Tuning Moto Witt EMS

L

LaverdaDave

New member
Location
Toowoomba, Australia
My '76 750SF if fitted with aftermarket Moto Witt EMS.  The gremlins got in and loosened the screws that hold the 'grundplatte' in place so the timing got out.  I finally realised the problem and have got it running by adjusting the grundplatte to a position that seems to have the engine running smoothly.  The documentation suggests the timing can be checked with a strobeoscope; but how does one use a strobe on this type of ignition.  The grundplatte does not move!!.  An additional issue is that she often fails to spark on first try.  It is necessary to place it in gear and rock it a little until it will start.  I am assuming this is an indication that the timing is not correct and the EMS will not spark when the cylinder is too far from the correct position.

Any help on how to check and correct the timing with this system would be greatly appreciated.
 
Dave,

On the RH end of the crank you will find the dynamo pulley and starter clutch.  On the clutch housing you should find the timing marks necessary to time the ignition.  "PM" denotes "punto maggiore" or TDC, "A" = "accensione" or ignition.  The corresponding marking on the engine case is at approx 1 o'clock of the starter clutch.

You should first ascertain that curve 1 is selected in the box.  If it is a blue coloured box, DMC I, all the dip switches need to be in the "off" position.  If bronze coloured, DMC II, the rotating switch needs to be set on "1".  These switches are located in a recess on the side of the box to which the rubber mounts are fitted and is closed by a black plastic bung.  The engine can be started and the timing of either cylinder checked with a strobe light on the starter clutch housing.
With the engine running at approx 3500rpm, the "A" marking should line up with the case marking.  Adjust the ignition base plate (grundplatte) accordingly.

LaverdaDave said:
An additional issue is that she often fails to spark on first try.  It is necessary to place it in gear and rock it a little until it will start.  
Click to expand...

??  

Not sure I understand what you're trying to say...

Does the starter turn the engine and the engine won't start?  Or does the starter fail to spin the engine, which sounds more likely.  In this case, the carbon brushes in the starter motor are likely to be worn or the starter is completely knackered (highly unlikely!)

HTH,
piet

Oh, yes, welcome to best place in the universe for Laverda nutters!
 
No response at all when I press the starter button.  Rock the bike in gear a little to move the cylinder over a little and it starts first time as expected.  It is either no response or goes perfectly.
 
Either the starter is jamming/failing to spin or there's a slim chance the starter solenoid/relay is jamming/not connecting and the rocking motion is enough to free it off.  Has nothing to do with the ignition, different issue!

piet
 
sfcpiet said:
You should first ascertain that curve 1 is selected in the box.  If it is a blue coloured box, DMC I, all the dip switches need to be in the "off" position.  
Click to expand...

IMG_2550.jpg


Is this the blue box type you refer to? I've tried to get some set up instructions from Uwe Witt but so far have just established that it was made in 1989. My bike is running fine but i'd like the information for the day it stops working.

Anybody got a copy of the instructions they could email to me?

Thanks,

Stuart
 
gibbo-123 said:
Is this the blue box type you refer to? I've tried to get some set up instructions from Uwe Witt but so far have just established that it was made in 1989. My bike is running fine but i'd like the information for the day it stops working.
Click to expand...

Yes, Stuart.

Why should it?  Lots of those still doing sterling service world-wide.  Basically, all that needs to be done is to ensure the wiring is in good shape and remains so, most faults that crop up are related to bad connections due to shoddy workmanship on the part of the installer or corrosion that sets in after a few years.

I could scan you my copy of installation/user manual, but that is in german only.  All that would be of use would be the dip switch settings and the appropriate ignition curve selection.

piet
 
Piet/Rob,

Think i've found what I was looking for on the ILOC website. No wiring diagram for the 750 though, will have to work it out from my bike.

Regarding the different dip switch settings, why so many advance curves? I've never had the choice on my Triumph Bonneville. Which is the best curve for a standard bike?, I can then compare with how my bike is set.

Thanks chaps,

Stuart
 
Stuart,

Many Laverdas have seen several modifications/upgrades in their life.  Even lots of deviations from anything resembling stock.  To make life easier for the backyard bodger owner/tuner, Moto Witt opted to include several different ignition curves to cope with different engine specs. 

Perhaps one reason why Laverdas hold together and tuned brit twins usually don't! :D

Stock engine = curve #1

piet
 
sfcpiet said:
Perhaps one reason why Laverdas hold together and tuned brit twins usually don't! :D

piet
Click to expand...

Thanks for the info Piet,

My 750 Bonneville was running so well last Summer I exploited it to the full and broke the gearbox!. Next bike on the ramp for fixing although I've lost a bit of interest since i entered the world of Laverda.

Stuart
 
sfcpiet said:
Why should it? (stop - DMC 1)
Click to expand...

Mine does - quite often, and has to be re-booted by powering off then on again. It's also very sensitive to supply voltage - the max voltage it will tolerate is gradually decreasing, presumably as some internal component degenerates (may be related to the spontaneous stopping issue - I dunno). It's already below normal battery voltage so I have to use a 10V supply. Its dummy-spits are becoming more frequent and sometimes I have to power cycle it 2 or 3 times to get it to work again, so it's giving me the shits enough to chuck it in the bin.

I contacted Uwe about it a couple of years ago. He was helpful with controlling the supply voltage (sent me the 10V limiter), but said it will probably die altogether sooner or later. I really should replace it before I get stranded on a rainy night in the middle of nowhere.

Cheers,
Cam
 
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