The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: Gonemad on 23.09. 2011 10:33

Title: K-Tek constant voltage control
Post by: Gonemad on 23.09. 2011 10:33
Let me begin by stating that anything with a wire on it has me beaten before I begin.  Mechanical things, yes.  Electrical things, no.
So, starting with that as an understanding... I have a K-Tek constant voltage regulator on my BSA RGS, Super Rocket based, replica.  Somebody that is even more silly than me put a new battery on the bike, the wrong way around, i.e. negative earth.  That ruined the battery in that it would not accept a charge again.  Another new battery was purchased and installed by the same bloke, again the wrong way around.  I spotted the error after a very short time and the battery seems, so far, to have recovered after charging.
I have been advised that the K-Tek unit is guaranteed fried.
So, after all that... the point of this.  There is a notable supplier who states on his website that he will not sell the K-Tek unit because he thinks that they are rubbish and he is fed up with changing them out. 
The question then: Are they any good, or is there a recognised better product that even a dummy like me could wire in place? Question two: Is there any possibility that I might also have a reversed polarity Dynamo now and should I check this before wiring in a new Voltage Control Regulator? 
Title: Re: K-Tek constant voltage control
Post by: Topdad on 23.09. 2011 12:35
Hi gonemad,( and haven't we all with these BSA's )  I also am not the most happy bunny when messing about with electrical bits but with a bit of patience and help you find that these things are quite........ basic. I bought my "magic box" from Sean hawker at ,as was CMES now hawker electrical , ,8 yrs ago and still working fine ,wiring details on the side of unit,very strightforward. The guy is a BSAOC member and gives members a discount and every thing He sells as been tested by himself on a B33 which has covered an enourmous mileage. They are £45 but work.he also did my dynamo and I've just bought a belt drive kit from him.
Re the dynamo shouldn't make any difference to this unit has it can be connected + or - earth ,or so it says ,however, changing the polarity has been covered in a few posts recently can't remember the details but i'm sure more electrical connected guys here can explain it again.
On further point I'd not let your friend who obviously hates battery's to touch anything electrical again ,could save you money!! Best wishes BobH.
Title: Re: K-Tek constant voltage control
Post by: Triton Thrasher on 23.09. 2011 12:50
I used a K-tec for a few years and it worked, but I shorted something and busted it.

I think the Manortec, now called DVR something, is the dynamo regulator of choice nowadays.  Most of the other types seem to have the stupid characteristic of draining the battery at low revs.
Title: Re: K-Tek constant voltage control
Post by: Dynamo Regulators Mike on 23.09. 2011 13:02
Hi Gonemad,
I would say there is a fair chance that reverse connected K-Tec unit will have powered your field the other polarity. Just touch the field wire  to the battery live of the desired polarity and it is now confirmed as the correct polarity.
There are a number of electronic regulators units on the market. As far as I know the DVR2 from Dynamo Regulators Ltd ( is the most robust unit on the market today. Fitted with a fuse as instructions (and as is wise protection in any event) it survives reverse connection; the fuse blows, a cheaper option.
It is supplied by an active board member and BSA club member, that is my company, DRL. The DVR2 has been used extensively on my own A10 (along with our high quality timing belt drive, also discussed on this forum. BTW I do wonder how the hawker belt drive kit was tested on a  single, high mileage or not, but that is neither here nor there.) There are many other users on this forum
DVR2 is in stock for quick dispatch, simple on-line payment and decent back up if required. Just select positive or negative earth. No electronic unit does both. 6 or 12 V selectable. Price £44 including first class postage in UK.
My apologies if anyone is offended by the commercial content in direct response to a question.
Best Regards
M Hutchings, Director, DRL
Title: Re: K-Tek constant voltage control
Post by: RichardL on 23.09. 2011 13:32
Well, before Mike's post, I wanted to jump in and recommend the DVR2 as being the regulator that I and many others here successfully and happily use. But, knowing nothing of the K-tek or the other possible substitutes, I didn't want to talk out of my hat. So, now, I am comfortable in saying that you,  too,  are likely to happy with a DVR2. For, me, no more fried batteries and very little headlight variation with throttle.

Richard L.

Edit: Some here are still quite successful with relay-based regulators,  but I could never get it set right and, perhaps I should be embarrased to say,  my education is electrical engineering.

Title: Re: K-Tek constant voltage control
Post by: groily on 23.09. 2011 15:16
I've never had any hesitation in recommending DVR2s because I find them excellent. Mike is very modest in what he says. I have three (which is nothing compared to some members on here) but not a moment's hassle in a lot of miles, quite a few of them in the dark and wet. 2 at 12v, one still at 6v.
Title: Re: K-Tek constant voltage control
Post by: Gonemad on 23.09. 2011 17:35
Thank you all Gentlemen.  There are some things that I am good at and there are some things that I am not, so that information was just what I needed and I am happy to take the advice of those with experience. I will take direct contact with Mike Hutchins and place my order.
I should explain that I have just bought this bike from a chum in Norway, who had the bike in England and is just about to retire to Spain.  His son put the batteries in.....  The bike is fully rebuilt to a high standard but, will not start.  This may well be due to the thing having been standing, well stored, for about eight years.  I should also explain that Gonemad was the response from a chum who found out what I had paid for an original, very near mint, RGS Owners Handbook on E-Bay.              ?Angus, y?r gone mad.?
Thanks again lads.
Title: Re: K-Tek constant voltage control
Post by: Gonemad on 28.09. 2011 20:15
Having now fixed the kick start return spring I can now focus on the electrical issues with the bike and why there is no spark, at all, at either plug. 
My new voltage control regulator, from Dynamo Regulators - see Mike Hutchins post below, arrived in the post today and I have to say that it does look a very smart bit of kit.
Before I install it think that I will have to 'flash' the dynamo to ensure that it is still positive earth.  I think that this is done by taking a wire from the F side of the dynamo to the positive side of the battery, which I assume has to be properly connected.  I also think that if the polarity has been reversed, flashing will set the thing right while if the polarity has not been reversed flashing will make no difference to the dynamo, which will stay right.  Have I got that right?  Once I am certain that I have the dynamo polarity correct, couldn't use the word right again, I will then fit the shiny new voltage control regulator.
After that..... I will clean the points at the magneto.... and it will start.
Have I got that right........?
I am starting to feel a certain cheque book engineering coming on here....
Title: Re: K-Tek constant voltage control
Post by: muskrat on 28.09. 2011 21:06
G'day Angus,
                  NO, flash to the ACTIVE side of the battery. - for + earth or + for - earth. In your case flash it to -.
Title: Re: K-Tek constant voltage control
Post by: Gonemad on 28.09. 2011 22:36
Whoops, that was close as I will be looking at the bike again on Saturday.  Thank you Muskrat.

So then, to begin again... a wire then from the F terminal, whatever that is, to the -ve side of the battery.

Is that right?

Have I also understood it correctly that if the dynamo has not suffered reversed polarity by the installation of the battery the wrong way around, but is as it should be, then flashing it will make no difference?  I wouldn't want to reverse the polarity of a perfectly good dynamo.

Title: Re: K-Tek constant voltage control
Post by: Dynamo Regulators Mike on 29.09. 2011 16:45

To confirm:
To flash the dynamo magnetic field to ensure the correct polarity from it connect a wire from the 'F' or field terminal of the dynamo to the negative of the battery for a second. That is all it takes. The wire to the this Field terminal is usually green. (The other dynamo wire, the Output, terminal 'D' is usually yellow in the Lucas convention. This wire should go to the dynamo brush opposite to the earthed one.) The positive of the battery connected to earth, that is the frame here. The dynamo case is also earthed via the engine.

There is no danger of changing the polarity the wrong way, and you can do it as many times as you wish with no fear of bad consequences.

Thanks for the complements about the DVR2 to all.

Title: Re: K-Tek constant voltage control
Post by: Gonemad on 03.10. 2011 19:36
On Saturday, with the assistance of a chum, we found that the contact between the plug caps and the HT leads was non-existent, thus no spark at the plugs.  A little bit of reworking and a spark was achieved.  Following a failure to get fuel to the carburettor, solved by a light tapping of the carburettor with a block of wood and... to my great amazement, the thing started.
As we were inside the garage my neighbours are now aware that I have a motorbike.
The engine revved far too quickly and on the second attempt revved even more quickly leaving the rev counter stuck at about 2000rpm, even with the cable removed to try to reset it. The cable looks a bit crude with the wires pressed together to form a square male for the rev counter.  Is it really that crude?
I may well take the carburetor off and clean it properly as the bike has stood for some years and may be gummed up with dry petrol.

I have now got the wire use for / colour code of the old K-Tec unit and know what the wires on the new Dynamo Regulators voltage control unit do so tomorrow I will install that together with a new LT wire as the old one looked slightly past it.
I took a wire from the F point on the Dynamo and touched it to the Negative side of the battery (6V + earth bike) and did not see any kind of spark, as I might have expected, so I suppose that all is well there.

Many thanks Mike Hutchins and Muskrat.

Title: Re: K-Tek constant voltage control
Post by: Triton Thrasher on 04.10. 2011 12:02
If the cable stops turning suddenly, a chronometric speedo or tacho stays at its last reading.

Rotate the cable or the bit it fits into, slowly and the needle will drop back to 0.
Title: Re: K-Tek constant voltage control
Post by: Gonemad on 04.10. 2011 17:20
Well... that's another thing I didn't know.
It's pretty likely that my bike will stop 'suddenly' as I have an ignition switch built in to a secret place underneath the saddle on the right hand side. I stopped the engine, from the high rev's, by simply switching it off.  My expensive E-Bay BSA Instruction Manual does not tell me how to stop the engine and I cannot remember how I used to stop my Shooting Star some fifty years ago.  The only way that I can think of, considering that the ignition switch is not standard, would be to turn of the fuel tap and let the bike run out of petrol.  That would have the minor advantage of letting the mixture run lean at the death which would burn the plugs clean.  It would also let the engine stop slowly perhaps avoiding the rev counter stopping with a reading remaining.
I did manage to fiddle the thing back to about zero last evening with a matchstick.
Thanks for the reply Triton Thrasher.
Title: Re: K-Tek constant voltage control
Post by: RichardL on 04.10. 2011 18:33

Under normal shut-off or braking, I don't think you can lose revs or speed fast enough to keep the tach and speedo from updating,  which occurs about every 3/4 second.

Normally, the engine is killed by grounding the engine-stop connection coming out of the points cap cover at the back of the magneto.  A wire from this connection connects to a button on your handlebars, which grounds the wire to said handlebars. This is a good thing to have so you can shut off without fumbling for the security switch.  

By the way, your secret shut-off switch is no longer a secret.

Richard L.
Title: Re: K-Tek constant voltage control
Post by: Gonemad on 05.10. 2011 16:48
Darn it Richard.  Would that be the ignition switch built in to a secret place underneath the saddle on the right hand side?  How on earth did you find out?
Actualy, it was a play on a well known line from a TV comedy program here in Blighty called Dad's Army.  With a setting during the second world war a group of German soldiers had captured a squad of British Home Guard soldiers.  One of the young British soldiers has the family name, Pike. When the German soldiers begin asking questions the commanding British officer says, "Don't tell 'em your name Pike."
Everbody here knows the line and it often gets missused, as with my secret switch location.

I remember the kill switch to which you refer now.  I had it on my 1955 Shooting Star all those years ago.  My 'new' bike does not have one, probably removed during the restoration by the PO, but it does have the secret ignition switch which is wired into the same line. When the bike was first started, after all those years of standing, it raced at high revs and when I stopped it, with the ignition - kill switch, it stopped very quickly leaving the rev counter at a high reading.  I now know that this is not a problem.  I also took the tank off today with the intention of removing the carburetor for thorough cleaning in case it was gummed up with old dry petrol.  However, with the tank removed the throttle cable did what it was supposed to do so I am assuming that it must have been trapped by the tank against the frame.  I will put the tank back tomorrow, with the cable tied to the frame of course, and see what happens when I start it again.

Thanks for the input again lads.  I think that I am getting on top of this bike now.

Title: Re: K-Tek constant voltage control
Post by: Topdad on 06.10. 2011 12:22
Good afternoon Angus, whilst you've got the tank off ,even if you've got the tank rubbers fitted in there bracket there can still be alot of vibration,I use  22mmpipe insulation ,you know the formed preslit stuff and tape it over theftop frame tube and  cables( once they are secure and moving easily) cut it clear of the central bolt hole and it keeps it lovely and snug and a lot less vibes for a very few pence.
By the way I think your secrets safe with Richard and everyone on this site ,just check he hasn't booked a visit to Norfolk yet !
Title: Re: K-Tek constant voltage control
Post by: Gonemad on 06.10. 2011 16:36
Hello Bob.
That's a good tip that I shall follow.  There was some insulation along the top of the top frame member but certainly not as thick as the insulation that you use.

Today I got the bike to start again, and it even had a good slow tick over this time so it was the trapped throttle cable after all. I then rode it for the first time, around a local and empty private car park. Quite fantastic. A little wobbly - uncertain - at the front wheel on right hand turns but that well be the tyre, ribbed, at least 12 years old and pretty worn. Although the rear tyre looks very good I will throw away both tyres, as they are both at least 12 years old, and get new tubes and tyres next spring.

I have to say that I am pretty chuffed to have joined this site.  Quite wonderful the way that so many are prepared to share their knowledge.  My time will come, there must be somebody that knows less than me about these bikes....

I think that I should move my secret switch now to a new hiding place on the right hand side of the handlebars.

Title: Re: K-Tek constant voltage control
Post by: A10Boy on 07.10. 2011 14:15
Where to??
Title: Re: K-Tek constant voltage control
Post by: RichardL on 07.10. 2011 15:33
So, if I have this right: O'Hare to Heathrow; Heathrow Express to Paddington Station; Circle to Liverpool Street; National Express to Norwich; ask where Angus with the old BSA lives, and Bob's your uncle!

So, have you met Andy at Leigh Classics in Leigh-On-Sea? If not, you should try to get there, if for no other reason than telling him that Richard from Chicago says "Hello".

I see you are not too far from Bury St. Edmunds. I worked on the audio design there for the civic hall in the Cattle Market project. However, it was by long distance and I have not actually been there.

Richard L.

Title: Re: K-Tek constant voltage control
Post by: Gonemad on 10.10. 2011 17:56
Next time I am passing through Leigh - on - Sea I will pass on your regards for sure Richard.

My Uncle Bob sends his greetings.