Time to bury the Amals?

JimC said:

I, too, like the vintage aspect. It just isn't too practical for some Norton owners. For more than a few, their Commandos are daily riders. Ethanol spiked gas has rendered the fiberglass tank useless. The original front disc brake on the 72 and up Commandos was very poor, to be generous. The sizing of the master cylinder bore was way off the mark. Pogoing off a dropped brake pedal wasn't fun. Two piece rear axles should have never been made. The many upgrades and fixes discussed here are pretty desirable if you want to turn your Commando into a reliable, safe, daily rider.

Stock vintage bikes remind me of the old joke about Harleys: 98% of the Harleys sold are still on the road, the other 2% made it home.

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+1.

if you want to use your 1960s/70s bike on the road safely, then you will have to make some changes. If you want to keep it absolutely stock then you just end up trailering it from vintage bike show to bike show.
Back in the day we were always trying to make our new Nortons work better than stock and in 1973, that included fitting Boyer electronic ignitions! If Amal Premiers had been available back then, they would have been fitted, when the standard ones wore out.
My 1975 bike is almost always the oldest bike on the ferry to Europe.

My 77 Mk 111 had SU fitted and looks to have been on it since new (after 32K miles)
Some say this was meant to be standard should production have continued
Hif6 SU is idiot proof and British and well worth a try if you come across one
I pulled it apart cleaned it out and away it went. There was some gunk in it too and I am no carby specialist
There are some posts on the SU but I think it deserves another mention
The SU rarely come up when carb chat is happening. Maybe it is just not regarded as worthy?
If the frame has not been altered it fits the 850. (not sure of earlier models)
Power is fine, vibration is less and mileage can be in excess of 70mpg

I sold a model 18 years ago ,I loved the bike and pig headedly refused to put a jap carby on it , It was incredibly unreliable and often hard to start . The guy I sold it to put a mikuni on it and it ran like a dream , if I had done it I would still own it today . My commando has Keihen flat slides and Tri spark starts and runs beautiful . My mate has an SU on his and it's bloody marvellous , I would have put one on , but could not find a kit .

Hi there
I had the very same problem with my 73 750, the bike would run fine and then around the 50 mile mark it would start to misfire badly, pulling the plugs revealed sooty deosits, put a clean set of plugs in and it started and ran fine for another 50 miles. Tried a few adjustments to the carb(single Amal) a different grade of plug with the same effects, checked the normal Boyer failings and re-soldered the wires onto the stator plate with no change.
I read a thread about the coils sometimes breaking down when they got hot, so I bit the bullet and bought one of RGMs twin output coils and since fitting it 1500 miles ago and changing nothing else the problem has been solved.
Might be worth giving that a try if you can get a hold of other coils?

Mac.

I have about 85K miles on my Atlas with original monoblocs...never had the problems I have heard about (I have my fingers crossed, knocking on wood, and all that other voodoo stuff as I write this). I know I will have to bite this bullet if I live long enough....questions are:

1. what is relative cost to refurbish Amal vs replace with something else?

2. if refurbish by boring and electroplating, my thought is to bore body to true it up, then electroplated slide, then turn slide to fit. Is nickel best metal to plate with? ...or turn slide to true up, then plate bore?

3. how does a machinist hold and turn something complicated as a slide?

I found this on the topic: JSMotorsport Maney 850 85bhp motor.

AlColombia said:

I don`t think what we`re talking about is so wayyyyyy out.I would regard a bike with such a sorted motor in the same way as some of the E-type Jags that are refurbished with modern gear to make them truly useable machines.
I want a bike I can use leaving all the 70,s foibles in the past where they belong!
A bike with modern upgrades on suspension,brakes and motor will be a genuine investment.A usable enjoyable thing as opposed to a pain in the ass.A real piece of automotive history that you can use as your daily driver-That is what I want.If it costs me 10-15k over the next couple of years then so be it!
When I,m done my kids will sell it for a mint and go to university :wink:
Al

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texasSlick said:

2. if refurbish by boring and electroplating, my thought is to bore body to true it up, then electroplated slide, then turn slide to fit. Is nickel best metal to plate with? ...or turn slide to true up, then plate bore?

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I wouldn't put any plating on the slide. More than one report here of the plating going through the engine. Better to sleeve. I think it's about a toss up whether to sleeve/repair than buy a new set of premieres. There is also a tool to re-round the bore that's been shown on this forum.

Re: keeping it vintage is nice, but reliability is nice too. I did enough to mine to keep the original look but used some parts that make it much easier to keep going. Each to his/her own, there's room for all of us.

Dave
69S

Had the same troubles with my 71. Big clue that it was jetting problem was it ran MUCH better on cool\cold mornings. New jet needles and needle jets and careful setting of floats as mentioned by another poster cured everything.

texasSlick said:

3. how does a machinist hold and turn something complicated as a slide?

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A Concentric slide is easy.Turn a mandrel that fits into the bottom part of the slide.Drill and tap a hole in the centre of the mandrel for a screw about 1/8" diameter.
Hold the slide on the mandrel with the 1/8" screw.

I haven't done Monobloc slides,but I think a mandrel would be necessary.

As far as Concentric s and the numbers that were manufactured,Amal must have known about the wear problems but did nothing and the punters put up with it.
Not a bad little earner for Amal.

Premiers in the UK are about £120 each with 20% tax, no tax if you live outside of the EU. Biggest advantage is ability to easily clean out idle circuit. Bike will look stock if that's important to you and new amals will probably work just as well as new round slide Mikunis.

DogT said:

texasSlick said:

2. if refurbish by boring and electroplating, my thought is to bore body to true it up, then electroplated slide, then turn slide to fit. Is nickel best metal to plate with? ...or turn slide to true up, then plate bore?

Click to expand...

I wouldn't put any plating on the slide. More than one report here of the plating going through the engine. Better to sleeve. I think it's about a toss up whether to sleeve/repair than buy a new set of premieres. There is also a tool to re-round the bore that's been shown on this forum.

Re: keeping it vintage is nice, but reliability is nice too. I did enough to mine to keep the original look but used some parts that make it much easier to keep going. Each to his/her own, there's room for all of us.

Dave
69S

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Plating failure such as you describe is undoubtedly due to disregard of compatible metals. I am not an expert in plating, but I have been around it in my professional career. A company I once consulted with, plated zinc die cast parts, very similar to the material of the Amals. The parts were first copper plated, then either brass or nickel as a finish. These parts were subjected to the harshest quality control such as accelerated environmental aging and salt spray....there was hardly ever failures. I think plating the slide is do-able, but I don't know best materials, or whether plating the bores is the way to go. Either way, the end result should be better wear tolerant than the originals, since the problem with the Amals is that both body and slides are of the same relatively soft material. Just saying in case someone else is thinking to refurbish Amals.....

I'd stick with the twin carb set up. Heard lots of good reports about the Premiers as well.
I'm still using the originals on my MKIII and have not adjusted them for 4 years though it is just starting to run rough now, but still starts fine. I believe that there were some poor quality bodies and slides kicking about in the 70's and it is hit or miss as to what you got. I even had a manifold come loose and that was some way from home, the rubber inlet held the carb in just about the right position to keep it running if I was careful on throttle - got me home though.

It might be easier to find hard anodised mikuni slides to fit the Amals and bore the bodies to suit ? I use MK2 Amals with mikuni needles which allow much finer adjustment. I made my own needle jets, however the bike is on methanol which allows much more error than petrol. Getting the needle and needle jet right is fundamental, the rest shouldn't matter so much - even slides which rattle in the bodies.
6DP Mikuni needles are good things when fitted to 34mm Mk2 Amals. The distance from the grooves to where the taper begins is important, and varies with carburettor size - however the diameter of the straight bit is identical to that of the Amal needles (3mm?).

I just put the clean plugs in and,of course, it runs fine; roars into life (more like Brrraaattts) on the first kick. I hadn't considered the Amal Premieres but thats the way I'll go unless I can figure the fouling issue.

And the notes on that are; replaced jets and needles and could not get the thing to run at all. Kept the new needle and put in old jets and and it runs. To complicate matters, I had put in a new Boyer at the same time. So there are a few variables and I haven't run new jets, new needles with the Boyer. The 3.5 slides move freely without too much play so I don't think that's the issue. At any rate, I think loose slides would allow more air into the mixture, leaning it out. Sooty plugs are the cause of my grief.

But with all that, I'm getting tired of dicking around. I'd really like to be able to take it out for a good long ride. And get it back again.

Funny thing is the 68 Triumph seems to be sniggering at me.

BC
71 Commando
68 TR6P
71 Suzuki A100

I've been using Mikuni carbs for a very long time with great success on Brit bikes. They don't wear out and each carb circuit can be precisely tuned. I would strongly recommend the Mikuni over the PWK.

You didn't mention if your tank was steel or fiberglass. If it's fiberglass, and breaking down due to ethanol,no amount of tuning will fix that.....Skip

Here's the advantages of JS flatslides over mikuni.

The JS flatsides come already tuned for Nortons. Lots of customer feed back has gone into refining these carbs. The latest addition is a custom needle jet for leaner running which puts the needle closer in the mid clip position. The PWK flatslide has a slightly rounded curve on the manifold side so they run quiet and do not rattle - other flatslides can have an annoying rattle. Don't even try to compare round slide carbs with flat slide carbs - the flatslide carbs are best.

The single mic carb will starve for fuel at WOT on a nort unless the fuel passages and float is modified like a JS carb. Or it has to be so huge that it won't fit. PWKs from other suppliers don't have these modifications and they can have problems.

It was Amal day today.
A large box arrived from Andover Norton yesterday that included a bunch of Amal parts for the Mk2a.
The carburetors were fuel stained when I got the bike,had no air filter and no adapter rings from carb body to air box rubbers.
The parts cleaned up fine with a little elbow grease,how long could it take to remove a adapter from the packet,put a little never seize on the thread and screw it on.
Two hours it seems with careful scraping of the bodies thread,no wonder they were missing.
One to go.

I have a 1975 Commando MKIII. I have spent a lot of time with my old Amals trying to get them to idle properly. Using Bushmans Carb Secrets I set my carbs up from top to bottom and still could not get a good idle. The bike ran great except for the idle issue I decided to have them re sleeved and replace everything with new components including Stayup floats. I contacted Jerry (Access Norton) about this idea. He suggested the new Amal Premeires. After much emailing and several phone conversations I ordered a new set for my bike.The price difference between a new set vs the cost of repair parts was so small it was worth a shot. It took a couple of hours to swap everything out and set up the cables and slides. The bike started right up, it took less that 10 minutes to set the air screw and idle stops. I have a couple of hundred mile on them now and have not had to touch them at all. The bike is a little cold blooded now and requires the choke to start, but once it is warmed up a little it runs and idles perfectly at 700 rpms.For anyone thinking about a complete rebuild vs new carb, or a different brand I would suggest talking to Jerry. He was extremely helpful and spent a lot of time with me making sure I got what I needed. This is without exception the best upgrade I have made on my bike.

I use 34mm Mk2 Amals fitted with home made needle jets and 6DP Mikuni needles, tuned for methanol. Mikuni needles are usually hard anodised aluminium, so the wear rate is probably better. I suggest the carbs themselves are little different to Mikunis, however Mikuni offer a much better choice of needles, so you can get the tuning closer to the optimum. The sixties and seventies Amals, and Mikunis usually use needles which are 3mm at the parallel part, the tapers are different and it is important to get the correct shoulder height. Tuning at 3/4 throttle is critical.