Tuning - Original Comet Carb and LM-1 AFR Meter

Pharquarx

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Non-VOC Member
Ok. Here is where I am. Inspected the inlet and the exhaust systems for leaks. The inlet was tight, but the exhaust was leaking at the head to exhaust pipe interface. I took the bike down to Welding Works, they spent about three days correcting the exhaust pipe (correct flanging and diameter, correct geometry for a square interface between the head and the exhaust pipe). The fit up now requires only a single copper exhaust washer/gasket. Went back and set the carb needle midway (the needle is a little bent, but moves freely) and while I was at it, cleaned the internals at the float chamber. There was some permatex goo present and attached to the lower bolt which may explain the difficulty in setting and idle (it would tend to wander - maybe the goo would flow in and restrict some passage and then move out and let the flow through). Once reassembled, the first thing that the carb did was flood.
Set up the air to fuel ratio meter again with the modifications to the sample probe discussed previously. The idle was easy to set now and is pretty steady. Best I could do during these tests was 16.1 afr, which is still lean.
I will go get the larger jets, a new needle and a new float needle. I also have a K&N air filter that I am going to fit up also, one for protection and two, it may swing the mixture to a little more rich.
More will be revealed.
 

Tom Gaynor

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VOC Member
Top tuning tips..

Don't like the sound of that bent needle - might affect your torque curve, ho, ho. Or not.
I don't think it'll make any difference.
Cautionary tale #1: a friend leaned out and leaned out and leaned out a Manx Norton because it kept showing rich. Then it seized. The mag had been failing. So if your experiments direct you a long way away from standard settings, sit down with a beer and consider.
Cautionary tale #2: my twin had been sooty on the front pot since i got it. It became less black after i replaced the guides (no burnt oil now) but was still black. I had run the entire gamut of different jets, needle settings, everything. Then it occurred to me (and I owe the thought to Sid Biberman) that the one thing I had NOT checked, was the float level on the front carb. Rather than do it properly and make a bottom nut with a tube to check that the level was just below the pilot jet (on a 289, but in fact any Amal) I tilted the carb a little. It was better. I tilted it again. It was transformed. Felt just like a bike with two identical pots. Probably through an accumulation of wear, the flot level was about 1/8" too high. Now I run 180's front and rear, needles in same notch (one above the middle) and same #4 slides. And both plugs look the same. (Which is dark white. Which is good.)

Tom
 

roy the mechanic

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Tom, Generally I make you right. The manx showed rich because the weak spark was causing incomplete combustion resulting in excessive hydrocarbon emmissions! Only experience can tell the difference. Come back Ray Petty- all is forgiven!
 

Tom Gaynor

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VOC Member
The guy who takes care of my Manx motor is Gerry Kershaw. Who was apprentice to Phil Kettle. Who was apprentice to Ray Petty...who sat at the knee of Francis Beart.

VOC's "Ray Petty" is Sid Biberman, who (slips back to street-speak) just, like, KNOWS, man. Like, totally. He kept telling me "listen". Eventually, I did. And much later, I heard.

Gaynor's First Law of Vincents: there may be more than one problem.

Let me know what you find.

Tom
 

Pharquarx

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Non-VOC Member
Ok, so after a few months here is where I am. Couldn't get the machine to idle, it kept drifting, so it was impossible to set the rich/lean with any degree of confidence. Finally took it down to Tony at Classic Cycles to see what he could do. He specializes in vintage Triumphs but a lot of the principles for the bikes from that time are the same. Also snagged a really nice second Amal 229/1L2 as a backup for parts. Initially Tony had the same difficulties getting the idle to steady and set the machine aside until the second carb arrived. He selected the carb body that I originally had on the bike and during the course of cleaning up the carb and assembling a single one for installation picking the best parts from each of the two carbs, he discovered that the pilot circuit was plugged. He cleaned that out during assembly of carb intended for installation. He believes that that was what caused the idle to drift, some speck of whatever moving within or occasionally blocking that circuit. When installing the carb onto the bike, he noticed that the clamp at the interface of the carb to the intake manifold would only tighten down so far as the top of the two faces of the clamp where the bolt goes through would touch when the bolt was tightened down. He filed the faces on the clamp so that they would be parallel when the bolt was tightened down, allowing a proper seal. I also noted to Tony that I had to install a strip of pressure sensitive tape around the mating flange on the intake manifold to make sure it would seal with the carb. At first Tony installed the carb without any tape or gasket on this face and all the Comet would do is snap and growl and hiss and backfire when he tried to run it. Removing the carb, he determined that the clearance between the face of the intake manifold and the carb was about 4 thousands. He made a paper gasket and slipped the carb on and tightened the refaced clamp. Whaaaaa Laaaaa - everything fell into place, the idle was steady, allowing the rich/lean to be set - the timing was confirmed at 35 degrees BTDC - was able to push it though it's paces hard - runs like a beast now. Took to to Scotty's on Thursday night and it was a real hit - tomorrow we're going to descend on Cook's Corner. The weather is great here now in Southern California and I am looking forward to a lot of great rides.
 

craig

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VOC Member
Amal 229/1L2 vs 229F/1DV

Hi Charlie, i was trying to follow this Comet Amal thread and I am lost, need help for my own Comet education. I thought Comet used 229F/1DV altho i am looking at 1951-52 Comets. What is a 229/1L2?
The .004 clearance, pressure sensitve tape, mating faces, and paper gasket are not making sense to my understanding of a clip mount Amal. Did the mechanic make a sleeve of paper to wrap the manifold spigot? A tiny ring gasket to fit at the end of the spigot? Or was this leak at the interface between the manifold and head?
thanks for the thread
Craig
 

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Pharquarx

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Non-VOC Member
Hi Charlie, i was trying to follow this Comet Amal thread and I am lost, need help for my own Comet education. I thought Comet used 229F/1DV altho i am looking at 1951-52 Comets. What is a 229/1L2?
The .004 clearance, pressure sensitve tape, mating faces, and paper gasket are not making sense to my understanding of a clip mount Amal. Did the mechanic make a sleeve of paper to wrap the manifold spigot? A tiny ring gasket to fit at the end of the spigot? Or was this leak at the interface between the manifold and head?
thanks for the thread
Craig

Craig, Good morning.
I have attached some photos of the final installation on my Comet. The mechanic made a sleeve to wrap the manifold spigot, that's where the last and final leak was, even after the faces on the ring clip were adjusted, rubber washer on the outer groove inserted, and the clip tightened.
Now, the question as to what a 229/1L2 is - after looking at the literature - you are correct, the Comet was equipped with a 229/1DV - so, the 229/1L2 is, well, the one that is on my Comet (blush). I checked the additional carb that I bought to pull this whole thing together and it is a 229/1DV. In looking at the literature that I do have, it notes that these carbs, while bearing different numbers, are identical except for the slide and main jet. I did have Andy Harden bore the body and manufacture a new slide for the (now noted as incorrect) carb that is mounted on my bike. Don't tell anyone, ok? It still runs like a beast now!!!!!
 

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craig

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VOC Member
Thanks, yes, now i see the white sleeve in picture #3, thank you, nice photos.
What is the rubber washer you mention, i do not see it?
I like the clear oil feed hose, give details. I realize not period correct, but looks valuable during break-in.
I am requesting more photos of your Comet as well please
Craig
 
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