I've covered about 1000 miles this year with a pair of hard anodised slides. On close inspection they show no signs of wear whatsoever. I have a friend who has been running a new Amal all year including a 3000 tour of Europe. His slide is the same - no sign of wear, and a shiny spot or two in his carburetter body. Anodised slides provide the same benefit as a sleeved or brass slide. The use of a dissimilar material for the slide prevents the galling which was the main cause of wear.
Hard Anodized Amal carb slides (2011)
- Thread starter lrutt
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Interesting...............Shame Amal didnt bother to take a close look at Mikuni VMs, which have been using hard anodised slides in pot metal bodies for 30 years or more............would have saved an awful lot of people needing to bin or sleeve rubbish parts which seem to wear out very quickly!
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Ron L said:
Mikuni make both pot metal and aluminium body carbs and have been doing so for many years, with the configuration of the early VM series carbs fitted to Yamaha's in 1964 being I imagine what Amal copied when designing their later Concentric carbs. Pot metal Mikunis are still produced today, and the use of hard anodised billet aluminium slides means there are no problems with premature wear whatsoever.
This seems to suggest that had Amal copied the way Mikuni actually makes carbs as well as the basic VM design, that users of Amal carbs would have had far fewer problems over the years, as there would have been no need to contend with the issues related to shoddily made rubbish, which even today still wears out very rapidly (if not fitted with Mikuni type slides!).
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Ron L said:
All Mikuni pot metal carbs produced today are fitted with hard anodised aluminium slides as they have been from the start. It has only taken 30 years for Amal to figure out the reasons why their pot metals are wearing out, and start selling hard anodised slides at additional cost, when they should have always had these fitted to prevent problems with very rapid wear.
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Just searching carb postings. I have the Amal Premier carbs on my 1975 MK111, the slides are a 3.0 cut away. I am told the cut away should be 3.5 on the 850 MK111. which is correct ? , and if the 3.0 is wrong how does it effect performance? New anodized slides are expensive. I am running a KN air filter and Dunstall silencers with the baffles in.
Thanks, MF
Thanks, MF
Fast Eddie
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3 is richer than 3.5. The slide cut away comes into play ‘just off idle’ so when you first ‘crack’ the throttle.
Most of the time, you simply accelerate through this range quite quickly.
However, around town, you could spend a lot of time in this range.
If it’s rich, you feel a slight hesitation or ‘bogging down’.
I have 3 slides in my 1968 T120 and I am pretty sure they are too rich, I intend to fit 3.5s.
Most of the time, you simply accelerate through this range quite quickly.
However, around town, you could spend a lot of time in this range.
If it’s rich, you feel a slight hesitation or ‘bogging down’.
I have 3 slides in my 1968 T120 and I am pretty sure they are too rich, I intend to fit 3.5s.
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If the slide is really too rich, there will be a chugging 8-stroking effect at a throttle opening just off idle.
If your bike has good throttle response and doesn't foul plugs, the slide may still not be perfect but perfect can be the enemy of good.
If your bike has good throttle response and doesn't foul plugs, the slide may still not be perfect but perfect can be the enemy of good.
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The carbs did not come with the stepped spray tube, and it seemed to be running lean. Will putting the stepped spray tubes in help with the lean condition, raising the needle too ?
I am using stock, the balanced exhaust pipes.
I am using stock, the balanced exhaust pipes.
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I would change one thing at a time. Raise the needles then think about spray tubes. If the bike hesitates and maybe dies as you pull away it's not getting enough fuel, raise the needles first.
And yes I think stepped or chamfered spray tubes gets more fuel flowing.
And yes I think stepped or chamfered spray tubes gets more fuel flowing.
concours
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Didgoo get 'em from Dude?
Mine ran perfect, as supplied. Not sure where he sourced 'em.
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75's are set up a bit different with the OEM balance pipes. Did get them from Dude
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Just to throw in my two pennyworth – I had 3 1/2 slides in my Mk1 Concentrics with stepped spray tubes, and it had always tended to hesitate and bog just off idle. Indeed I once tried 4s, as I suspected richness, but they were much worse; it may seem counterintuitive, but after that, and using this guide from Amal, I decided the 3 1/2s (which by then were hard anodised items) were too lean and changed them to 3s – the result was superb and the change dramatic. Your K&N air filter will produce leaner running than the standard filter, no? And I would go for the stepped spray tubes straight away. As I say, just my 2p, good luck with it.
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Carb problems are more likely to be due not enough fuel. Engines can manage too much fuel a lot better than not enough. Sure the plugs won’t look pretty.
Dell Orto’s and Keihins have accelerator pumps that squirt neat fuel in when you crack the throttle open, this generally being the time the slide moves the fastest. So if the bike pops and bangs on the idle circuit, you need more fuel, (air screw), if it hesitates or dies when accelerating from idle then the needle needs adjusting, (first thing to try)
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3.5 would be the correct original slide but as the air filter and exhaust are non-standard then the original settings won't necessarily be correct anymore.
As mentioned, 3.0 is richer.
"Running lean" but at which throttle position/positions?
With a richer 3.0 slide I would not expect it to be lean in the cutaway range (unless perhaps the float height/fuel level was low?).
The stepped spray tubes* were fitted to standard 850 carbs to cure what was basically a non-existent problem unlikely to be encountered under normal riding conditions.
(*Stepped spray tubes are intended to be used with 928/104 needles.)
My 850 Mk3 with S&B filters, peashooters, generic (300/301) Amal Mk1s runs well with 3.0 slides (anodised), flat-topped spray tubes and standard 4-stroke 622/124 needles, clips in central groove.
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