amal slides

montelatici said:
Never had any problems with my original AMALs since I bought my Norton 35+ years ago. Have rebuilt the engine twice, but same carbs and slides only replaced for tuning purposes maybe after the last rebuild 10 years ago. Amals wear out when people over torque the carb falnge and get the carb body out of round, full stop. That's why I am skeptical about all this hocus pocus. By the way, I have forgotten more about Norton mechanical issues than you will ever learn, so keep this "I don't think you get it" crap to yourself.
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You must have been lucky enough to have got a bike fitted with some of the very few Amal carbs not to have been made out of very low grade lead/zinc/alloy pot metal, which results in carbs which when used in serious competition applications need to be replaced every six months!
 
I would NOT use chrome slide's again. I have Sean the chrome come off and if they are the zink w chrome they will also break out a chunk on the engine side of the slide. the next set I might try the brass non plated of IF the anodized are NOT zink they might be worth looking at.
 
bill said:
I would NOT use chrome slide's again. I have Sean the chrome come off and if they are the zink w chrome they will also break out a chunk on the engine side of the slide. the next set I might try the brass non plated of IF the anodized are NOT zink they might be worth looking at.
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I wonder if the chrome coming off is an isolated incident because I have not heard of it on other carbs with chrome slides. Aren't mikuni slides chrome plated and I think the pwk slides are chrome as well. I would think if it was an issue companies would stop using chrome plate, but as it stands now I will at least try the chrome on one bike to see how it works out.
 
Just emailed Burlen regarding my order for a chromed brass slide (two months and still not arrived), here is their reply:

We apologise for the delay in our response. I’m afraid we have not got 928/06035HC in stock at present, we can however offer a substitute of 928/06035HA.

Unfortunately it can be weeks possibly even months, before 928/06035HC comes back into stock due to resourcing problems.
Please again accept our apologises for the delay and inconvenience this has caused to you.

Kind Regards,

Customer Services
Customer Services Advisor
 
My opinion in this matter is hardly worth notice, but to my mind there is one potential advantage to a brass slide in that it will weigh more. This might traslate to less rattling in the bore and thus less wear. Couple that with a smooth chrome surface and I think you will get less wear. Are they worth putting them into carbs that already have a worn bore? I dunno.


Russ
 
Russ, I'd agree if the body is severely worn. As it is I put a new standard slide in an older body, not terribly worn and I am getting good results, nice idle, responsive performance as expected, better than the worn slide. I initially started this thread to find a vendor for chrome plated slides in an effort to curb wear which I firmly believe will happen with two metals that are different. Ultimately I think a new slide of better material or different material will perform the same, but will not wear as fast.
 
rvich said:
My opinion in this matter is hardly worth notice, but to my mind there is one potential advantage to a brass slide in that it will weigh more. This might traslate to less rattling in the bore and thus less wear. Couple that with a smooth chrome surface and I think you will get less wear. Are they worth putting them into carbs that already have a worn bore? I dunno.


Russ
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Not to mention better response when you rapidly come off the throttle... the weight assists the springs in pushing the slide back down...
 
Once again i learn something new everyday from this site. I'd never heard of Surrey Cycles or of the stay up float kits which, from the sounds of it- i'll be needing. thanks Cj

by L.A.B. » Tue Apr 05, 2011 1:27 pm

Surrey Cycles
 
It is common for soft metals to "pick up" grit which becomes embedded in surface of the soft metal. The soft metal acts as if it were a tool holder, holding that piece of grit up against what ever metal is on an opposing surface.

With motorcycles, the most common areas where this causes maintenance is with carburetor bodies/slides and swing arm pins/bushings.

With carburetors, where the body is softer than the slide, the best way to deal with it is to make the slide harder than the grit.
With swing arms, where the bushing is softer than the pin, the best way to deal with it is to make the pin harder than the grit.

In both cases, hard chrome is a good choice. In both cases, the hardness of the grit embedded in the surface opposing the hard chrome actually can stop the wear of the grit embedded surface, the grit can't cut the chrome and the chrome can't dig out the embedded grit. Stasis achieved.

The same thing can happen with an aluminum anodized slide - the anodizing is as hard as or harder than the grit.
 
The hard anodised slides from Amal have been available for the last six months. I have had a pair in my 66 Bonneville during the last 600 running in miles with bellmouths. There are no marks at all on the slides and some polished areas in the carb body. They are slightly lighter than the zinc slides but are much smoother to the touch and even appear to offer less resistance than the chrome slides I have. (by the highly subjective and non-scientific method of rubbing a finger over them!)

Last year Amal were selling chrome brass slides of the same design as the anodised version - turned from brass bar and with a decorative chrome finish. They still have these in certain sizes but they intended to change them to ground hard chrome brass slides this year. Unfortunately the chroming company have said they cannot meet the tolerances required and Amal are now looking for another company to do the work - which is why the ground hard chrome slides will not be available for a while.
 
As the tooling used to make Amal carbs is pretty much all completely worn out, I wonder why there is any great concern over tolerances? For anyone looking to do a top class restoration, its far better to try and find a pair of NOS Amal carbs from as long back as possible, as these are going to be far better than the ones being sold today, simply due to the tooling being less badly worn.
 
If you ask Amal they say;

“Since we acquired Amal in 2003 we have been working continually to replace the inherited tooling and improve the quality of the carburetters. New tooling for the 900 Series carburetters was introduced in 2008. New tooling for 376 and 389 Monoblocs has been introduced this year. New tooling for the 600 Series Concentrics, 2900 Series Mark 2 carburettors and 375 Monoblocs is currently being made and we are waiting to see the first samples produced from it. The 375 carburetter has not been available since the 1960s. Hopefully the new carburetters will be available later this year. 2000 Series Mark 2 tooling will follow shortly.

With the use of modern CNC machinery all tolerances have been tightened up where possible on the original limits, except where they are fundamental to the performance of the carburetter.

At the same time we have an ongoing programme of development of the carburetters which has resulted in products such as the new floats and slides and the re-introduction of many Amal parts that have not been available for years. The 900 Series castings are now passivated, a form of anodising which improves resistance to wear which can be recognised by the slight “oily” sheen to the metal when new. A further modification for 900 Series carburetters is imminent which improves idle circuit metering and access."
 
If thats the case it seems strange that NOS Amal carbs seem so much better than those produced currently?
 
Carbonfibre said:
If thats the case it seems strange that NOS Amal carbs seem so much better than those produced currently?
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I assume you have both in your hands to compare?
 
Have had ................but how quickly the recently made Amals wear out in comparison to OE ones, tells you a great deal!
 
Carbonfibre said:
Have had ................but how quickly the recently made Amals wear out in comparison to OE ones, tells you a great deal!
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If one was buying new Amals, wouldn't it make sense to go the extra yard and get chromed brass slides, and thereby extend the service life of the new carbs in comparison with OEs?
 
Carbonfibre said:
tells you a great deal!
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Like what? Are they made of different zinc, or do they start out with a bigger clearance?


And please just answer what you've been asked, in brief factual terms.
 
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