Another Norton resurrected

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There may be adjusters on the carb tops also, then the cables may be too short...
 
You said earlier that the idle had to be high for the bike to keep running. I'd guess that's why the throttle screws are turned in so far.
Normally, the slides can come all the way down. But again, if the pilot jets (inboard of the "mixture control screw") are clogged, it won't idle anyway. Those jets must be physically cleaned out, as mentioned earlier, to permit idling.
 
I'm wondering if it would make more sense to try to re-build two 44 year old carbs that have been sitting idle for 27 years or just buy two new Amal Premier carbs.
 
N0rt0nelectr@ said:
Depending on the twist grip there are 2 sets of throttle cables. The 1/4 turn throttle has different cables than the standard one.
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It's the upper section cable inners that are different lengths, the lower cables are the same.
 
Just pulled the right carb off. I don't even have it apart yet but right away I noticed that the needle has a noticeable bend in it about where the taper starts. Should there be a bend at that point, and, if not, what effect would a bent needle have? Thanks to everyone again for the suggestions.
 
I still haven't been able to lower the slides in either carb to the fully closed position. There is still a gap of about 3/16" between the bottom of the slide cutout and the bottom of the carb opening. I've adjusted the cable adjusters on top of the carbs as far as they can move. Throttle set screws are backed all the way out. Is it possible that the cable itself is the problem. ie. too short?
 
WEM said:
Is it possible that the cable itself is the problem. ie. too short?
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Certainly not impossible so I suggest you remove the slides and lower cables and measure the inner and outer cable lengths.
 
Another quick check on proper cable length:
Take off the throttle twist grip assembly (just two screws to undo) and remove the cable.
See if the slides drop to the bottom of the carb mouth now.

(Er, your aren't mistaking the slide cut-away are you?)
 
Improper re-assembly can easily result in a bent needle if you force the issue.
 
WEM said:
There is still a gap of about 3/16" between the bottom of the slide cutout and the bottom of the carb opening.
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At the cutout? Is this as seen from the air filter side? If so, that's correct; the slides bottom out on the intake valve side, NOT the air filter side. If you're seeing 3/16", that would jive with a #3 slide (3/16").
Now, when you say it won't idle down, is that because you're out of adjustment, or is it that the engine dies as you try to adjust it down? If the latter, then my money is on the previously described plugged idle ports. 'Same thing on my '74 after sitting in a storage unit for a quarter century.

Nathan
 
Some really good points raised here. Thanks very much to everyone. I really appreciate the advice.
1. I am in fact looking at the carbs from the air filter side so it may be alright after all if 3/16" is the expected gap. When the carbs drop, they actually do seem to bottom out solidly on something. They probably are bottoming on the manifold side of the carbs. Sorry about the confusion. It's kind of embarrassing actually.
2. I had the carbs off this winter and didn't notice the bent needle. They went back together easily at that time. I recently had the bike in the shop to have a mechanic diagnose the idling issue. Apparently, the carbs were on and off a couple of times during the process. No mention of a bent needle.
3. I'm going to disassemble the carbs and try cleaning them, especially the pilot air port which seems to be regularly mentioned as a chronic problem issue.
I'll post the results. Thanks again to everyone.
 
I hate to see you put a lot of effort and expense in those carbs, just to find out that they are actually worn out. The bores can wear to an oval shape, the slides wear down, the slides can get cocked in the bore and stick open or closed, etc. I normally don't get in a hurry to spend someones else's money, but the new Premiers are not that expensive, and if you look them over carefully to make sure the mains are screwed all the way in, that there is no assembly grease stuck in the pilot jets, and the needles are set the same, you can hopefully move on to other issues. I shd mention that several folks have reported better results with #19 jets, as opposed to the standard #17 's.
http://amalcarb.co.uk/carbspec/carburettor/spares/id/6434/
If you are committed to the old pcs, definitely get new needles and needle jets, and also follow the Amal instructions regarding fuel level for the float adjustment.

Looks like Amal is out of stock on the 19 jets, but this outfit has them:
https://www.ebay.com/itm/Amal-Premi...+pilot+jet&_from=R40&rt=nc&_trksid=m570.l1313
 
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A couple of points about the bent needle issue:
Firstly, what would cause a needle to bend? Has anyone ever seen this happen? and,
Secondly, if the needle is bent, would that mean that the needle jet would also be out of alignment?
 
I would expect that if the needle is bent it would be wearing on the needle jet. I would think that replacing both needles and both needle jets. If you replace one side but not the other there might be problems in how the engine runs right side to left side.
 
I purchased new Amal 932 carbs. When I took one of the new carbs apart for mounting purposes, the factory setting for the needle clip is on the lowest groove of the needle. Should it be on the middle groove instead? I thought that lowering the clip would make the mixture richer. I guess my questions are does it matter which groove the clip goes on? And should I move it to the middle groove?
 
WEM said:
I purchased new Amal 932 carbs. When I took one of the new carbs apart for mounting purposes, the factory setting for the needle clip is on the lowest groove of the needle. Should it be on the middle groove instead?
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Assuming the carbs are original 850 specification with stepped spray tubes, 4 identifcation ring (928/104) needles and 3 1/2 slides then the clip in the third (richest) needle groove is correct according to the Amal list.


WEM said:
I thought that lowering the clip would make the mixture richer.
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It does.


WEM said:
I guess my questions are does it matter which groove the clip goes on?
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Yes.


WEM said:
And should I move it to the middle groove?
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I suggest you try it as it is. If it is too rich, then lower the needles and test again.
 
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LAB, thanks for the quick response. Really appreciate it. The new carbs do have the stepped spray tubes, 4 ring needles, and 3 1/2 slides. I just took the other new carb apart and the clip is also in the third or lowest groove in that carb. Based on two,new factory built carbs and your confirmation, looks like the third groove is the correct position. Now on to installation. Many thanks.
 
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