BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: shill on 14 March, 2017, 16:58:17

Title: BSA A10 Super Rocket rewire
Post by: shill on 14 March, 2017, 16:58:17
Hi, I have a 1958 Super Rocket. I took it to someone who was recommended by my local classic bike garage (they sadly only wanted to deal with Triumphs). Anyway I took it in because the mag needed reconditioning. Everything appeared to be fine, including the amp meter. I got him to do a few other bits as I didn't have much time. He told me he did a lot of rewiring, but I didn't think anything of it. I asked him to have a look at the light in the speedo as it didn't work.

Everything appeared to be fine, all lights were working. I was riding it home and I noticed the amp meter wasn't indicating charge only discharge. I have taken the seat off today and the negative lead is earthed which for a start I believe is wrong? Shouldn't it be positively earthed? I am not sure how this would change anything. Would that explain why that battery is only reading 4 volts and why It won't charge?

I can't understand what he's done or why the lights are not working. There are a couple of leads which have loose but none of the leads match the colours in the Haynes manual. Also some leads appear to be going to the wrong  switch terminals ect. My next question. In the Haynes manual there appears to be 7 terminals on the switch but there is only 6 on mine, so effectively the number (2) which is missing in the Haynes manual diagram. But this appears to be missing from other replicators I've seen on the market. So what is the correct way to wire up that switch? As in the Haynes manual you need to use the number 2 terminal which isn't there.

Please help,
Many thanks, Stephen.
Title: Re: BSA A10 Super Rocket rewire
Post by: JulianS on 14 March, 2017, 18:35:18
I would not want to take my bike to him.

The A10 wiring is quite simple, though the Haynes diagrams are not very helpful.

I have attached the diagram from the handbook for the 1960 on A10s but it would be the same for your bike. It could be that the wiring has been done with cable other than the original harness colours. You might find the wiring from headlight switch to light is blue/white for main beam and blue/red for dipped, as used on later bikes.

Spend time on the diagram and trace all the wires in your harness to satisfy yourself that its all connected up correctly.

The A10 from 1958 would originally have been positive earth though of course it could have been changed. If its been connected the wrong way around the voltage control unit may be damaged and  your dynamo may need to be repolarised for positive earth.

The light switch only needs 4 terminals, there should be a moulded in figure by each terminal to identify them. You need 2 3 4 and 5. 5 will have a connection between it and the central rotor. Depending on which switch you have its either internal and you wont see it (for a cowl type fitting) or an obvious external one ( for seperate headlamp fitting)
Title: Re: BSA A10 Super Rocket rewire
Post by: Bess on 14 March, 2017, 18:57:23
Hi Shill,
Connect number 2 to number 5. Number 2 supplies the dip switch onto headlight, number 5 tail light and speedo so using 5 will not be a problem.

Here's a neg earth diagram if you need it (there's 2 but they are both the same).

Best wishes...
Title: Re: BSA A10 Super Rocket rewire
Post by: JulianS on 14 March, 2017, 20:00:31
Connect 2 to 5, then given the internal or external  connection between 5 and central rotor the headlight and pilot will come on in the pilot light position

Off position switch rotor connects 5 to 4

Pilot position switch rotor connects 4 to 3. for pilot/tail speedo

Headlight position switch rotor connects 3 to 2 for headlight and the internal connection feeds to the tail and speedo bulb (but not the pilot)
Title: Re: BSA A10 Super Rocket rewire
Post by: SLIPPERY SAM on 16 March, 2017, 13:53:50
Stephen, just be careful as you go.  If you've been riding about with things working it should be a case of tracking down the culprit and not pulling stuff off and introducing more variables.
On your earth polarity - I'm new to the A10 but consider myself handy with electrics - I re-wired my machine and boy is it confusing. Red's to black, black to purple, brown to +'ve and fuse to frame - man it is impossible to work out from a glance and can easily get you mixed up unless you trace things through logically.  Thankfully it's a small harness and it is possible to step through the logic.  My tip would be don't assume anything from the colour of the wire - follow the complete circuit through from one side of the battery all the way back to the other.
Also - note - and again being inexperienced I found a lot of this out on the forum with the help of the very knowledagable members - the lighting and power wiring is virtually independant of the charging - ie the lighting and such should work fine without the bike running - and the charging should simply charge the battery.  Two separate tests.  that said - you do need the polarities lined up.  Search on the forums - there should be a few tests and pointers for you.
Good luck  Raymond.
Title: Re: BSA A10 Super Rocket rewire
Post by: bobandbec on 17 March, 2017, 22:54:14
I had a problem with my '62 A65 electrics which I tried to fix by tracing faults. Never actually got to the bottom of it. Just got fed up of breaking down.
Bought a new complete loom from a person on E bay who makes bike looms up and labels all wires ready to go on the bike.
I found it much easier to rip all of the old wires out and start from scratch.
Title: Re: BSA A10 Super Rocket rewire
Post by: STAR TWIN on 18 March, 2017, 06:56:41
Your A10 should be positive earth. The first check is to be sure the dynamo is working and correct polarity. Remove the F and D dynamo leads. Make up a jumper wire and connect the dynamo F and D terminals together. Connect one terminal of a voltmeter to the jumper wire and the other to earth. Start your bike. You should get a reading on your voltmeter on a fast tickover - up to 26 volts if you rev it (not recommended). You should then deduce the polarity of your dynamo.
If it's positive, your shop has made an arse of your wiring and you should start by reversing your battery leads. If it's negative they've at least got that bit right.