1"-OD heavy-wall stainless tubing. I sliced it at 22-deg. on the mill then rounded the base using a 1½" end mill, finishing the match to the 1¾"-OD pipe with a die grinder. As can be seen the top of the spacer isn't quite level with the rear portion of the pipe, but I had a plan to deal with that.

After welding the spacer to the tube I put the pipe in the mill, holding the rear portion with the vise and making sure it was properly vertical by means of a 'L' fixture and a bracket bolted between it and the mounting bracket of the pipe. I then milled the top of the spacer flat and parallel to the rear of the pipe.

That's as much time as I had today. Tomorrow I'll weld the bung on the spacer and, if nothing goes wrong, will be done with the modification. I'll remove the 'twitter' silencer from the bike's actual pipe and bolt it in place on this modified pipe. I'll plug the bung until I get the jetting reasonably close and then install the wideband sensor and go hightech on the mixture.

I realized I haven't used the Innovate with my current computer. But, hey, it's only software so there couldn't possibly be any issues...

Attached Files AirFuel04.jpgAirFuel05.jpgAirFuel06.jpgAirFuel07.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769585 03/29/19 10:34 pm
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Originally Posted by Magnetoman
I realized I haven't used the Innovate with my current computer. But, hey, it's only software so there couldn't possibly be any issues...
Who could have possibly predicted there would be computer issues? A half-hour of effort didn't solve the problem, but I have hopes that a new cable due this afternoon will. The LM-1 (and my Superflow flow bench) was made back in the days of RS-232 serial ports, whereas any computer made in more than a decade has USB serial ports. The problem arises because the standards of these two differ in ways that require adapters that contain electronics, and even then a given adapter may work to connect some devices to some computers, but not necessarily the same devices to different computers. Further complicating things have been the ever-moving USB goalposts (1.0, 2.0, 3.0, 3.1, 3.2, ... ) which is one reason why cables that worked on past computers might not work on present ones.

Anyway, a Sewell cable was unrecognized by my computer (a Thinkpad). Although a Belkin cable that worked with my previous Thinkpad and the Superflow was recognized by my current computer as being a Belkin cable, and it got the LM-1 to display "serial interface" as if it were properly connected, still the LM-1 wouldn't communicate (note to self: test whether current computer connects to Superflow). I found on the web that someone managed to connect their LM-2 using a Tera Grand Premium cable so I ordered one, due later this afternoon. Again, the fact that cable worked with a different device (LM-2 vs. my LM-1) and (likely) different computer doesn't necessarily mean it will work for me so this is a $12.50 gamble.

Meanwhile, I finished welding the bung to the pipe. Because the sensor is a little way around the bend it can't be seen through the end of the pipe, but the borescope shows it is nicely positioned to inhale the exhaust fumes that will be streaming by. And, the extra effort resulted in the sensor being vertical, as shown in the third photograph.

Attached Files AirFuel08.jpgAirFuel09.jpgAirFuel10.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769594 03/29/19 11:58 pm
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geordie Offline
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Nice work with the sensor , i positioned mine at the front of the silencer so its a bit further back at the rear of the gearbox, I have only used it briefly but I think it works OK. I didn't have a spare header or I would have done the same.
Does anyone know what sizes the small ports are that are in the bottom of the 1038 body either side of the slide ? I'm wondering if the secondary port may be undersize or partially blocked on mine.


58 goldstar
74 commando
70 Thunderbolt
81 Darmah
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769601 03/30/19 1:19 am
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Nothing but frustration so far with getting data from the LM-1 to the computer. After a half-dozen downloads, driver updates, removing and reinstalling programs, and reboots I can get the computer to display real-time data from the LM-1, but if I try to download a recorded file from the LM-1 to analyze the program that Innovate supplies for this (Logworks) just disappears a few sec. after I click on 'connect'.

All is not lost while waiting for a hoped-for fix from Innovate's support staff since I can read the air/fuel ratios from the LM-1's display and memorize those figures at various throttle positions (as I ride down the road trying not to be distracted too much...). Being able to calmly look at a plot that also has rpm and throttle position displayed certainly would reveal more than doing it that way, but it will be much better than nothing.

Originally Posted by geordie
i positioned mine at the front of the silencer
The header I'm using must have been shortened before the megaphone was welded on. I have a rusty silencer with a long 1¾" exit pipe that I can cannibalize to extend the header but I don't want it to be either too long or too short so I need to make some measurements from the three Goldlocks... er, Gold Stars to get it just right. I would like it of a length such that silencers properly bolted on the frame and mated with the pipe don't have any issues with air leaking in. Too long isn't necessarily better than too short because the pipe could interfere with baffles. Anyway, it's one more thing to do.

Originally Posted by geordie
Does anyone know what sizes the small ports are that are in the bottom of the 1038 body either side of the slide ? I'm wondering if the secondary port may be undersize or partially blocked on mine.
If you're referring to the two tiny passages adjacent to the slide on the engine side of the carburetor, I haven't measured those but easily can if that's what you need. If you're referring to the compensating air passage down the centerline to the jets, in all three series (600, 900, and 1000) of 4-stroke Mark 1 Concentrics it's ~0.189"-dia.. However, in a 627 from a Bultaco Sherpa-T the air passage necks down to ~0.098"-dia. just before reaching the jets. The same ~0.098" constriction is in the much larger 2-stroke 1036 and 1038.

Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769647 03/30/19 7:56 pm
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koncretekid Offline
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"waiting for a hoped-for fix from Innovate's support staff"

Good luck with that. I have the Innovate MTX-L wide band air fuel ratio gauge along with 3 other of their gauges including manifold pressure/ shift light which gives me rpm and exhaust gas temperature. Like you, it's nice to have the ability to see A/F in real time, but not much use unless you know other info at the same time. So I opted for their Pocket Logger with SD card so all gauges and the logger are daisy chained together. All I have ever been able to log is about 8 seconds of any run after which it quits logging. Calling their support staff for advice, the only answer I ever got is that "our gauges are made for new bikes so it might not work on yours."

The MTX-L also has additional inputs and outputs for power and lights as well as a 0-5v output which I can connect to my Performance Trends dyno software on my homemade chassis dyno and after inputting the calibration data, generates good data along with my torque, hp, exhaust gas temperature, and has several unused inputs for further use. I'm using Windows 10 on a dedicated computer for all my data.

They did tell me that I was probably getting interference from the ignition system, but somehow it works fine with the P.T. software on the dyno.

https://www.innovatemotorsports.com/products/mtxl_plus.php

Tom


Life's uncertain - go fast now!
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769649 03/30/19 9:13 pm
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Originally Posted by koncretekid
all gauges and the logger are daisy chained together. All I have ever been able to log is about 8 seconds of any run after which it quits logging. ... the only answer I ever got is that "our gauges are made for new bikes so it might not work on yours." ... They did tell me that I was probably getting interference from the ignition system,
Based on that, if they ask I'll tell them I'm using my LM-1 on a 2019 Harley to avoid the possible response of it not having been designed for old or foreign motorcycles.

Having a chain of instruments interconnected on a common bus is harder to shield against EM interference than the LM-1's system of a single shielded cable to the oxygen sensor and another to the auxiliary input. At least, knock wood, I not had problems in the past.

Other things came up so today had to be a short day in the garage. Which means I may not make my hoped-for Sunday evening deadline for having the jetting sorted out. I did have enough time to install the pipe and silencer and was pleased to find the pipe only a fraction of an inch shorter than it was when new. Hence, I won't have to cut, weld, and grind an extension, saving quite a bit of time. As the first photograph shows I have the sensor bung blocked off for the moment, and will switch to the air/fuel meter once it "feels" like I have the jetting close.

The second photograph shows the "jetting kit" I assembled for sorting things when I get it running and head out on the road. There's a 340 main jet in the carburetor now, so the kit has five each larger and smaller jets, baggies to keep them separate to make finding the next one easier, socket to change jets, screwdriver to remove the plug at the bottom of the float bowl, cup to catch the fuel to pour back in the tank rather than soak into the ground, screwdriver for the idle and pilot mixture screws, spanner to remove the carburetor, and Philips screwdriver for the top so I can change the needle clip. As long as the cutaway turns out to be OK this kit should get the jetting as close to correct as is possible on suburban roads and by feel alone.

Attached Files AirFuel11.jpgAirFuel12.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #769656 03/30/19 10:51 pm
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kevin roberts Offline
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i'll be very interested to see what numbers you get for AF.

i occasionally run an AEM AF unit and get the best performance at numbers other than what people predict.


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