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Villiers 32a Engine with Amal 626 Carb Fitted to F/B Trials Bike

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Villiers 32a Engine with Amal 626 Carb Fitted to F/B Trials Bike

Post  peter@dunfordconstruction on Thu Mar 17, 2016 10:29 am

Does anyone know or have the above that is working properly?

I would like to find out the correct specification for the Amal carb e.g. as I am having problems tuning mine.

Throttle cutaway size No?

needle jet size

main jet and does it have to be with angled top or flat?

Peter

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626 carb settings

Post  piston 197 on Thu Mar 17, 2016 1:24 pm

Peter, the only figures I have for a 626 on a Villiers engine are for a Greeves THS or TJS, both of these used Greeves alloy barrel on a long 2" approx. manifold
the settings were
main jet 140
pilot jet 25
needle taper jet .106
needle groove 2
slide No 2 1/2

The brass bush that protrudes into the venture diameter would have been angled rather than flat
These figures May not be totally accurate for your set up, but would be a god starting point ?
JH
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My Cotton Trials...

Post  ChrisTurner on Thu Mar 17, 2016 1:40 pm

... with a 32A engine used the following settings which gave easy starting and trouble free running, including a reliable tick over.

Amal Concentric Carburettor setting for Villiers 250 Trials Engine Bore - 1 1/16", Pilot - 20, Cutaway - 3.5, Main Jet - 400, Needle Jet - 0.106, Needle Position - 3. These settings were as recommended for a DOT 250cc 1962 Trials. Chris
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1962 DOT

Post  piston 197 on Thu Mar 17, 2016 2:24 pm

Chris, the figures for the 1962 DOT refer to a 1 1/16" Monobloc Carb,
Peter was asking about jetting on a 626 Concentric ( 26mm Carb) the Concentric was not produced until 1965,
Totally different instrument and set-up. Also with a 400 main jet surely that must be for the scrambles engine rather than the 32A trials lump ? Seems massively over large ?
JH
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Villiers 32a Engine Amal Carb

Post  peter@dunfordconstruction on Thu Mar 17, 2016 8:28 pm

Hi john & Chris,

Thanks for reply.
I have taken carb apart and the following are fitted.to Trials 32a Amal 626/303/prem/A
1. Main 160
2. N/jet 106
3. Pilot RJ 19
4. Choke Valve 3.5

The following are fitted to the Scrambler with 36a engine with a Dot type Barrell & Head (Marcelle) alloy
Amal 626/303/A.

1. Main160
2. N/jet 106
3. Pilot 25
4. Choke Valve 3.5
This one starts & runs very well but of course is much higher compression ratio.

Bit of a conundrum!

Peter



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Villiers32a Carb

Post  peter@dunfordconstruction on Thu Mar 17, 2016 8:30 pm

Sorry I forgot to say both main jets are flat topped not sloping as advised by Amal as neccessary for 2 strokes!

Peter

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Not necessary ?

Post  piston 197 on Thu Mar 17, 2016 8:42 pm

Generally the brass tube in Amal carb is slanted on two strokes ?? presumably Amal know what they are on about >
Suggest swapping the carb that runs well onto the other engine, if that solves problem , then there is something wrong with the carb that does not run well ( usually the .016" drilling ( No. 78 drill) through the pilot jet hole which exits vertically to the carb venturi and almost impossible to clean, as Amal plug this drilling with a brass plug visible from inside the float bowl ) Early Concentric carbs actually have a jet screwed in here which can be cleaned, but Amal in their wisdom did away with it and plugged the access to the hole after drilling with a pressed in blanking plug and the hole blocks up or furs over as it is so tiny. Symptoms of this is poor tickover control and poor running at low revs, but ok from 1/2 throttle onwards .

If you google " notes on rebuilding the AMAL Mark 1 carburettor" there is a step by step pictorial guide including a lovely picture of the removable pilot jet, that they did away with
JH
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Villiers 32a

Post  peter@dunfordconstruction on Sat Mar 19, 2016 3:01 pm

Thanks John, BIt of bedtime reading 16 sheets! Do you think I will get my City & Guilds when I have studied it?

Regards

Peter

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C & G exams

Post  piston 197 on Sat Mar 19, 2016 3:23 pm

Yes should think so, going back a bit that, I did mine as part of my apprenticeship and for 2 years after finishing the apprenticeship in my own time in the evenings at West Glos. college of FE (Mechanical Engineering)

Back to carbs, personally I do not rate the Amal concentric very highly.
In their own overhaul notes it says the two stroke carb has the removable pilot jet and shows a lovely picture of it, but the carbs supplied now , no longer have this, just a pressed in brass blanking plug , making cleaning the 16 thou hole hidden below almost impossible, and with this blocked it will not run right from tick over to about 1/3rd throttle, and as the hole is so small it does not take much to block it, just leaving old fuel in the carb will block it in a couple of months .
JH
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Well there is a funny thing!!

Post  john87 on Sat Mar 19, 2016 9:07 pm

Well well, small world!!!

As part of my collection i have a cincinatti dividing head i am part way through restoring. It carries a brass plate stating that it was; "Presented to West Gloucester college of further education by Rank Xerox, 1975"

The handle is missing.. Do you know where it is????

john...

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Dividing head

Post  piston 197 on Sun Mar 20, 2016 5:06 am

I did my apprenticeship with Rank Xerox, started in September 1972 went to West Glos college for 13 weeks in each year from 1972-76 and then for an afternoon and 2 evenings for 1977/78.
Bet I used that dividing head, can't remember what I did with the handle ?
JH
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Re: Villiers 32a Engine with Amal 626 Carb Fitted to F/B Trials Bike

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