Thought it was OK- WITT- but it ain't.

  • Thread starter Thread starter Reggie3cl
  • Start date Start date
Funny thing is I used to drive around in an Austin 1100 that was my grandfather's car at one time...
 
Reggie,

The DMC II will be ok with currents between 6 and 16 volts.  Under 6, current is insufficient, over 16, the unit shuts down to protect itself.

Voltage drop of more than 3-4V while cranking points to excessive drain through starter motor or shagged battery.  Should still start up ok, but might be worthwhile to measure current at the DMC supply, ie, behind killl switch, etc.  Might be drastically lower...

Rip the sucker out the Beemer and give that a try!

piet
 
Should still start up ok, but might be worthwhile to measure current at the DMC supply, ie, behind killl switch, etc.  Might be drastically lower...
Click to expand...

Well I checked the voltage coming through the red wire at the terminal on the Witt and it seemed fine.  Am going to bypass the ignition switch and kill switch and see if that changes anything.
 
When I swapped out my blue box DMC recently for a sasche I noticed the wires going into where the pickups are were very exposed. The insulation was all hard and mostly cracked off. Red reckons this is a common problem. Symptoms for me was when it was warmed up it would start missing badly between about 1200 to 2500 rpm. I have no doubt the vibes in that range were causing the wires to short to earth and cause the missing.

No doubt replacing these wires would have solved the problem, but the new sasche feels so much better across all revs so I will just leave it in there.

So might be worth checking the pickup wires on yours.

 
95% of all times a bike with a Witt makes trouble it is either the battery (which might read nice 13.5V in idle but after r?ding a while, the voltage dropps f.e. around 4.000 revs and the bike sputters and dies sometimes even), or - as pointed also out already - the pickup wires. Check for cracks in the insulation, I bet you'll find some...
 
?? If you have Pickups still, they are at least 25 years old... just to make sure: I mean the wires from the pickups in the engine to the plug where you connect them to the DMC... Bosch engine? if so, pull the alternator and look at the pickup-cables on the pickup plate. They tend to have the insulation cut through where they go through the pickup plate. similar effect on the bike of a friend of mine, his wires looked good up to this point. once replace, the bike ran perfectly...
 
Hi Reggie
Glad that helped.The trouble is that with switches and wiring connections,voltage does not always tell the whole story,you really need to measure the voltages under load,you could now bridge out the ignition switch and kill switch independently to eliminate each one of those in turn and the connections to them.pain staking but if you are methodical you WILL find your problem
Neale
 
And yet, no.  It may have been a suspect power feed, or whatever, but all working now, kill switch or not.  Bollocks to it, if it won't start I know what to do- time to chuck it all back together.
 
Managed to replicate the problem even with the direct feed.  All connections are good.

Basically if I leave the ignition switched off for a while (the time taken to come inside and grab a beer and go back to the shed, for example) then it will not start firing on the test setting until it's been on about 20 seconds.  Once it's firing you can switch off and on as many times with the ignition or kill switches as you like and it fires.

Has to be a box problem- the wiring is simple and OK.  Pretty odd, guess I'll just have to leave it to 'charge up' before hitting the button.  :o :D
 
I'm sure Keith would lend me one, but as long as I know how to get it started, I'll live with it for now and maybe send it back for testing at the end of the season. 
 
I had this problem with a Jag XJ12 which had a reconditioned ECU. Started ok drove a few hundred yards and stopped. After a period of time it started again and went ok for the rest of the journey. I replaced everything on that car that I could think of. In the end I found it was the ECU. OK not exactly the same thing but definately an electronic maladie.
 
I had a Piranha ignition on my 750/4 for 18 years without problem. Then the bike behaved erratically, misfiring occasionally, hard to start and so on. I persevered with it until it left me stranded at the roadside miles from anywhere.
It was the black box. New replacement totally solved all issues.
My point is that I knew it was faulty yet kept using it, thinking I could always nurse it home, until...
 
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