BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: Wheelnut on 04 Jul, 2022, 18:19

Title: Ignition Choices for A65 Hornet
Post by: Wheelnut on 04 Jul, 2022, 18:19
My recently acquired 1966 A65 Hornet has Electrex World STK 012D self-generating ignition and I've come to the conclusion that this ignition system is not fit for purpose.

The issue is starting. It takes many kicks to start it, during which time it will either do nothing, or will kick back with such ferocity that a broken ankle will soon be a reality. Either that or a smashed up kneecap from my knee hitting the handlebar when it violently kicks back.

However, once started, it runs fine and ticks over nicely. The ignition timing has been checked and is spot on, and the carbs seem to be fine too.

The issue appears to be that the Electrex World STK 012D will only produce a spark from 300rpm. Anything less results in a very weak spark or none at all. Kicking it over hard with the plugs removed shows nothing more than a very weak yellow spark. Is it even possible to kick a 10.5:1 Hornet engine over at 300rpm?

So, with no desire for serious personal injury, I'm looking to fit an alternative system that actually works.

I'm thinking about converting to a battery 12V system, either with a Lucas alternator or total loss, and using VAPE, Pazon or Boyer electronic ignition. The bike doesn't have lights but will be used on the road.

Any recommendations?
Title: Re: Ignition Choices for A65 Hornet
Post by: Spaceman on 05 Jul, 2022, 06:29
One of the bikes I ride has a self-generating ignition system which is 35 years old and still produces a fat spark when you kick it over slowly. It sounds as though the ignition system fitted to your bike has a fault producing a weak spark and may also be forcing you to try to start the bike with the ignition too far advanced. The fault could well be with the CDI amplifier unit and it might therefore be worth trying to find a replacement unit if one can be obtained at a reasonable price.
Title: Re: Ignition Choices for A65 Hornet
Post by: tige on 05 Jul, 2022, 06:47
my A65 star has a pazon ignition fitted, It was on the bike when i purchased it, it works really well the bike always starts first or second kick, but i have fitted boyer to other bikes incl a 64 Bonneville and a tiger 90 quite recently, they also now start easy. However there are other reasons a spark can be weak, bad connections in the wires from A to B, crimped connectors especially the diy not factory crimped type. I always use none insulated ones and solder them and then use quality heat shrink, Bad coils leads and caps, personally i would check everything else first Check your earths are clean and tight also. Because a new ignition system will still need all these to be good to work correctly.
Title: Re: Ignition Choices for A65 Hornet
Post by: DAVE BRADY on 05 Jul, 2022, 11:35
Hi tige,

Boyer on A10 and A65 for many thousands of miles and reliable with good starting.  Another A65 with Pazon chosen for the greater degrees of advance giving a bit more retard for starting.  I think the latest Boyer have increased the amount of advance also.
No experience of Vape.


Dave.
Title: Re: Ignition Choices for A65 Hornet
Post by: Wheelnut on 06 Jul, 2022, 22:35
Thanks for the replies.

I'll do a few more checks before making any major changes. Some research on various forums indicates that some electronic ignition systems produce kick back symptoms depending on whether resistor type plugs and/or plug caps are employed. Seems strange, but worth investigating further. Just ordered some resistor type spark plugs to see if that helps.
Title: Re: Ignition Choices for A65 Hornet
Post by: pockets on 06 Jul, 2022, 23:25
I found that the A65   I've been working on was kicking back , have  serviced the carb and  when starting find that a few kicks over without ignition on with  choke fully on [which I didn't realize was with no tension in the e cable is when it is on]  and then switch  on ignition with choke still engaged and half throttle it fires after a few kicks . It tended to kick back when the throttle was closed .
Title: Re: Ignition Choices for A65 Hornet
Post by: Wheelnut on 25 Aug, 2022, 14:53
Decided to give up on the Electrex World batteryless system. Checked everything and still no improvement.  Fitted VAPE (distributed by Wassell) ignition with a battery and it works a treat. First or second kick starting and it never kicks back. Result!

Now that I know that it all works properly, the next step is to fit a Lucas type alternator and a reg/rec to provide a charging current for the battery.