SFC 1000 misfiring/popping/backfiring

Rob7 said:
Is the Ignitech a direct change out for the DMC?
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The short answer is yes, it can be. But only if you buy an Ignitech box that's compatible with the Laverda VR (magnetic) pickups. That way you're only up for the cost of the Ignitech ignition box. You'll need the 4-channel box for a 120? triple (around $300 I think).

Contact Red in Brisbane. He sells Ignitech systems in Australia. I'm not sure whether he stocks units suitable for use with the VR pickups, but I suspect he would as there would be other people in your situation. He will also set it up with a suitable program for your SFC 1000.

The long answer is ?  A technically better solution than to stick with the original pickups would be to buy Red's complete ignition system and alternator conversion. I'll cost significantly more but includes an upgraded 3-phase alternator and a new Hall-effect pickup board as well as the Ignitech ignition unit. So it'll get rid of any issues with the 40(ish) year old pickups and wiring.

At the risk of ruffling Red's feathers, but to be fair, I should also acknowledge that Greg Parrish sells Ignitech systems in Australia (for both Hall and VR pickups). I don't know whether he provides a full plug-and-play system, with Deutsch connectors for the pickup wiring like Red does.

Anyway, knowing Red's history with Ignitech way better than I know Greg's, I'd suggest Red as your first point of contact.





 
Not sure if Red has an upgrade for Series 2 engines for the alternator, but if you checked it is not the ignition key unit, all fuses are in place and in good shape, tightly mounted etc., Ignitech is a good alternative, yes. But be prepared that it comes unprogrammed and you will need a laptop to load the program on it I think. Red provides you everything you need to do that really, just making you aware it needs some work to be done. It is not a swap like unplug the DMC and re-connect the Ignitech, please.
 
Is the Ignitech a direct change out for the DMC?
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No, it's not.  On a 120 motor such as yours, the DMC uses an IR sensor mounted on an alloy plate in place of the 3 original Bosch triggers under the ignition cover. 

The Ignitech needs either a signal from the original triggers or something that replaces them, such as the Hall effect trigger board that Red can supply.  As Cam notes, the original triggers are VR (variable reluctor) type which work with the standard spec Ignitech box.  Note that if you decide to reuse the original Bosch triggers they do suffer from degrading insulation of the connecting wires (brittle). If you use Hall effect triggers, you need to buy a different spec Ignitech box to suit.

Depending who supplies it, the Ignitech box may need programming with a suitable ignition map which needs a laptop/PC with a serial port. USB adaptors don't work in my experience.


This is why I suggested replacing the DMC IR trigger for starters!! Cheap, reasonably quick and may well fix the problem 
 
Rob said:
No, it's not.  On a 120 motor such as yours, the DMC uses an IR sensor mounted on an alloy plate in place of the 3 original Bosch triggers under the ignition cover. 
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Ah, OK. I wasn't aware that the DMC on 120? motors used optical pickups.

In that case, an Ignitech unit built for Hall triggers should work. On their website, they say they supply the units for VR or Optical/Hall triggers.
 
Dellortoman said:
Ah, OK. I wasn't aware that the DMC on 120? motors used optical pickups.
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Only DMC II and later, the earlier DMC units utilised the original pick-ups.  These weren't very old and their shortcomings were not yet foreseen when the DMC first came on the market. 

piet
 
OK......an update.....positive for once (well sort of).....

Following some comment elsewhere on this forum stripped and cleaned the kill switch - found a small solder trace on one of the connecting wires - now removed. This didnt seem to make much difference other than the problem took longer to come into effect and wasnt as bad.

My tendency is to ride on front pilot light only and noted that when the issue arose the indicators started to speed up and flash quicker - am assuming this may be an over voltage issue once the battery has fully recharged? Voltage only reaching 14.4V so doenst seem excessive.  Anyhow, now started using main beam - and no further issues. I recall reference in another post to a widgit attached to the DMC unit to restrict voltage - maybe they are sensitive?

R7
 
Rob7 said:
I recall reference in another post to a widgit attached to the DMC unit to restrict voltage - maybe they are sensitive?
Click to expand...

That was probably me. I had a DMC that was sensitive to high voltage, but the upper voltage limit that it would tolerate gradually got lower as the thing got older. Switching the headlight on kept it going for a while, but it eventually got to the point that the headlight load wouldn't depress the system voltage enough. That was when I contacted Uwe Witt, and he sent me the 'widgit' (good name for it) to reduce the supply voltage to the  DMC unit, which kept the unit going for another year or so. Eventually the DMC's tolerance level dropped below the reduced level set by the widgit, so I threw the DMC in the bin and fitted an Ignitech ignition.

The 'widgit' from Uwe was enclosed inside a little epoxy-sealed box so I couldn't see what magical circuitry was inside it, but I suspect it was nothing more than a series resistor. I don't know what its value (in Ohms) would have been, but I could make an educated guess if you want to try adding a resistor to the 12V feed wire to your DMC unit. You can't do any harm by experimenting. If the series resistance is too low, it won't reduce the voltage enough to make any difference. If the resistance is too high, it'll just act like a kill switch and stop the unit working.

Start with a low resistance and work your way up. I'd suggest you start around 2-5 Ohms and see what happens. Choose a resistor that'll handle a couple of amps so it doesn't think it's a fuse!

Here's an idea: get two 5 Ohm resistors and connect them together in parallel to create a 2.5 Ohm array, and insert that into the feed wire to the DMC. If that doesn't reduce the voltage enough to fix the problem, take one of the resistors out (so you're left with a 5 Ohm resistance) and see if that works. If it's still not enough voltage drop, connect the two resistors in series to provide 10 Ohms. I'd be interested to know what happens.
 
FFS! If it's the DMC unit and Cam's on the money, bin it and either get a new DMC unit or go Ignitech - haven't heard of them displaying a voltage prob like this. It would drive me totally nuts.
 
Haven't had that either, maybe check the wires from the alternator to the regulator/rectifyer if there is a shorting. Or maybe some DPO has connected the 3rd phase directly to the other two (should go through the light switch and then to the regulator, as then it only is turned on when the light is on...).

I would also consider simply replacing the regulator with one that limits at 13,7v; best one that is adjustable, like Sachse is offering. That way, you could also use a LiFePo4 batterie, which is 8 kilo lighter than a gel or at least the same amount of kilos than a wett battery.
 
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