Author Topic: BSA A7 ss  (Read 5500 times)

Offline Mosin

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Re: BSA A7 ss
« Reply #30 on: 06.04. 2010 21:28 »
Thanks for all the suggestions guys. I was hoping to get the engine to at least run and then conduct further adjustments by trial and error. However, It looks like the way to go it the whole timing disk/strobe thing attached to the end of the crankshaft with some sort of pointer.

This raises a couple of other questions:

  • How does the piston stop work? Do need one?
  • The instructions for my Pazon talk about setting the timing at 3000 or 4000rpm. My A7ss doesn't have a rev counter. How do I proceed?
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline muskrat

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Re: BSA A7 ss
« Reply #31 on: 06.04. 2010 22:32 »
You should be able to use your TDC tool to find TDC. Set up pointer and disc to zero at that point. Mark disc at 34 deg BTDC. Set up the strobe, I use an external power source for it (most are 12 volt). Start motor (warm up first) then increase revs till mark stops moving towards the pointer (thats max advance). Adjust ign so it aligns with pointer.'Set and forget.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Offline Mosin

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Re: BSA A7 ss
« Reply #32 on: 06.04. 2010 22:46 »
You should be able to use your TDC tool to find TDC. Set up pointer and disc to zero at that point. Mark disc at 34 deg BTDC. Set up the strobe, I use an external power source for it (most are 12 volt). Start motor (warm up first) then increase revs till mark stops moving towards the pointer (thats max advance). Adjust ign so it aligns with pointer.'Set and forget.
Cheers

That sounds simple enough thanks... All I need to do now is get the thing to run so I can try it!
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline muskrat

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Re: BSA A7 ss
« Reply #33 on: 07.04. 2010 00:25 »
G'day again Mosin,
                         just re-read your post. set it at the other hole. The shaft spins anti-cw looking from the timing side but cw looking from the primary side.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Online BSA_54A10

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Re: BSA A7 ss
« Reply #34 on: 07.04. 2010 08:47 »
If you haven't done so yet. try new plugs.
I have had bikes that warmed up beautifully while I was getting my riding gear on, then stopped and refused to start.
Never had time to do a full "Sherlock Homes " on it so I took either another bike or the van.
In each & every case when I replace the plugs the bike ran like a clock again.
I have had brand new plugs straight out of the box go bad in less than 10 minutes.
Brand of plug dose not seem to make a difference.

Another club member & I went out for a "shake down" on his new Bonnie.
It ran like a top, he turned off the fuel taps let the engine drain the bowl.
The next morning it point blank refused to run on both sides, alternatively running on one side then the other. Pulled the plugs out of the Firebird & gave them a try. The Bonnie never missed another beat all weekend. Both of the "bad" plugs fired quite well when out of the pots and earthed out on the head but would not run reliably in the pots.
Bike Beesa
Trevor

Offline Mosin

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Re: BSA A7 ss
« Reply #35 on: 08.04. 2010 11:16 »
G'day again Mosin,
                         just re-read your post. set it at the other hole. The shaft spins anti-cw looking from the timing side but cw looking from the primary side.
Cheers

You are absolutely right Muskrat! This morning I set it to the correct hole (clockwise one) and it fired up second kick! My fault for being influenced by the Pazon Literature which suggests that BSA Twins shgould be set to anti-clockwise rather than trusting my own eyes!

As a slight downturn, after riding it around the yard a couple of times to get it warm and the oil circulated I lifted it onto the centrestand which promptly snapped. Hey-ho, at least she runs!
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline muskrat

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Re: BSA A7 ss
« Reply #36 on: 08.04. 2010 14:00 »
Good one mate, still do the degree disc thing. No more ign probs, just stands,carb,guides,nut that holds the handlebars  *smile*
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

IanH

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Re: BSA A7 ss
« Reply #37 on: 04.05. 2010 16:57 »
Ha..the age old A series starting probs.

I spent thousands on a host of NOS parts from the US recently on my A7SS. Did a lot of advanced engineering to the crank, and just about every moving part within. Cleaned the tank with phosphoric acid, the works. Everything new.

Started around 3rd kick from scratch...beautiful. Sounded sweet as a nut. I took it for a gentle 5 miler to start with, no probs and over the next few weeks gradually increased the miles with no probs.

Then one evening I was 30 miles from home and noticed a cough..Did a quick check of the fuel cap for a blockage but it was nice and clear and headed straight home. Well, the last 10 miles were touch and go, it was awful, coughing and banging..AAAGHHH!!!.. Im sure you all know what I mean.

Anyway i went through the whole checking process as we do finally pointing the finger at the, yeah you guessed it.. the Magneto!.

There are  quite a few reasons why an A series wont start but I think the Mags are terribly problematic.

Mine was rebuilt during the build but I took it off and got another "expert" to take a look. He spotted immediately a prob with the condenser, though apprently worn bearings can cause havoc with dwell angles and so forth I was told. Anyway I popped it back and the bike has run flawlessly ever since.

Of course that doesnt mean other things are necessarily ok. On the subject of dry plugs. If they are dry then that can point to all manner of... carb sealing/barrel/head/compression probs.

Owning an old bike is a tricky business. You have to get your head into all aspects of it and learn more than you ever thought possible cause there's always going to be something that will catch you out.

But I would certainly recommend a mag check. They are in my opinion the achilles heel of what is a great piece of old time machinery.



Offline Ianm

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Re: BSA A7 ss
« Reply #38 on: 10.05. 2010 17:01 »
Hi.

Well i am really glad that we are all able to air our running problems through this site. I have still no answer to my original problems and i think i need to get the Mag checked even though i have only had it refurbed recently.

Has anybody else used Steve at Sussex Magneto@s he advertises in OBM?

Cheers

Ian.

Offline muskrat

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Re: BSA A7 ss
« Reply #39 on: 10.05. 2010 20:58 »
G'day Ian,
              funny how posts wander.
sounds like you still have carb probs. what type and jet sizes is it ?
Another member got a mag rebuilt but found probs with it as well.
I.m in Oz so can't help with an expert over there.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7