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Correct needle for 1000-series Concentrics? #768040
03/13/19 9:52 pm
03/13/19 9:52 pm
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Magnetoman Online content OP

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Question: Do 1000-series AMAL Concentrics use the same needles as 900-series?

Making a long story long, I had all sorts of carburetor problems when I got my Catalina until I finally discovered, almost by accident, that its large 'D' Monobloc had a too-short 'C' needle from a smaller carburetor. Replacing it with the correct needle made all the difference.

My Competition now sits with its transformation 99.9% completed from a "Clubman" with clip-ons and 6-gal. Lyta tank to more of a modern cafe racer with low handlebars, 2-gal. alloy tank, and rear sets. However, even though I know enough to leave well enough alone, I've decided to significantly alter the Concentric carburetor that's on it. This only can be described as a self-inflicted wound.

When I got the bike 24 years ago I did quite a bit of work on it before it was ready to ride. At some point during that process I removed the GP and replaced it with a 36 mm 1036 Concentric and also around that time turned it over to the now-deceased guy who owned the BB and Catalina I now have to sort out some issues. He got the carburetor working well, which is what I should leave alone. But...

The carburetor is in 2-stroke configuration. As the first photograph shows, a 4-stroke jet holder (bottom) is longer because it is said that otherwise the main jet would interfere with the longer 4-stroke needle. Not as obvious, the needle jets also are different as suggested by the hole in the four-stroke version. In addition, as the second photograph shows, the spray tube in the bottom of the bore is slash-cut in the 2-stroke version at the left but flat on top in the 4-stroke at the right. This can be changed by pushing the old one out and the new one in, and the jet holder and needle jets are easy to switch as well.

This brings us to my question about the needle. The "Carburetor" tab in my two-volume bespoke Gold Star shop manual is 3/4"-thick (~190 pages), containing everything useful I've run across for GPs, TTs, Monoblocs and Concentrics. Unfortunately, there is relatively little about the 1000-series Concentric, and nowhere can I find if they use the same needles as the 900-series. It's a bigger carburetor so it wouldn't surprise me if the needles were different, but maybe they were the same(?). Having been burned once by a too-short needle, I'm proceeding cautiously.

Correction: As the third photograph shows the needle I took from a 4-stroke 932 is a tiny bit longer than the needle that was in a 1038 Concentric (2.678" vs. 2.644") I have on the shelf. However, the needle that was in my 1036 is only 2.297" long (i.e. ~0.38" shorter than either in this photograph) with 1 groove in it, which a table tells me is a "rich" 2-stroke needle for a 900 series. For what it's worth, the needle from the 932 has 2 rings on it so it is a "standard" 4-stroke needle, while the one from the 1038 has the letter (or number) 'O' stamped at the top which the AMAL site tells me is a 1000-series 2-stroke needle.

So, is the 0.034"-longer needle from the 932 appropriate to use in my 1036? If not, what is the part number of the needle I should use?

p.s. In case it helps someone in the future, the present jetting that works in my 1036 2-stroke Concentric on a DBD with 65-2446 inlet and exhaust cams, 10:1 piston, 'twitter' silencer but no air filter is:

25 pilot
.107 needle
2-stroke rich needle (1 groove, 2.297" long) on middle notch
2-stroke spray tube
#3 cutaway
290 main jet

p.p.s. Before someone tells me I should get a Mikuni, I have two 38 mm Mikunis (and a 1038 AMAL) on the shelf. So, you don't need to tell me to get a Mikuni (you could tell me I'm a fool for not using one, but you needn't bother telling me to get one...).

Addendum:

I used a piece of 5/16" Al rod to make the tool shown in the fourth photograph to press the spray tube out of a donor 900-series Concentric. The end that fits into the tube is 0.243"-dia. and the section that fits through the carburetor as it pushes the tube out is 0.309"-dia. The smooth portion of the tube is a slip fit in the body with the knurled end the portion that secures it in place.

I'm a little puzzled because I measured the knurled end to be 0.372" which means the hole into which it was pressed must have started life a few thou. smaller than 3/8". Typically, holes are made with tooling that has the nominal diameter while the shafts that go into them are appropriately under or over-sized.

Anyway, the knurls in the carburetor can be seen from the fifth photograph. The top of the jet holder doesn't reach nearly as far as the bottom of the spray tube so I'll have to count on the same knurls in the 1036, plus Loctite for good luck, holding the replacement spray tube in place.


Attached Files Concentric01.jpgConcentric02.jpgConcentric03.jpgConcentric04.jpgConcentric05.jpg
Last edited by Magnetoman; 03/14/19 3:05 pm. Reason: addendum plus correction
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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768053
03/14/19 12:07 am
03/14/19 12:07 am
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argyll. scotland, uk
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http://amalcarb.co.uk/mk-i-Concentric-series/1000-series/needles.html


Taken off Amals page for 1000 series spares, the 4 stroke V needle has the same part number as the 900 series, the two stroke needle and alchohol needle have 1034 start numbers and are not listed in the 900 series parts.
Guessing here, but possibly the needle seat in the slide is the same height as the 900 series, Ive never seen a 1000 carb, and the other two one off needles are special tapers?
In the UK Surrey cycles know more about AMAL carbs than pretty much anyone else, try emailing or calling them, they are very helpful over the phone.


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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768060
03/14/19 1:26 am
03/14/19 1:26 am
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Magnetoman Online content OP

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Originally Posted by gavin eisler
Guessing here, but possibly the needle seat in the slide is the same height as the 900 series,
Good call. Your post sent me back to the garage to check, and indeed they are the same height, as is shown in the first two photographs (it's not easy to tell from the second photograph, but the top of the seat in both is the same height above the base of the slide).

However, as the third photograph shows, the projection for the jet holder on the 1036 (on the right) is ~0.050" shorter than on the 932.[*] This physically raises the needle jet by that amount which has the same effect as dropping the needle by almost 1 notch (0.063"). Perhaps this is all within the overall scheme of things due to differences in air flow when chokes get massive.

Given that the AMAL site shows different 2-stroke needles, but the same 4-stroke needle, as for the 900 series, I was worried that might be a mistake on their site. Thanks to your suggestion, I'm now less worried. However, I'd still like to hear from people whose 4-strokerized 1036 (or 1038) works well and who knows for sure what needle is in it.

[*]A more careful measurement found ~0.035", which is equivalent to only ~1/2 notch of the needle. I also checked a 600-series and found it to be identical to the 900.

p.s. In light of this latest revelation I see now that the same 4-stroke needle is used in 600, 900 and 1000-series Concentrics, although the 2-stroke needles differ for each. I had not realized this before. Although I have a Concentric on my BB Gold Star, because that's how it came to me, I grew up in a pre-Concentric world. Oh, also on my Trident, but that's an anomaly in my world.

Attached Files Concentric06.jpgConcentric07.jpgConcentric08.jpg
Last edited by Magnetoman; 03/14/19 2:09 am. Reason: [*]
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768073
03/14/19 5:24 am
03/14/19 5:24 am
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Interesting, and asks questions I've long held too, regarding the 2 to 4 stroke changes required. I'd done all the research years ago, but never actually got to changing the spray tube, etc.

Unfortunately, my bike that had a 1038 on it, as a road-racer, is long gone, but I might be able to get the current owner to provide some data. It might take some time though..he doesn't visit his computer much!

One thing I am confident about - the spray tube won't escape down the inlet if it does come loose..


No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768090
03/14/19 11:54 am
03/14/19 11:54 am
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MM,

My DB is similar to your specs, but 9-1 instead of 10-1 and I run an air cleaner.

I am not going to go off memory, but let me see what I have written down for the jetting with a 1038 converted to a 4 stroke carb. I am still a little off with the slide cutaway (rich) but that has not been enough of an irritant to make it better.

I tried a 1036 that was converted to 4 stroke but the bike just never seemed to run right. A 1038 made all the difference in the world.


Never underestimate the human ability to elevate stupid to a whole new level!.
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768127
03/14/19 7:39 pm
03/14/19 7:39 pm
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Magnetoman Online content OP

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Originally Posted by Rich B
I tried a 1036 that was converted to 4 stroke but the bike just never seemed to run right. A 1038 made all the difference in the world.
Although there aren't many 1036/1038 Gold Star specs to be found, those on Britbike span a pretty wide range:

pilot jet 25, 30 or 35
slide 3, 3.5 or 4
needle jet .108
main jet 300 - 390

Unfortunately, it isn't always clear whether some of these results are based on personal experience, or just repeating results posted by others. So, I feel I'm in largely uncharted seas, like those of the first photograph.

In addition to the above jets, the configuration of spray tubes required to make engines happy also ranges widely, as shown along with the direction of air flow in the second photograph. Note that the angle of the slash cut in the Trident/Rocket3's spray tube is steeper than that of a 2-stroke, although it only covers half the diameter, while the cut in the Norton's is even more radical. For the Trident/Rocket3 a relatively small 27 mm carburetor feeds a 247 cc cylinder, while for the Norton a larger 32 mm carburetor feeds a 414 cc cylinder so the effect of spray tube geometry covers a wide range of cylinder and carburetor sizes. The only thing I've found is one unconfirmed report that a non-notched spray tube in a Norton causes a mid-range flat spot. Typically "flat spot" would mean a lean mixture, but it could be rich depending on who is (mis)diagnosing the condition.

Anyway, with the above in mind, plus the aggressive cam overlap of a Gold Star that causes fuel to pass across the spray tube more than once, and given my present state of ignorance[*], it's not at all obvious to me that a 2-stroke spray tube for my engine would be "bad" while a generic flat-top 4-stroke would be "good."

[*]Joseph Heller nicely sums up my knowledge of spray tubes with this quote from Catch 22: "Come to us with a liver complaint and you can fool us for weeks. The liver, you see, is a large ugly mystery to us. If you've ever eaten liver you know what I mean. We're pretty sure today that the liver exists, and we have a fairly good idea of what it does whenever it's doing what it's supposed to be doing. Beyond that we're really in the dark"

The inlet port of my DBD head measures 36.80 mm (1.449"). In addition there's a phenolic spacer that's slightly larger at 37.2 mm. Since I have both a 1036 (whose outlet measures 36.0 mm) and a 1038 (38.0 mm) I tried them on for size. One thing to note is the holes in the flanges are slightly larger than the OD of the studs so there's a measured up/down free play of 0.010". That said, normally someone would tighten the nuts while the carburetor hung in the low position rather than try to center it on the studs so it would sit ~0.005" lower than the centerline of the studs.

The third photograph shows the step when the 1038 bolted directly to the head, without the phenolic spacer. Such steps can be caused by undersized gaskets and often cause problems with idle and low speed running because the fuel from the pilot circuit hugs the bottom of the tract for quiet a distance.

I'm not bothering to include a photograph of the 1036 without the spacer because the ~0.4 mm step down from the carburetor to the larger inlet can't easily be seen in an iPhone photograph with poor lighting. However, the fourth photograph shows the 1036 with the slightly larger diameter phenolic spacer in place, where the tract goes from 36 mm to 37.2 mm and back to 36.8 mm. For the 1038 this would be 38>37.2>36.8, which might seem to be better because it is a "smooth" progression, but air flow doesn't live by such simple arithmetic so there's no way of knowing without actually testing it.

Just for interest, the fifth photograph shows the 1038 sitting on the 1036 with the 1036's flange blued to make it more visible.

The Plan: What I'm thinking as of now, subject to changing my mind, is to change the jet holder and needle of the 1036 to 4-stroke versions but leave the 2-stroke spray tube in place. Then, I'll see if I can sort out the jetting to give good performance throughout the range. If I can't, I'll replace the spray tube and see what difference it makes. Assuming I eventually succeed in getting the 1036 working well, I'll then apply the identical configuration to the 1038, swap carburetor bodies, and make whatever tweaks are needed to it to optimize its performance. Because of the Catalina's air cleaner and Monobloc screw top it's quite an ordeal to swap carburetors on it, but it's much easier with the Concentric on the Competition. Unless some unforeseen obligation arises, optimistically I hope to have the jetting sorted out by sundown on Sunday. Whatever I find with my 1036/1038 experiments should be of interest to more than just me.


Attached Files PirateCoast.jpgConcentric09.jpgConcentric10.jpgConcentric11.jpgConcentric12.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768134
03/14/19 10:24 pm
03/14/19 10:24 pm
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Originally Posted by Magnetoman
The Plan: What I'm thinking as of now, subject to changing my mind, is to change the jet holder and needle of the 1036 to 4-stroke versions but leave the 2-stroke spray tube in place. Then, I'll see if I can sort out the jetting to give good performance throughout the range. If I can't, I'll replace the spray tube and see what difference it makes. Assuming I eventually succeed in getting the 1036 working well, I'll then apply the identical configuration to the 1038, swap carburetor bodies, and make whatever tweaks are needed to it to optimize its performance. Because of the Catalina's air cleaner and Monobloc screw top it's quite an ordeal to swap carburetors on it, but it's much easier with the Concentric on the Competition. Unless some unforeseen obligation arises, optimistically I hope to have the jetting sorted out by sundown on Sunday. Whatever I find with my 1036/1038 experiments should be of interest to more than just me.

I think you need to replace the needle jet as well. The bleed hole makes a difference

Re: Correct needle for 1000-series Concentrics? [Re: Shane in Oz] #768135
03/14/19 10:50 pm
03/14/19 10:50 pm
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Originally Posted by Shane in Oz
I think you need to replace the needle jet as well. The bleed hole makes a difference
Right you are. I showed the holy jet in an earlier post.

Update: my hoped-for Sunday completion date may have slipped through my fingers. I have ~20 4-stroke Concentric needle jets from .105 to .113, but I just found that none of them are the .108 that some people have said is needed (a .106 that I previously misread made me think I had a .108). I've now ordered two of them but based on the fact most bikes take a .106, including the B50MX, I'm a bit skeptical something as large as a .108 is needed. While waiting for the .108s to arrive I'll try a .107.

Last edited by Magnetoman; 03/14/19 11:47 pm. Reason: update:
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768148
03/14/19 11:53 pm
03/14/19 11:53 pm
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It is a miracle, I remembered to look in my notebook.

And there is a break in the AFT race from Daytona.....so here it goes

Pilot jet - 30
Slide - 3
Needle - 4 stroke 2 rings, top groove
Needle jet - 107 4 stroke
Main jet - 340
Spray bar - STD. 4 stroke.
K&N air filter

IMO I am a bit rich on the slide, but the mid range/top end gives a great plug reading. The bike starts easy, takes throttle well, so having a hard time convincing myself to make it better. Mid range is amazing.

I live about 900’ elevation, typical east central Ohio weather.


Never underestimate the human ability to elevate stupid to a whole new level!.
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768150
03/15/19 12:04 am
03/15/19 12:04 am
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"optimistically I hope to have the jetting sorted out by sundown on Sunday." Good one MM, I note you didnt say which Sunday, stay optimistic. At least its half the work of a twin, but you have a few variables to deal with.
I recall helping a friend out with twin 32 Miks off a 500 twin Suzuki 2T fitted to a hotted up A10, these were the hot ticket, even with the slides in backwards " You cant get them wrong , they are polarised" says he, " Aye ye can" I said, and he did. Even then the bike ran , obviously wrong , but it ran, did 4 mpg. Improved a lot with the slides fitted correctly enough improvement to run well enough , its all relative.He spent some more time fiddling with the main jet and that was it, then the crank broke. My point is . probably most folk fitting new/ big/ different carbs pay scant heed to the finer points, so long as it runs, might have a flat spot, might need constant blipping but it runs, I doubt if many have the time / skills or inclination to get much further than that, too much uncharted territory and miss understanding. Best of luck with your trials, only guessing here , but going from 2st to 4 T spray tube, I imagine you may need a richer slide or different richer needle position to compensate, this is pure conjecture , probably wrong, . Do the reverse . As I understand it the cutaway has an en richening effect, removing it should need some other type of compensation, its probably too rich as is, you might not need to , who knows?

Moving the needle jet up a wee bit in the 1000 probably keeps it proportionally in the same position as the 900 as a ratio from centre to jet compared with choke OD. If it was me I would fit the 38 and copy Rich Bs settings when he posts them, just to have a known baseline. have you got Lambda sensor gear to help you out? I am very jealous of that stuff, my seat of the pants, choke lever tests are just one step above guesswork, numbers would be cool. I dont know if this is a fair comparison, but my 732 has two 30 mm carbs same as the 650 same cams same pipes, bigger valves, compared with 650 carb setting I am lower numbers MJ, NJ and needle. Extrapolating wildly from this one sample , fitting a 36 in place of a 38 to a 500 will give similar effects, higher gas speeds in the smaller carb mean smaller jets etc compared to a lower gas speed/ bigger carb. Taking a stab at it with some schoolboy maths , 36 mm choke area 1018.mm Sq, 38 mm choke area 1134, percentage difference 116 /1134 x 100/1 = 10% of 38 . This reduction factor could be applied to rich bs settings as a crude start point for the 36. Again, almost guess work , but its a start point.

Last edited by gavin eisler; 03/22/19 10:51 pm.

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Re: Correct needle for 1000-series Concentrics? [Re: Rich B] #768151
03/15/19 12:06 am
03/15/19 12:06 am
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Magnetoman Online content OP

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Originally Posted by Rich B
I remembered to look in my notebook.
Being a life-long keeper of notebooks, often my problem is remembering which notebook to look in.

This is great information. Thanks very much. Since my engine now has a K&N filter on it I'll start out with your settings, except for keeping the 2-stroke spray tube for now. I wonder if the richness you have will result in me ending up with a .106 needle jet. We'll see.

Again, thanks very much.

Originally Posted by gavin eisler
have you got Lambda sensor stuff to help you out?
Indeed I do. However, it helps a lot to get close before deploying advanced technology. When the Catalina returned from our Texas ride 18 months ago it ran OK-ish, but the tale of how I found the needle jet had worn out, the fuel level was 1/2" too low, and the replacement silencer was sending a very rich cloud back through the carburetor to screw jetting up only when the air filter was attached can be found here. Only after locating and sorting out issues like that is it time to capture a stream of data to five significant figures.

Originally Posted by Rich B
Just to be clear, the bit rich spot is very low throttle settings when the slide is primary control.
That's very helpful. I pay particular attention to whether I need to machine a larger cutaway in the slide.

Last edited by Magnetoman; 03/15/19 12:32 am.
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768153
03/15/19 12:29 am
03/15/19 12:29 am
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YW

Just to be clear, the bit rich spot is very low throttle settings when the slide is primary control. Once on the needle/needle jet, I am very happy with the plug reading and response.


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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768164
03/15/19 6:03 am
03/15/19 6:03 am
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Standing by with interest in the results.

MM, can you use your uber-accurate measuring kit to find a worn .107 in lieu of a fresh .108?


No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768172
03/15/19 12:06 pm
03/15/19 12:06 pm
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As a reference on Concentric needles, I give you this. It is not an original, I plagiarized this from a John Healy post something like 11 years ago. So thanks John!

AMAL Concentric Needles

AMAL supplied 5 needles for that MKI Concentric. they are identified by thin annular grooves above the three needle clip grooves.

1 ring is rich two stroke approx. 2.290" long
3 rings is lean two stroke approx. 2.485" long
2 rings is standard 4 stroke approx. 2.677" long
4 rings is Norton 850 approx 2.765" long
5 rings is T160 approx 2.735" long

This is from my own info....

Spanish made 2 stroke needles may also have a letter stamped on the needle indicating rich or lean 2 stroke. Since it is in my notes that are not handy, X & U runs in my mind as the letter. If I am wrong, I will correct that.


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Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768181
03/15/19 4:50 pm
03/15/19 4:50 pm
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Magnetoman Online content OP

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Originally Posted by Kerry W
can you use your uber-accurate measuring kit to find a worn .107 in lieu of a fresh .108?
I have my doubts whether a .108 is going to be needed, supported by Rich B's jetting data where he has a .107. But, as soon as I discovered my "108" actually is a .106 I measured all the .107s hoping to find a large one, just in case. All were within spec. However, although I don't think I'll need them, I still ordered a pair of .108 to have on hand.

Originally Posted by Rich B
As a reference on Concentric needles, ...
I have a printout of John's tuning information with part numbers for various needles in the form of a ~20-page document titled "Beyond the Basics." It is chock full of very useful information but doesn't touch on the 1000-series Amals, probably since none were used on British motorcycles, only on Spanish 2-strokes.

AMAL's current web site shows the same 2-groove, 622/124 standard 4-stroke needle was used for 600, 900 and 1000-series bodies, but different 2-stroke needles for each. They still list a 4-groove for Norton (with a 928/104 part number consistent with having been introduced with the 900-series carburetor used on a Norton 850), but the 5-groove is listed as "4-stroke emission" (622/278, consistent with the 600-series used on a Trident). The 2-stroke needle for the 1000-series is termed needle 'O" (1034/063), which is what is stamped on the needle I removed from one of my carburetors.

Having learned from replies in this thread that the same standard 4-stroke needle is listed for all three series, plus having the dimensions in John's booklet, gives the possibility of an additional level of fine tuning. For example, the 5-ring "T-160" needle is 0.058" longer than the standard, with a gentler taper that begins 0.024" sooner. So, if otherwise everything else is good, but the mixture gets too rich too fast as the needle is withdrawn, switching to a T-160 needle could address that. Referring to Gavin's earlier post, it's after the basic jetting has been figured out that my digital air/fuel system will come into its own to tweak the jetting into being as good as it possibly can be. Until the carburetor starts to wear...

Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768223
03/15/19 11:14 pm
03/15/19 11:14 pm
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Stone Creek OH USA
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Rich B Online happy

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Good thing I didn’t go off memory for Spanish 2 stroke needle....

U - std 900 series 2 stroke 57.93mm/2.28” long
X - rich 900 series 2 stroke (the only one I have is in a carb on a bike)
X-1 richer 900 series 2 stroke (I don,t have one)
O - std. 1000 series 2 stroke 66.86mm/2.63” long
O-A - rich 1000 series 2 stroke (none to measure)

Good thing this subject came up......forced me to look at Spanish AMAL info. I need to find some 1000 needles.....building 2 Bultaco vintage flat track bikes is gonna require spares.


Never underestimate the human ability to elevate stupid to a whole new level!.
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768238
03/16/19 4:00 am
03/16/19 4:00 am
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Middle East,
Kerry W Offline
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MM...contrary to the above, 1000 series (1036) Amals were used on very late Velo Thruxtons. (incidentally, with a 30 pilot, .106 nozzle, 320 main and a 3 slide - no mention of the needle variant - assumes standard - with clip in the top groove, and the use of the '1034/70 air tube'. In another veto book there is mention of a 1036 on a Thruxton, with a 'slash cut' spray tube, 30/320/.106 setup, though with a 2.5 slide and the needle clip in the 2nd groove and 70mm intake trumpet).

Also, as a minor aside, one reference to stock 1036's on the Velo notes the use of the 622/056 'alcohol' float bowl, with the 4mm/0.156 feed hole.


No generalisation is wholly true, not even this one.
Oliver Wendell Holmes
Re: Correct needle for 1000-series Concentrics? [Re: Kerry W] #768243
03/16/19 5:00 am
03/16/19 5:00 am
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Magnetoman Online content OP

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Originally Posted by Kerry W
(1036) Amals were used on very late Velo Thruxtons. (incidentally, with a 30 pilot, .106 nozzle, 320 main and a 3 slide - ... with clip in the top groove, and the use of the '1034/70 air tube'. In another veto book there is mention of a 1036 on a Thruxton, with a 'slash cut' spray tube, 30/320/.106 setup, though with a 2.5 slide and the needle clip in the 2nd groove and 70mm intake trumpet).
That's all very helpful information. Thanks very much. I'd forgotten that Velocette survived past the Jurassic into the Concentric era.

It was one of those two steps forward, one step back, and repeat, kind of days. But, the Gold Star started on the 3rd kick and I made two laps of the driveway so it wasn't a bad day at all.

I needed to put an Ewarts-type right-angle push/pull petcock on the right side because of limited clearance over the carburetor, but using cork for a seal was a little too 19th Century for my sensibilities. I was planning to machine my own O-ring plunger when last week someone on the Ariel Owners Club forum mentioned that Baxter Cycle carried them. I started to order one plus a spare (at $20 ea.) but the order form showed that shipping was free if I ordered $50 worth of merchandise so I ordered three to save the $8.50. Depending on how you look at it I either got the third one for $11.50, or I paid $60 for the one I'm actually using.

For reasons of expediency one petcock has an outlet tube that's 1/4" OD while the other is 5/16". I machined a brass adapter for a Cu 'T' to give it 1/4" and 5/16" inlets and a 1/4" outlet to connect to the carburetor.

I then rebuilt the 1036 using Rich B's settings for his 1038 (30/340/.107/#3/top groove), except leaving the 2-stroke spray tube in place. After installing it I lowered the lift, wheeled the bike out to the carport, and decided to try to start it the old fashioned way. It started on the 3rd kick and I made two laps of the driveway before stopping to adjust the throttle stop (yes, I know it wasn't warmed up yet). It's a left hand carburetor and while balancing the bike to try to do this it died. It didn't start after a couple of kicks so I put it up on the DocZ rollers. The photograph shows how I modified the rollers with a removable cross bar that I can use to strap the bike in place, which is quite handy at times like this.

The rollers didn't have the h.p. to turn the engine over so that, plus a glowing terminal on a relay, told me one of the two starter relays was fried. When I initially installed the second motor I ran both off the same relay a few times before installing a second one, which I shouldn't have done. Anyway, this setback sent me to the local Autozone for a replacement. I rolled the DocZ back to the garage to put on the lift to install it, then rolled it back to the carport. The rollers worked for about 3 sec. and died abruptly. Thanks to my superior electrical skills I was able to diagnose the problem. The electrical connector at one of the battery clamps had broken in two separating the cable from the battery. So I then fabricated a new connector from a sheet of Cu and crimped it on the cable.

With the DocZ back in action the Gold Star started. But, the sun was about to go down and the temperature had dropped below 70oF into the frigid 60s so that ended the day.

Attached Files Competition01.jpgCompetition04.jpgCompetition05.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768304
03/17/19 12:45 am
03/17/19 12:45 am
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Another day is done, and at the present rate of progress my Competition Gold Star may never run. Sigh...

Today the DocZ just didn't have the h.p. to spin the engine over more than a few revolutions before running out of steam. Since yesterday I had installed a new solenoid I suspected one of the motors wasn't getting power so I connected two clamp-on ammeters to the leads. They showed that both motors were getting power, but that the current in each dropped from ~200 A to ~100 A within ~5 seconds. So, I tested the battery (which was four years old) using a tester that draws ~100 A and it showed up as "weak."

I put the battery in the car and drove off to buy a replacement. There was a $12 core credit, but the guy at the store insisted he had to test my battery to see if it was any good before he could issue the credit against the new battery, and the test would take 15 min. I said my battery was bad, I wasn't returning it under warranty, I just wanted the credit and to be on my way. Since clearly I was an idiot for not understanding, he slowly explained to me that it was store policy. I asked him to call the manager but before they showed up the battery failed the test and I got the credit.

Once back in the carport I hooked up the battery and it spun great. Except the tire wasn't turning. As shown in the first photograph I found one of the rollers had shed its abrasive covering (nb. DocZ now sells rollers with a laser cut pattern in them rather than using abrasive paper). I have abrasive paper in all sorts of grades, but only small amounts of coarse abrasive cloth so off to the Ace Hardware. I found they have 10,000 (estimated) varieties of sandpaper but, after a lot of looking, only one package of abrasive cloth, containing an assortment of three grades.

Back home I found my 1 gal. container of Barge Cement was less than fully liquid. If it's not one thing, it's another. Sigh... The solvents it uses (e.g. toluene) aren't anything I care to use for anything so I had nothing to use as a thinner. Still, it was liquid-y enough to (barely) use so I smeared it on the roller and on the back of 50-grit cloth, waiting the necessary five min., and attached it as shown in the second photograph.

After the cement dried I put the Competition on the DocZ, which then almost instantly shredded the cloth as shown in the third photograph. The glue seemed to be fine, it was the cloth that wasn't up to the task. The bike tends to climb onto the back roller so that one gets most of the wear. Although the abrasive on the front roller is still OK, swapping rollers isn't an option.

I am very interested in suggestions for what abrasive material I can attach to the roller that won't disintegrate so I can get back to jetting the bike.

Attached Files Roller01.jpgRoller02.jpgRoller03.jpg
Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768370
03/17/19 9:18 pm
03/17/19 9:18 pm
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England
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George Kaplan Offline
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Originally Posted by Magnetoman
Since clearly I was an idiot for not understanding, he slowly explained to me that it was store policy.


I am afraid it is a symptom of the modern age. Store assistants seem to be incapable of independent thought and have been told to keep to The Script. because the rest of us are, as you say, idiots.

I went to a large car parts store a while ago and asked for some EP80/90 gear oil (it was for a van). The young guy behind the counter asked me for the vehicle registration number and I repeated I just wanted the said oil. He said that he needed the number so I obliged. After a minute of tapping at his keyboard he informed me that they didn't stock any oil for that vehicle. I told him that I couldn't believe that they didn't stock EP80/9 gear oil and at that point another guy came to the counter from the warehouse behind and heard me asking the last question. The new guy then said that they had loads of it in the warehouse. WTF!

Sorry for going off on a tangent.

Back on topic, what about using some of that stuff that gets used to put anti slip coatings on things like steps? My initial thought is that boats may use something so try a chandlers? Or a building supply place if they use it on metal steps?

Also, what about asking DocZ what they used?

John

Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768392
03/18/19 12:01 am
03/18/19 12:01 am
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Posts: 4,592
argyll. scotland, uk
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Rubber,maybe? dunno about gluing it on, the steel roller isnt helping, neither is the tight radius , the sort of stuff they make sander belts out of is pretty sturdy. Wind it on barbers pole style with a decent contact cement. Thats how drum sanders are made. usually on a bigger ( plywood laminated disc ) drum though.


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Re: Correct needle for 1000-series Concentrics? [Re: gavin eisler] #768405
03/18/19 1:58 am
03/18/19 1:58 am
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Posts: 5,229
U.S.
Magnetoman Online content OP

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Originally Posted by George Kaplan
what about using some of that stuff that gets used to put anti slip coatings on things like steps?
Also, what about asking DocZ what they used?
Originally Posted by gavin eisler
Rubber,maybe... the sort of stuff they make sander belts out of is pretty sturdy. with a decent contact cement.
Anti-slip paint is a good suggestion that sent me to McMaster-Carr. There I came across anti-slip tape that looks like it might be the stuff DocZ used originally. I emailed him yesterday but for now I'll assume he doesn't check email on the weekend but will promptly reply tomorrow...

The not-fully-liquid contact cement I used may well have contributed to yesterday's failure (solvent for it is on order). That, plus not removing all the old material before gluing on the new. This left voids under the new material which easily could have cracked resulting in rapid disintegration. If it wasn't such an effort to disassemble the DocZ then placing the roller in the lathe to remove the old material (and maybe knurl the roller?) would be easy. I'll have to see how difficult it is to scrape clean in situ once I hear back from DocZ. I don't want to do anything until then (because it will be a messy job and I'm waiting to hear from him as an excuse to procrastinate).

The torque of my 10:1 Competition is causing issues with the DocZ that none of my lesser machines have ever experienced. I tried once with my leg today but the backfire reminded me why I got the rollers in the first place, i.e. to save my leg for another day.

The problem with turning over this high compression engine is due to a combination of electrical losses and friction. Addressing electrical first, the new battery I bought yesterday is for marine use so it has screw terminals that I can use to make the best possible low resistance contacts to it. The jumper cables supplied with the DocZ are 4 AWG which a calculator shows have a 6% voltage drop when powering both motors under full load. That the present cables are undersized can be felt in the heat generated in the wires. Anyway, this loss is too much so I ordered 1/0 AWG cables to replace them (which will reduce the drop to 2.4%). When it arrives I'll make my own Cu connectors for both ends of the cables. I also modified the battery clamps I bought previously to replace the DocZ clamps, installing Cu pads to make contact with much greater surface area to give lower resistance. At the same time I made 1/8" x 1" Cu pads (equivalent in cross section to 3/0 wire) that bolt directly to the battery to which the clamps clamp. Even with the present 4 AWG cables this made a noticeable difference in the power delivered to the motors. Yes, a direct hard-wired connection would have the lowest resistance, but no way would I consider doing this on a portable setup. With clamps there's hope to knock one free in an emergency.

The new battery is rated 845 MCA, which means it can supply that much current for 30 sec. at 32 oF before the voltage drops below 7.2 V. However, since the current will drop proportionally, by the time the voltage drops that much the power to the motors will be reduced by (7.2/12)2 = 60%, i.e. to 40%. The power available in a battery goes up with temperature so 845 MCA is equivalent to ~940 A for temperatures in the range 65 oF<T<105 oF, a temperature range outside of which no sane person would even consider riding. The motors draw 480 A total under full load which says the battery should last 940/480 x 30 sec. =~60 sec. before falling below 7.2 V, i.e. for the power to be reduced to 40%. So, perhaps half this time, ~30 sec., can be expected from the DocZ before the motors are too weak and the battery has to be recharged. I haven't used a stopwatch, but this is roughly what I observed today in ~4-5 attempts to start the bike.

Drawing 480 A for 30 sec. is 4 A-hr. so it would take a 6 A charger 40 min. to restore full power after 30 sec. of full load operation. A 20 A charger would do this in 12 min. Since ~45 min. with my 6 A charger is what I actually observed today, and since that is a long time for an impatient person to wait when they want to ride their damned motorcycle, also on order is a 20 A charger, the largest recommended for use with a battery of the A-hr. rating of mine.

As for friction, my fingers are crossing hoping Mr. DocZ gets back to me tomorrow with the answer to my question about friction material. Even with the present power losses on the DocZ, the Competition's wheel comes to a stop when I let out the compression release after which the bare Al roller just spins against the stationary tire.

So, to summarize everything written above, the jetting work is no further along than it was yesterday at this time. Sigh...

Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768412
03/18/19 3:31 am
03/18/19 3:31 am
Joined: Oct 2001
Posts: 1,263
Sydney, Oz
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Shane in Oz Offline

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Originally Posted by Magnetoman
Yes, a direct hard-wired connection would have the lowest resistance, but no way would I consider doing this on a portable setup. With clamps there's hope to knock one free in an emergency.
Have you considered adding a mechanical battery isolator to the circuit? These are often used for marine applications, four wheel drives and big trucks. It will add some resistance, but they are quicker and easier than trying to knock a melting terminal off a battery pole.
A heavy duty solenoid might be an option as well.

Re: Correct needle for 1000-series Concentrics? [Re: Shane in Oz] #768414
03/18/19 3:51 am
03/18/19 3:51 am
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Originally Posted by Shane in Oz
Have you considered adding a mechanical battery isolator to the circuit?
Hmm. I suppose I could have a big red 'disaster' switch hooked to a~500 A relay. But, I'd have to give some thought to the step of making the initial connection to the battery. With clamps there's the possibility for an immediate disconnect but with a separate switch there would be a delay getting to it.

Re: Correct needle for 1000-series Concentrics? [Re: Magnetoman] #768417
03/18/19 6:50 am
03/18/19 6:50 am
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Sydney Australia
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We used to start the booze drinker with a soft plug that was not done up tight, thus lowering the compression a bit.
Once warmed it started quite ( well relatively anyway ) easily.
From cold it would take 3 of us to push then 2 needed to jump on board or the back wheel would just lock up & slide.
Once warm, it would start with little more than its own weight.

Is there enough down force on the rollers ?

Agree with Shane on the solenoid.
Plenty of remote car starting solenoids around that will take 3 minutes of cranking

As for the battery try a spiral wound cell one.
They have a larger plate surface area and more connections between the plate & the busbars.
Thus they can supply a lot more amps for longer than most square plate batteries.

Last edited by BSA_WM20; 03/18/19 6:53 am.

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