SF2 Voltage Regulater?

M

mtnduc

Junior member
Got the SF2 running but my generator wasn't.
Sooo .... had that rebuiilt and now it generates but, nothing is coming through the aftermarket voltage regulator my builder installed to charge the battery.
Is there a type/brand you recommend for the SF2 with a DMC ignition?

TIA.

Brian
 
I believe my builder said it is off of a Honda 150 with a two position >4Amp or <4Amp position.

As for wiring ... no idea.
I assume +/- in +/- out. 

I know switching the output wires on the gen had no effect on current to the battery though.
 
We covered this on the Laverdapedia site a while ago. From experience the DC generator on the SF can only run with the standard type regulator with the vibrating contacts. Cars with the same type genny used that type of regulator also. I wanted to use electronic regulator but all auto electricians said there were none to suit a DC generator. I had used replacement regulators from VW but they burnt out the overcharge resistor when touring all day at 6000rpm as we used to in Oz. I went back to original Lav item but charging was borderline. I had auto electricians "set" them up for me but it never helped. I was recommended a place that specialised in marine electrics and he said he needed the generator itself to adjust the reg up to. It has charged perfectly since then 15 yrs ago. The generator tested at 22amps (the same as the identical looking VW genny), he said it was rated at 11amps due to lack of cooling slots. I don't know if your Honda 150 regulator is suitable. I know of no Honda with a DC generator. Modern bike shops are unlikely to have any relevant experience. Ring around to auto electricians with knowledge and experience with this type of system. It is an extremely simple old system which is ample for the bike. When it is tested and set up on a bench you will know if the problem lies another place in the bikes wiring (the wire to the charge light earthing out for example). I had been looking seriously of going the alternator route when I fortunately stumbled on this guy who knew the system.
Your ignition has nothing to do with the charging system other than it needs power from the battery.
Make sure when you get it together that the regulator is properly rubber mounted and all the wires and contacts to the battery, genny, regulator and frame are good. 
 
Tippie -- Thanks.
On the recommendation of a friend of mine who has over 100 older motorcycles, mostly Italian, I purchased a Bosch VR from a 1968 12V VW.
Yesterday properly installed it per the Green book wiring diagram and still I get no voltage increase over approx 12.45v at idle when applying increased rpms measuring at the battery.
DF to DF
D+ to D+
D- to ground on VR (mounting tab)
Power to switch/starter/battery

I'm not using any gauges so the VR output to dash light is simply dual wired to the Power to switch/starter/battery line.

Today I'm going to go back and verify my ground is solid to the frame.

As well, I think I'll ring the shop who rebuilt/cleaned my Generator to see about this matching you describe.  However I don't see any place to make any adjustments on the VR to set/match it to the stock Bosch Generator.
 
Brian - just a thought from my old car days.  New (or service replacement) dynamos needed to be polarized to get 'em to work.  Reason is that they rely on residual magnetism in the field winding poles to self-excite (steady, boy!  :D )  After  a rebuild the weak residual magnetism can be lost, so you need to 'flash' (god, this gets worse) the field winding with battery voltage. 

One thing to watch - the Bosch dynamo on a Laverda has its field winding terminal connected to earth.  So I think this means you need to flash the D+ terminal with +12v from the battery with the DF terminal connected to battery -12v.  DO THIS WITH THE DYNAMO DISCONNECTED from everything else!

If you're interested in finding out a bit more on Laverda Bosch dynamo field windings, Volker Sachse's website http://www.elektronik-sachse.de/index_en.htmmay help - click on Regulator 5a and then read about his little test!

Finally,  I don't think you should connect the warning light feed from the VR to the +12v line - leave it disconnected at the VR if you have no warning light.
 
It sounds like you are getting somewhere.
Interesting info Brad.
From memory the charge light in the dash has power to the light and it earths through the regulator. If that's correct then the wire from the regulator is not a feed but provides the earth for the lamp. I encountered a bike with the terminal in the dash touching the chrome trim causing it to not charge.
If you have no globe in that circuit then leave the wire off the regulator as Brad suggests.
 
Thanks Brad.
I'd heard about this flashing concept from a friend as well.
How do you do this flashing?
Connect the terminals as suggested for 30 seconds, 1 minute, 5 minutes, longer?  Do I turn the key to the on position, hit the starter?

Sorry this is new to me.

Thanks again.

Note:  The charge light spade is empty/disconnected on the VR.
 
Brian - sorry - to clarify. 

Flashing means just that - briefly flick the D+ connection with +12volts from the battery whilst the D- is connected to battery negative.  There will be a splash of arcing as the current flows through the dynamo field winding.  There is no benefit in holding the connection on for more than a second or two.  For safety, please do this with the dynamo and battery completely removed from the bike! (You may find the armature tries to move, so drive belt should be removed.) 

At a pinch, you could do in situ with the belt slackened & battery & dynamo fully disconnected from bike wiring.  Use two lengths of wire from battery + and -.  Be very careful not to short the battery out  :o
 
I recall flashing my 750 SFC regulator when I rebuilt my charging system. D+ to B+ with a piece of 14 guage wire. I just touched these terminals on the regulator briefly...1 or 2 seconds with everything installed on the bike as it should be, key off, bike not running.  Never any theatrics or sparks.  This was common practice for these setups, for cars and bikes. I guess with age it becomes a distant memory for those of us who did it and an unknown practice in modern times. Now if you have already run the bike with out doing this first you may have already screwed up the regulator.....I recall doing this as well.  :D :D See if it is charging at around 14v, at above idle speed, at 3000 or 4000RPMs or so. I if not see if the regulator points are welded together. If so unbreak  them and clean them up by filing smooth. Then flash it. If that does not work the regulator may be shot now. There may be a way to test the regulator to be certain (I don't recall) or try another one. 
 
Thanks to all.
Flashed the Gen and all is good, nice charge going to the battery!
Plus, I learned something for future reference.
 
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