Author Topic: BSA A7 ss  (Read 5497 times)

Offline Ianm

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BSA A7 ss
« on: 16.02. 2010 13:14 »
Hello.

I am in need of some technical help with the A7 i have.

I recently had the Magneto restored as the bike was hesitating after 45min of riding. So i then went to replace it and noticed that the mag pinion gear was missing a tooth, so got a new one( Manual adv/ret) i then put bike back together and it ran very lumpy. Thinking i had the timing wrong i rechecked the timing and valve clearences. The bike would now not start at all.

I have now this morning reset the valves which were not that bad. and the bike did start but with kicking it over 20 or so times.It will now just run for a couple of seconds then dies. I had the lever for the adv/ret fully forward when setting the timing and i have checked there is a strong spark and there is fresh fuel in it.

Can anybody Help as i am unsure where to go next.

Regards.. Ian.

Offline A10Boy

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Re: BSA A7 ss
« Reply #1 on: 16.02. 2010 13:46 »
This is one of those difficult ones to sort out.

My advice would be to re-check everything you have done, don't touch any other setting until you are happy with things you could have changed.

On the basis that the engine ran [albeit for only 45 mins], there couldn't have been much wrong with it - so therefore whatever the problem now is, it must be related to whatever you have done recently. If you adjust other settings before you have found the problem, you wont know where you are.

Re-reading your post, it seems that apart from the ignition timing, all you have done is check and set the valve clearances, you haven't touched valve timing have you? If you are happy with valve settings, it must be a problem with ignition timing, are you sure its set correctly? Go back to basics, things like making sure you know that the engine rotation is clockwise from the RH side of the bike, therefore BTDC is TDC rotated anti clock - things like that. Apologies if you know all this, but people have been known to make those mistakes. get a manual if you dont have one and follow it to the letter.

Check other basic things without changing settings, do the plugs get wet from petrol after a few kicks? You should try new plugs, check the HT leads and pick ups, get rid of resistor caps if you have them etc. good luck, let us know how you get on.

Andy
Regards

Andy

1960 A10 - Black Golden Flash
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1974 Kawasaki Z1a
Yam XJR 1300

Offline Ianm

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Re: BSA A7 ss
« Reply #2 on: 16.02. 2010 14:19 »
Thanks for the reply.

I have not touched the valve timing. since i have last posted, I kicked it over and it did start but with the Adv/Ret lever fully forward which i belive to be advanced and to keep it running i had to have the throttle 1/4 open.

 it splutered and then backfired and then would not start.  I originally thought when it would not start at all  there was a problem with the cam ring spining compleatly around in the mag housing as the bell end on the Adv/Ret cable would not hold it in place. This now looks sorted as i have put location checking marks.

I think i am going to need proffesinal help soon, Just not sure weather for the bike or me !


Offline a10gf

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Re: BSA A7 ss
« Reply #3 on: 16.02. 2010 14:37 »
Quote
I think i am going to need proffesinal help soon, Just not sure weather for the bike or me

Applies to everyone here ;) Welcome to the forum.
e

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

Offline Ianm

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Re: BSA A7 ss
« Reply #4 on: 16.02. 2010 14:42 »
On the point of professional help does anybody know who would be a good workshop/mechanic to contact in the Farnham-Surrey area.

Cheers.

Offline flashblack

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Re: BSA A7 ss
« Reply #5 on: 16.02. 2010 15:14 »
Hello and welcome, i can`t answer your question of a surrey based mechanic, but i will say don`t give up yet!  There is a wealth of "professional help" right here on this forum, just ask any question and you will get plenty of answers, and i`m sure you will eventually crack it.
regards Rich.
build it, ride it, live it!

Offline Ianm

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Re: BSA A7 ss
« Reply #6 on: 16.02. 2010 15:44 »
Thank you for the warm welcome all replys are much apriciated....

Offline LJ.

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Re: BSA A7 ss
« Reply #7 on: 16.02. 2010 17:36 »
Hi Ian... Nice of a younger chap to own an A7 and indeed to join us here. As Flashblack Rich says... Dont give up yet. The problem is likely to be simple and its a great learning curve with satisfaction thrown in when you eventually crack it. Professional fixing is great if you have deep pockets but they never learn anything. Just ask away and have some patience and you'll get there. Good Luck!
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Online bsa-bill

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Re: BSA A7 ss
« Reply #8 on: 16.02. 2010 19:00 »
Hi Ianm
Like Andy I apologise if you already have the knowledge

I have not set ignition on anything other then Advance and retard units and they have to be set with the bob weights jammed into fully advanced position, I assume the magneto with A/R via cable will need to be set in the full advanced position too, which would mean having the advance retard lever in full advance when you set the ignition.
Sorry again if you know this but it's not mentioned in the post's anywhere

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline muskrat

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Re: BSA A7 ss
« Reply #9 on: 16.02. 2010 20:04 »
G';day Ian,
               sounds like there might be confusion as to which way the lever is to give full advance. To advance, the cam ring needs to go in the opposite direction to the rotation of the points.
Your description sounds like timing or something amiss in that department.
Cheers
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Offline A10Boy

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Re: BSA A7 ss
« Reply #10 on: 16.02. 2010 20:24 »
Ian,

Dont give up. The first thing to do is relax. I find that if something is getting to me, I leave it for another day, and often it all seems so much easier.

You will find loads of experience and some great help in this forum, and you can search for info using the search thing above which is a great tool. Also, there is a load of info, manuals, service sheets posted on various site which is a help.

It sounds like you are getting there if you've found a problem with the cam ring / cable nipple fitting, once you got that sorted it will be necessary to re-time it and it will probably be ok.

My advice would be to carefully and calmly think through every operation and part of setting the timing maybe do some research on the net if you are unsure, you wont need commercial help.

Remember what Muskrat said "To advance, the cam ring needs to go in the opposite direction to the rotation of the points." and also the engine rotates clockwise looked at from the RH side.

How are you setting the timing, are you using a degree disc or using a measurement, what degree/measurement are you using?

It needs to be 5/16 BTDC or 33 degress BTDC. Or at least that's a good starting point.

Describe how you are doing it if you want, we are here to help.

Good luck
Regards

Andy

1960 A10 - Black Golden Flash
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1974 Kawasaki Z1a
Yam XJR 1300

Offline flatdeck

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Re: BSA A7 ss
« Reply #11 on: 16.02. 2010 20:35 »
Hi Ian, I notice you say the following ...
"I have not touched the valve timing. since i have last posted, I kicked it over and it did start but with the Adv/Ret lever fully forward which i belive to be advanced and to keep it running i had to have the throttle 1/4 open"
Shouldn't it be retarded when starting ?
Dave
p.s. I'm not confident I know what I am talking about ... ever :-)
Dave
NZBSAOC
1949 A7 Star Twin
Kent, U.K. then Auckland, N.Z.

Offline Ianm

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Re: BSA A7 ss
« Reply #12 on: 17.02. 2010 09:33 »
I think that i need to possibly look at the position of the Adv/ret lever and what it is doing in relation to the contact breaker direction. as i did start it with the lever in what i think is fully Adv position?


I will have another crack when i get home tonight.

Cheers Chaps.

Online BSA_54A10

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Re: BSA A7 ss
« Reply #13 on: 17.02. 2010 12:51 »
Assume that every thing is wrong then start from the top.
1) confirm the points gap. .001" = 2 deg of rotation ( very roughly )
2) rotate engine till points just open and check the piston drop making sure that you are measuring BTDC ( piston rising ) and not ATDC.( piston falling ) . We have all done this at least once.
3) confirm that the side which is getting the spark is in combustion mode ( both valves closed ). Again all guilty of this as well.

If all that checks out correctly then replace the plugs and kick a few times.
Check the plugs, if it did not fire they should be "wet" with petrol, if dry then check the carby.
If wet try new plugs, and/or  new plug leads.
One the subject of plug leads, they must be either solid copper wire or spiral wound and definately not low interfearence leads like on a car or modern motorcycle.
Should keep you busy for a day or two.
Bike Beesa
Trevor

Offline minibsa

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Re: BSA A7 ss
« Reply #14 on: 25.02. 2010 06:57 »
Just as a thought, have you checked that the pinion is tight on the magneto shaft? being a new pinion maybe it has slipped or is slipping on the taper. Probably not, but I have had it happen on an A7SS with similar results to your description
Cheers,   Bob.