Amal throttle valves

You will end up wasting your precious time on these old slides even if getting prefect cut out mixture as the slides and bores will beat themselves up to leak air till can't hold slow idle. Now is time to examine carb bores to determine if they are beaten bigger to make opinion call on new ANODIZED slides a cut lower/richer then creep up to good idle and off idle response with a file on cut outs. Drawing a file on back side of spray tubes, similar to the 850 notch can give a bit more spunk off idle w/o bothering full flow WOT and allow a bit less cut out for a bit more response down low. Can get some guidance by seeing where pilot jet lands for best idle, ideal being 1.5 turns out but I found can run really well with both carb floats levels off for pilot less than one turn out has worked a treat on my Trixie Combat after just by guess and by golly float bumping to hit the road and diddle to ideal some day some 1000's miles when not got other priorities on my time.

You can always measure the cutaway. I've never found it necessary to file a slide, the other jets are usually enough to compensate for any richness or lean ness problems with a No. 3 slide in most motors. If I found one with file marks, I would replace it. I've seen old TT and GP carbs with the slides cut way up, usually changed to cope with methanol on speedway singles - it is all silly stuff, and usually comes from ignorance about which jets are working and when.

acotrel said:

You can always measure the cutaway. I've never found it necessary to file a slide, the other jets are usually enough to compensate for any richness or lean ness problems with a No. 3 slide in most motors. If I found one with file marks, I would replace it. I've seen old TT and GP carbs with the slides cut way up, usually changed to cope with methanol on speedway singles - it is all silly stuff, and usually comes from ignorance about which jets are working and when.

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Hi,
Cuold you explain what means "file marks"?
Ciao
Piero

pierodn said:

Cuold you explain what means "file marks"?

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Marks from 'filing' (using a file):

You can FILE the cuttaway BIGGER . But you cant file it SMALLER . :lol:

I wish I had only two identical throttles!Ciao
Piero

Old Bloke said:

Piero

I think I understand the question now.

I would not expect the cutaway(arc) to be different between your two slides.
The MB number indicates that the slides were cast at two different foundries(factories), but the cutaway profile should be described by the number stamped 3 on your slides.?

Of course, the accuracy of many parts from the suppliers is often not good, perhaps the slide cutaway has been wrongly marked as a 3?

Could a previous owner have modified the slide?
I think you would be better to have each slide with the same cutaway(arc), so you may have to buy another slide.
If you search for "Throttle slides" on the forum you will see the question was asked before, in 2004, but not really answered.
Peter

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Do not assume that one stamped 3 (or whatever) is a number 3 cutaway slide, it is not unknown for some tight-fisted owners to file the cutaway bigger instead of buying another one :!: