A couple of problems for unsuspecting norton owners.

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kerinorton

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Feb 12, 2013
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problem 1
Some time ago I asked about fouling spark plugs after about 1000 miles of riding, that seemed to result in hard starting, and that was cured by fitting clean plugs. someone hinted it could be timing, so when i checked, it seemed to be retarded about 10 degrees. I have been riding with my trouble free Pazon ignition system for about 5 years and it was a surprise to see that change. I corrected the timing [ by adjusting the mounting plate ] and after a trouble free run down to the Wellington rally last month, I checked the plugs again today. They were black, and one with a little oil fouling, yet still starting well. A friend had mentioned something about using loctite on the taper to make sure it doesn't slip. I ended up just cranking it up a bit tighter.

problem 2
This one has been mentioned before without saying what it made the bike do.
My bike was running horribly at low revs, and very low throttle opening. It idled most of the time OK. went smoothly above 40 mph but bucked around when throttling off just above the idle position. Only answer at that stage was to just shut the throttle to keep it smoother.
Yesterday I got around to removing the top and bottom of each carb [ Amal 32 ] and although everything was clean, rand the slides looked in great condition, I found one of the main jet bodies had started to undo from the carb body. Originally I had made sure both were tight when I did the work on the carbs about 8 years ago. After fitting everything back together, the bike runs like a dream, even though I know my carb bodies are worn. Fitting the anodized throttle slides was one of the best things I did with those carbs.

Looks like I have once again put of having to buy new premiers.

The only experience I have had with Nortons is with my 71 750, and my 74 850 so have never before experienced problems like these. I am however a retired A grade mechanic, so have a good idea how things should be done properly, which includes rebuilding lots of different engines and all else the goes with keeping cars gong properly. I always believed in keeping ahead of things for my customers so they didn't have problems. That's the problem in itself though, because you don't get to see the stupid shit happening when people don't look after their cars..
 
kerinorton said:
Looks like I have once again put of having to buy new premiers.
Click to expand...
Depending on how much you ride, that may not be as economical as it seems. AMAL has had multiple recent price increases. The dealer cost on a set of premier carbs is 67% higher today than in Jan 2021 and I'm expecting another increase soon.
 
marshg246 said:
Depending on how much you ride, that may not be as economical as it seems. AMAL has had multiple recent price increases. The dealer cost on a set of premier carbs is 67% higher today than in Jan 2021 and I'm expecting another increase soon.
Click to expand...
So what your saying is I could actually sell my pre-2021 Preimers and actually make money? Knew I shoulda bought a truck load back then off you as an investment, could've made big money ;-)
 
If you looked at your plugs and they were black, you might not have been looking at the porcelain. There should be a black ring on the porcelain, right down inside where it meets the metal. If the fuel/air mixture is correct and you are usinng the correct heat-range plugs, the carbon should be burned off the porcelain almost to where it meets the metal. A simple thing such as vibration can cause rich carburation. Carbs need to be rubber-mounted.
 
Tornado said:
So what your saying is I could actually sell my pre-2021 Preimers and actually make money? Knew I shoulda bought a truck load back then off you as an investment, could've made big money ;-)
Click to expand...
The only problem with that is they haven't even filled all my backorders yet to I'm usually lucky to have one or two correct sets for a bike and I'm out of several :mad:

So, good idea that I've been trying to do. I placed a huge order before the deadline for the last 15% increase - haven't even received one of them. For those that get off the pot, I still have some from before the increase.

Our problem remains - too small a community and I think most who want them already have bought them. I haven't sold a single Norton set this year. Here my massive sales of Norton sets for the last four years:

2020 16
2021 17
2022 13
2023 12

And, many of those were for my builds!

It doesn't help that many would like to buy from a big name like the Bonneville Shop or Steadfast who charge WAY more and sell generic sets not meant the bike they are going on! Even AN will cost a US buyer about $100 more delivered than me and they don't include #19 pilot jets and, in some cases, they sell carbs more or less right for the bike but not exactly. For instance, PACK 112 is for a 73 750 but they sell is as right for a 72 Combat and 73 750. Combats get PACK 140. Will PACK 112 work fine for a Combat? Yes, is it right for a Combat? No.
 
On the last trip [ approx 1200 miles ], a rough check told me I was getting between 57 and 68 mpg, depending on the riding conditions. It is reasonable economical, even with the two problems mentioned above. Sometimes I ride a lot and others, like about two years ago where I only did 500 miles between Nov one year and Nov the next. When I was having hard starting after about 1000 miles, the plugs looked pretty clean as per a previous thread..
 
kerinorton said:
On the last trip [ approx 1200 miles ], a rough check told me I was getting between 57 and 68 mpg, depending on the riding conditions. It is reasonable economical, even with the two problems mentioned above. Sometimes I ride a lot and others, like about two years ago where I only did 500 miles between Nov one year and Nov the next. When I was having hard starting after about 1000 miles, the plugs looked pretty clean as per a previous thread..
Click to expand...
Im sure you know this but just in case, looking at plug condition can be a little misleading, as it bike has only been running at low throttle openkngs for some rime prior to checking plugs, you only see what the pilot and needle jets are doing, not the main jet, that would need the wide open throttle chop procedure.
 
A tiny dab of fine valve lapping paste will prevent the timing slipping and not as messy as loctite. It can also be used to lap the two parts together if you seek perfection.
 
I seem to detect a certain mindset in these posts. When you tune your bike - who is the master ? Worn carburetors should not be a problem - the tuning sequence is still logical and does not change.
 
kerinorton said:
problem 2
This one has been mentioned before without saying what it made the bike do.
My bike was running horribly at low revs, and very low throttle opening. It idled most of the time OK. went smoothly above 40 mph but bucked around when throttling off just above the idle position. Only answer at that stage was to just shut the throttle to keep it smoother.
Yesterday I got around to removing the top and bottom of each carb [ Amal 32 ] and although everything was clean, rand the slides looked in great condition, I found one of the main jet bodies had started to undo from the carb body. Originally I had made sure both were tight when I did the work on the carbs about 8 years ago. After fitting everything back together, the bike runs like a dream, even though I know my carb bodies are worn. Fitting the anodized throttle slides was one of the best things I did with those carbs.

Looks like I have once again put of having to buy new premiers.
Click to expand...
the new ones are not immune from loose jet bodies either....
 
Acotel. I am the boss of my bike. Unfortunately, when on a long trip to a rally, you just have to suckit up till you can get where you can sort the problem out if it cant be fixed straight away. Great thinking mate.
 
Never had these issues. Check your valve guides, I figured the carbs were running richer and richer, and then I realized the plugs were slightly oil fouled and it all started adding up. No issues since new guides and valves.

Depending on the model of pazon the advance curve is wrong for a Norton.

I know this is THE contested issue here, but the japanese Refined the motorcycle carburetor.
 
I read somewhere it is impossible to calculate an ideal ignition advance curve. However I suggest the shape of the ideal advance curve must depend on the rod to stroke ratio of the motor, the equation for that can be calculated - then the whole curve shifted to suit the fuel. Whatever the shape of the advance curve might be, it is probably normal to jet to suit it.
I suspect the advance curves which currently being used were probably initially arbitrary, and then improved by trial and error.
When I was building a two stroke, I developed the equation to convert crank degrees to distance of the piston and ports from TDC. I printed-off a table of crank degrees related to distance from TDC. Most high level computer languages use radians instead of degrees. So you need to divide degrees by 57.296
 
kerinorton said:
problem 1
Some time ago I asked about fouling spark plugs after about 1000 miles of riding, that seemed to result in hard starting, and that was cured by fitting clean plugs. someone hinted it could be timing, so when i checked, it seemed to be retarded about 10 degrees. I have been riding with my trouble free Pazon ignition system for about 5 years and it was a surprise to see that change. I corrected the timing [ by adjusting the mounting plate ] and after a trouble free run down to the Wellington rally last month, I checked the plugs again today. They were black, and one with a little oil fouling, yet still starting well. A friend had mentioned something about using loctite on the taper to make sure it doesn't slip. I ended up just cranking it up a bit tighter.

problem 2
This one has been mentioned before without saying what it made the bike do.
My bike was running horribly at low revs, and very low throttle opening. It idled most of the time OK. went smoothly above 40 mph but bucked around when throttling off just above the idle position. Only answer at that stage was to just shut the throttle to keep it smoother.
Yesterday I got around to removing the top and bottom of each carb [ Amal 32 ] and although everything was clean, rand the slides looked in great condition, I found one of the main jet bodies had started to undo from the carb body. Originally I had made sure both were tight when I did the work on the carbs about 8 years ago. After fitting everything back together, the bike runs like a dream, even though I know my carb bodies are worn. Fitting the anodized throttle slides was one of the best things I did with those carbs.

Looks like I have once again put of having to buy new premiers.

The only experience I have had with Nortons is with my 71 750, and my 74 850 so have never before experienced problems like these. I am however a retired A grade mechanic, so have a good idea how things should be done properly, which includes rebuilding lots of different engines and all else the goes with keeping cars gong properly. I always believed in keeping ahead of things for my customers so they didn't have problems. That's the problem in itself though, because you don't get to see the stupid shit happening when people don't look after their cars..
Click to expand...
This is what problem 2 looks like. A couple of problems for unsuspecting norton owners.

Mine happened 3 years after the last time I had the carbs apart. Same symptoms as kerinorton. And both carbs had this condition at the same time! How does that happen? I tightened them up and it's running great. I check them through the bowl drain holes periodically. I'm holding off on loctite for now. I want to see if it happens again first. I carry a 5/16 socket so I can tighten them roadside if it does.
 
Saber said:
This is what problem 2 looks like. View attachment 114951

Mine happened 3 years after the last time I had the carbs apart. Same symptoms as kerinorton. And both carbs had this condition at the same time! How does that happen? I tightened them up and it's running great. I check them through the bowl drain holes periodically. I'm holding off on loctite for now. I want to see if it happens again first. I carry a 5/16 socket so I can tighten them roadside if it does.
Click to expand...
I had it too. Both Amal Premiers at the same time.

Many thousands of miles after install.

I had not checked them at install. Or when I changed jets. Lesson learned.
 
concours said:
I had it too. Both Amal Premiers at the same time.

Many thousands of miles after install.

I had not checked them at install. Or when I changed jets. Lesson learned.
Click to expand...
Violent shakings . Norton Carb (s) should be rubber mounted , not solid .
That said , I have not got around to changing this after many years .
 
Torontonian said:
Violent shakings . Norton Carb (s) should be rubber mounted , not solid .
That said , I have not got around to changing this after many years .
Click to expand...
I've often wondered about rubber mounted carbs on a rubber mounted engine
I've used those rubber mounts before and to be honest I can't tell any difference
But I don't see how the carbs can possibly run smoother and have less frothing on the end of a rubber mount hanging off of a shaking engine
Now if the carbs were bolted to the frame and rubber mounted to the engine I could see that working
 

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