A7SS Carb Question

[zitman]

Hi all,

New here so be knid

I have tried searching but have not been able to find what I am looking for.

I have just finished restoring a 1959 A7SS with a single Monoblock carb.  It starts on full choke but will not tick over at all and will not rev from a closed throttle unless the choke is fully on.  It will not rev through the mid range unless the choke is off!  Adjusting the pilot screw seems to have no effect which would imply to me that the pilot jet, at least, is the wrong size.

Can anyone tell me what jet sizes, pilot and main, needle position etc I need?

Thans in advance.

Z

[A10Boy]

Hi there and welcome.

A few things spring to mind, Is the carb off the same bike, did it run OK before the restoration, if so the jetting is probably right. During the restoration, did you do anything to the carb, if so what did you do?

Have you double checked the timing, is the spark good, as you know, even a faulty condenser can cause these sorts of problems.

The guys at amal can help with jets etc. http://www.amalcarb.co.uk/

[zitman]

hiya,

Thanks for the quick reply.

When I got the bike it was a bit of a basket case and the carb was missing and the magneto was not producing a spark.  I bought a second hand correctly sized carb, of admittedly unknown condition, from an autojumble.  have cleaned it out and jetted it according to some info I got from another, now defunct, forum (Same place I got the carb size from).

The magneto has been professionally refurbished and the timing is spot on and the spark good.

I am going to the show at Bristol at the weekend and was going to pick up a selection of main / pilot jets but I never made a note of the info I got from the other site.

Z

[A10Boy]

From the book, you should have a 1 inch 376, if so, the jets are as follows;

Main Jet      270

Needle jet   1065

needle position 2 [from top]

Throttle cutaway 3 1/2

---------

Be careful not to over-tighten the flange nuts cuz this can bow the flange and cause air leaks

Hope that helps.

[beezalex]

Kinda sounds like the symptoms you get when the needle pops loose.

[zitman]

Thanks for the info and the welcome folks.  I am also in need of a clutch centre for the 6 spring clutch, any thoughts on where I can get one.  I am in the UK.

A couple of pictures:

Before:


After:


Z

[A10Boy]

Well she sure looks very nice indeed.

Whereabouts are you in the UK ?

BTW, do you have a stay to put on the front mudguard ?

[zitman]

Hiya,

I am in Wolverhampton in the West Midlands.  And no I am looking for a front mudguard stay.  And a clutch!!!

Z

[A10Boy]

Not sure about the suppliers in Wolves, but I usually go to C&D Autos near Henley in Arden or Burton Bike Bits of Burton on Trent on 01530 564362 They will sort you a clutch and a stay.

[trevinoz]

If you buy a new clutch centre, I guess you are talking about the piece which mounts on the shaft, be very careful.
I bought two from the UK and they had the wrong taper angle so would not go onto the shaft far enough.
I had them machined to the correct angle but one was buggered in the process.
  Trev.

[zitman]

Thanks guys,

A10Boy: I will try C&D and Burton Bike Bits tomorrow.  I have got my local British bike genius on it at the moment but the more ropes in the boat the better.

Trev: Its the sort of inner clutch basket with the 6 studs attached that the clutch springs go on that I am after (Item 22 in the diagram below).  I did buy one of the boss things that fits on the taper shaft from TMS in Nottingham and it seems OK.



Ta

Z

[LJ.]

Sadly this part (item 22) is a poorly made pressed steel item and nothing like as strong and well made as a solid four spring one.

It would be a good idea to buy your plain plates from the same place so that the fit is near perfect, different manufactured parts may have some slack which would result in quicker worn parts. I've come to the conclusion that the A10 engine is much more destructive with it's clutch parts than the A7. Has anyone else felt this?

Beezealex says:

Kinda sounds like the symptoms you get when the needle pops loose.

Well... Funny you should say this as only yesterday I found my needle had popped its clip and had sunk into the jet. I 'could' not understand why the bike was running like it was! I put it down to the fact that I had been putting some oil into the petrol to help with running the bike in. The oil was straight 50 and with the cold weather the oil thickening up and possibly accumulating in the jets. I flushed the carb out while still fitted to bike and thought I'd lift the needle up a notch, Imagine my supprise to find the 'popped' needle. 

[Richard]

Hi Zitman
I have a few spare 6 spring clutch parts second hand of course, I am located in Wiltshire not far away from Cricklade if you are down this way you would be welcome to have a look and see if one would be suitable.
As well as the spares I still have the complete 6 spring clutch I took of my A10 when I put the George Prew 4 spring clutch on. Now that is a nice clutch and it cost £200 about 2 years ago and went straight on with no conversion needed I would recomend it.

Richard

[zitman]

Hi Richard,

If the complete 6 spring clutch you have is OK wear wise I would certainly be interested in coming to a deal.  Perhaps you can PM me and we can discuss it.

Ta

Z

[ncpierce]

Z

Zitman - bike looks great 

I was wondering where you sourced the paint from?  I have an accident damaged A7 which I need to repaint some bits on.  I have a reliable paint factors but I could really do with a colour/paint code to ensure I get the correct colour.

TIA

Nigel