New member in East London with a problem

[davbr]

Hi, I'm David and very new to any forums (this is my first) so please excuse any forum nievity.
Just signed up though have been visiting as a guest for some time and have found this forum great and very interesting.
I have had a 58 A7SS for about two years and of all the British bikes i have owned (there have been quite a few including other BSA's) I find it the most enjoyable and satisfying to ride. I use it as my  ride to work and barring  a few minor issues it has been pretty reliable.
Now the problem. It starts very easily after a brief tickle of the carb and one or at most two kicks. It then, after a few seconds, dies as though being starved of fuel or it runs very roughly for a bit longer then dies. I assumed problems with the fuel/carb. The fuel is quite fresh i have stripped the carb all passage ways/jets/ filters are clear. Before i start investigating any issues with ignition has anybody out there experienced any similar problems or have any possible solutions or ideas for things i should check?
Any help greatfully recieved, getting fed up using the train to get to work.
Cheers

[bsa-bill]

Welcome David.
lots of good advice to be had here, I'm no expert and have had issues with starting and starting warm, yours though starts ok then stops or runs rough, for my tuppence worth, have you checked the fuel cap, sounds just like the symptoms of a blocked breather hole in the cap, causes a vacuum in the tank, one to check for elimination at leaast 

[davbr]

Thanks
Just checked the petrol cap air hole appears clear, I also tried to start it with the petrol cap removed, problem still persists.
Very frustrating given how easy it starts

[t20racerman]

Could well be the magneto on the way out. Enough of a spark to fire it up, but can't supply thousands of sparks when running. Might be a fuel issue if you are lucky, but sadly I very much doubt if it is that. 

[lawnmowerman]

Hi David and welcome to the forum.

I had a similar problem when I first bought my bike. It would run ok on start up but after a few miles at a steady 45mph the engine would keep cutting and faltering. If I stopped and started up again it would be OK for another mile or so and the same happened again.
I then tried running with both fuel taps open and there was no problem. I then checked the fuel flow through the taps and hardly any was flowing. When I removed the taps and inspected them I found that the rubbers were dissolving and spreading and blocking the fuel flow probably due to ethanol damage. A new pair of taps from SRM solved the problem.
It could be that this is your problem so I would disconnect the fuel pipes at the taps and check flow. If this proves to be the problem may be worth ordering up some replacement ethanol resistant pipe too if it has not been replaced.
Another tip I would suggest is to run the carb dry after each run to avoid gumming up the carb.
Another problem I had was chunks of Petseal in the tank, again dissloved by ethanol, so I flushed the tank as well to get rid of the residue.
Good luck with it

Jim

[trevinoz]

Could be the pilot jet or the passages blocked.
Have another look with a fine wire.

  Trev.

[bsa-bill]

Can't see how it would start Trev with a blocked pilot jet, I tend to agree with T20racerman, magneto, which bit of the magneto is another matter - as I well know

[muskrat]

 Trev could be on the money Bill. Tickle the carb and the motor uses that but then get's squat from the pilot and stops.
 Dave, give it a good tickle and start it and hold down the tickler. Then try to get it up on the slide (1/4 - 1/2 throttle).
 Report back.
Cheers

[bsa-bill]

Right on Muskrat I get the theory now, apologies Tevor

[RichardL]

David,

Generally, if I'm talking about carbs and not asking questions I'm sticking my neck out. You have quite a bit of experience, so if my thoughts here are beneath you,  I apologize in advance. I don't see that you mention which carb you have. In a concentric,  I think it might be possible to reverse the locations of the throttle stop screw and pilot screw. In any case,  it took me a whiile to get an idle setting that was about right,  balancing fuel flow at the pilot with air flow due to slide lift via the throttle stop screw. I suppose these points may be too simple for your troubling problem.  Good luck with it.  Can't wait to hear the real solution.

Richard L.

[RichardL]

Oops. Just re-read the original post. The fact of you riding the bike daily, I guess, completely rules out my amatuer mechanic suggestion of reversed adjustment screws. But thinking about it was fun.

Richard L.

[davbr]

Gentlemen
Muskrat and Trevor were indeed bang on the money.
Just started the bike and got my daughter to hold down the tickler and it did run ok, until her finger got sore and she started moaning about the smell.
So off with the pilot jet which although i had checked the two holes in the side of the jet previously i neglected to check the end which was blocked.
Bike now running fine again.
Thank you all so much for your help/advice and so glad i can put off spending a fortune on my mag!
David

[muskrat]

 Trevor wins the cupie doll, his suggestion, my method.
 David, keep giving your daughter things to do like that. I really like the fact that my SWMBO knows her way around the shed and the difference between a phillips and torx driver.
 Cheers

[davbr]

One last question on this, thought it probably best if i replace the pilot jet now that i have been shoving a piece of wire up it. None of my manuals give the size for the pilot and searching the web i get either a 25 or 30. Can anybody confirm the size i need? Its a 58 A7SS with a 376 monobloc.

[trevinoz]

David,
             Originally the SS had a 30 but do you have the original carby?
If it is running and idling OK with the jet that you have, I would leave it alone.

  Trev.