Right carb mix

Maybe it's me but I can't seem to dial my amals in correctly. They seem to be pretty touchy and it has gotten to the point where I just bring a flat head every time I ride. on some days the idle is fine while others, especially on warmer days, the orange dummy light will flicker and the bike will want to cut out on me. My question is, is there a good "rule of thumb" to get the right fuel/air mix?

Absolutely to the point there is a ancient motto to follow in your case, when it feel and acts like poor fueling problem go straight to the electrics first. Try a fresh full charged battery and if that fails suspect bad connections and/or spark time issues, especially if a boyah. Carb fasteners - air leaks are famous for what ya describe too, damhik. Floats can fill and sink too.

My headlight doesn't dim when I hit the brakes or put the turn signal on so I can rule that out at leased. I only have the cutting out issue at idle when really warm out. There is a slight delay when I hit the throttle which leads me to believe it's the fuel/air mix problem, but who knows maybe I'll clean the points tomorrow and see what happens, I love my Norton and will never sell it, but there are days when I miss my fuel injected Honda CBR but thanks for the input kind sir.

What ignition do you have and where is the timing set?

How many miles on the carburetors?

If the slides are a bit loose in the carbs it can cause erratic idle. A good, quick check is to turn the throttle just enough until the cables barely put tension on the slides. It will stop them from shaking around an the idle should stabilize (usually lower).

But like Mr. Bot said, first ensure ignition is in good shape.

Sounds like stock auto-advance unit. I struggled with mine because it was worn. Ignition timing would never settle at the same place twice down around idle and it lead to erratic idle. You change the carbs to get a good idle, but the next time you rev and go back down, the timing is different and... repeat the process.

My AAU was too worn for me to be happy with it, so I went electronic and am quite pleased.

You may be okay to service the AAU (clean and lube) and reset timing with clean points. It's a pretty good system when all the parts are doing what they should.

Whitworth Ranch said:

Sounds like stock auto-advance unit. I struggled with mine because it was worn. Ignition timing would never settle at the same place twice down around idle and it lead to erratic idle. You change the carbs to get a good idle, but the next time you rev and go back down, the timing is different and... repeat the process.

My AAU was too worn for me to be happy with it, so I went electronic and am quite pleased.

You may be okay to service the AAU (clean and lube) and reset timing with clean points. It's a pretty good system when all the parts are doing what they should.

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Yes it is the stock points ignition, I will check the points out and see how they look. This is my first year as the owner but the guy before me took great care of the bike, although I have already put 1600 miles on it since February it may be time get down and dirty. I was hoping to go through the bike this winter but It looks like it may benefit the both of us with some down time.

If you spend a little time with the ignition, you can probably improve things quite a bit.

If you clean your points, don't use sandpaper. You can use a fine file (very lightly) but this kind of thing is best: http://www.mcmelectronics.com/product/J ... 3-/22-1235

If you pull the points plate, the advance is right there behind it. Clean and lube its pivots, etc. I found my springs and my pivots were worn out, so I went electronic. Reset your points and retime and see where you stand.

Good luck.

I had the same problem when I first got my Commando.Bought new Amals and still couldnt get a decent idle. Replaced the ignition with the Tri-spark unit and now all is well.

If you have to adjust your amals every day and the bike generally dies at stop lights - then they are working correctly.

speirmoor said:

Replaced the ignition with the Tri-spark unit and now all is well.

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Electronic Ignition cured my Amal carb problems too!! 8)

jseng1 said:

If you have to adjust your amals every day and the bike generally dies at stop lights - then they are working correctly.

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Amal hater talk from the man who wants to sell you some other carbs. :roll:

batrider said:

jseng1 said:

If you have to adjust your amals every day and the bike generally dies at stop lights - then they are working correctly.

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Amal hater talk from the man who wants to sell you some other carbs. :roll:

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Loved all my brit bikes with amals on them. Rode em for 30 years. Then one day a customer had me install Ron Wood Del Ortos on his Norton. They hit every single beat on idle. They stayed adjusted. I saw the light (its easy).

Here Here Here, I know what decent Amals are capable of to point i'm not that extra impressed with electric fuel injection. My long lost P!! dragster once started first kick after 9 mo's stuck in a shop we me far away, on return its open headers were up against a Fla. Police Harley white hard bags, gave a tickle and a stiff leg chop down expected the worse but instead BLATT Poofff Poooffff BLATTTT, poofff pooof, to turn grinning for a ear to ear sheet eating one seeing two diner plate size carbon pancakes imprinted on the poor Harlely, so laid on another layer, then idled at 600 rpm like kettle drums out of there till on clear road and gave a bit of welcome home throttle for instant skid sideways as grin built so gave smoother twist so front just floated level then holding WOT tapped the big chrome kill button at same time as toe tap shift for one bounce of front then floating level again wrists straining like ski rope and vision narrowing 9000 rpm tap snick with a light touch down to hang on floating through 9grand then tapsnicktouch float though 5-6000 then front lowered but the pull hardly did, till oustside of town pulling off into Fla sugar sand paths over hill and dale in 4th gear hand off throttle trotting along at jogging speed with front tire parting the deep sand exactly like wake of a boat bow lugging along happy as a lark till a steep appeared then just smoothly grab a hand full for instant hill climber rooster tailing glee over the crest then let going back into trace state of natives beating on big drums into your deep chest. That is the only machine I've never brave enough, even as 21 yr old to see what it topped out at. These Amals also ran at about same canted Cdo angle as the bike was cut down to be 2" low in front. Whats not to love about till of course something wears out. Now with current upgrades Amals can service us fuddy duddies good as a dog under the porch waiting for that rabbit to scare off again.

Norton's are designed to blast down the road, not to idle. A good idle is if it does not die when you come to a stop. I have an old Triumph with old Amals, and she just ticks over like a clock. I have an old Norton with new Amals and she never idles the same twice but never dies and really gets along down the road. I am in awe when I see a video of a Norton ticking over like a Swiss watch. One day I am going to use my newly constructed water manometer to set the carbs after checking the float levels with the little clear tube connected to the bottom of the float bowl. Both are tricks I picked up from the fabulous forums out there.

Nay Nay my good sir I well know of the risk to stop after a run to be stuck in rush hour or dead at bottom of valley, but I'm am so spoiled on two dialed in Combats, if not joy by second kick, mostly d/t half hearted 1st try I stop and find what's wrong before 3rd attempt and secure to idle below charging rpm till stalls out for lack of fire not fueling. Usually forget fuel or key on but once in a while power wash knocked off a connection. OH yeah Trixie with pt's and Amals is 1st kick start with plug holes full and water everywhere including air box paper filter. Ya can live with less of curse and I sure have but its not normal only merely too common.

Do what I did - solder little brass tabs into the screw driver slots of the mixture screws AND the idle speed screws. That way you can fiddle with the Amals at the stop lights to keep them running. Some lucky Amal lover has them now - I sold them on ebay (along with the Mikuni slide upgrade).

I'm ain't sharpest Cdo'r around and well know the handy screw driver to wipe out to try to settle idle, but have been spoiled to point I never have to touch air screw just the thumb screw slide lifters to change rpm for show off slow idle or close to 1000 for real life use for charging and cam lifter oil surfing. Not to denny the flat slides can do the same and give more power just saying some Amals can work quite adequately. One segment of Cdo-doom likes em like the factory issued them is all.

I found an interesting article on troubleshooting tips and some good info on how Amal carbs are supposed to work for all of the Norton novices out there like me. I was also able to get my carbs completely synced and dialed in as of this very moment I am a happy guy. Lucky for me because my Jeep Cherokee decided to blow a brake line on my way home from work today...Always somthin'.

http://sterlingmotorworks.com/amal_carb ... uning_tips

There are many more advanced carburetors than Amals. But Concentrics in good condition with a consistent ignition work very well. Cylinders that hit every time and at the same idle rpm, good response, 50-mpg-plus, etc.

Decemberist said:

terlingmotorworks.com/amal_carburetor_tuning_tips

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Linky no worky?