BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: paulski on 22 October, 2021, 23:52:11

Title: strobe timing
Post by: paulski on 22 October, 2021, 23:52:11
hello folks, any tips appreciated on how to strobe my bsa a10 1959 golden flash.  I've fitted a thorspark ignition and fitted a srm timing disc to the front sprocket . its still on 6v . statically set it runs well but really is guesswork so would like to strobe it, but can't get  my gun flashing steady, tried 2 guns one a snap-on. is it because of the 6v system and 12v gun? ,, gun hooked up on a 12v battery pack .??? and tried pick up on both leads the same?? sure I'm missing something simple?
Title: Re: strobe timing
Post by: corneg2 on 23 October, 2021, 09:59:23
Hello paulski, I used a strobe no probs on my A10. I did convert to 12v though. Take a look at the strobe gun itself. Mine has a slide adjuster on it for different rev ranges. Could be yours in just set for the wrong rev range. Also check you have a good connection to the HT lead and spark plug. Alternatively, if she runs well just on mechanical timing then you could mark the current position on the fine adjust and tweak a little at a time. You only need to move it 1 degree to get two degrees of timing adjustment at the crank - at least that's what mine does. And to get final timing mine only needed the smallest of fine adjustment from the mechanical timed point - if that makes sense.
Title: Re: strobe timing
Post by: paulski on 24 October, 2021, 22:53:57
cheers buddy, it seems spot on running although does pop if i rev it hard and fast from idle?  wonder if thats too much advance or retard on timing? also noticed i had to turn ticke over down a fair bit once it got hot it raised.? brand new carb on it. need to get some miles on it and tweek as i go i think but any advise is appreciated , all new to me these old britbikes lol

Title: Re: strobe timing
Post by: DAVE BRADY on 25 October, 2021, 08:44:16
Hi Paulski,

The popping on quick throttle opening could be a slightly weak mixture on the idle/primary settings.  Is the carb set up as standard and is there an air filter and choke fitted?  The tick over is usually best set when the engine is warm.  If you have statically set the timing accurately with a disc and the bike runs well then using a strobe will make little difference unless you are going to be running at very high revs.   Is the engine a new rebuild or already run in?

Title: Re: strobe timing
Post by: paulski on 25 October, 2021, 22:25:49
hi Dave , I've recently bought it as a fully restored bike been sat for 15 years , so not sure of engine work done but engine is spotless with repainted barrels etc, sounds sweet so presume its been gone through back then. speedo is fully rebuilt with receipts to prove and it shows just 500miles so i presume engine  was run in somewhat back then,, carb is new from surrey cycles all set up ready to fit, maybe i will try bigger pilot jet and see if it improves. or maybe one notch on the needle setting.? at present stripping out the primary side to sort out the gearbox output seal thats pissin out, then i will have a play with carb, cheers bud
Title: Re: strobe timing
Post by: paulski on 25 October, 2021, 22:27:29
yes has air filter pan type and choke is the extra carb slide type
Title: Re: strobe timing
Post by: DAVE BRADY on 26 October, 2021, 08:12:57

I use a 'Colortune' to help set the carb up.  If you do not know what it is, it has a glass spark plug that allows the colour of the combustion to be seen as the engine is running.  The mixture can be adjusted and the result observed in real time.  It could be that the pilot screw needs tweaking a bit.  A chart gives the combustion colour to aim for and this can help with the full rev range.


Title: Re: strobe timing
Post by: paulski on 03 November, 2021, 07:22:20
will have a look at that idea, sounds cool. cheers