Witt - Optical

Simonr501

Simonr501

Hero member
Location
Lympne, Kent. UK
I thought I would pass on some 'learning' regarding the Witt DMC2 optical trigger (fitted to series II triples only apparently).

I had a problem with the Jota 120. When the engine was good and hot the engine seemed to peter out and stop (I thought I was out of fuel), which progressed to cutting out as if the kill switch had been flicked.
I was stranded by the side of the road, but after a rest the engine would run for a while.

I tried all sorts of things, including pulling at the wiring with the Witt in test mode (0) and the plugs resting on the cam cover sparking away nicely. I didn't identify any loose connections, bad wiring or anything suspicious. The sparks stopped when putting a card in front of the lens - so everything normal.

However, it seems the culprit was the optical trigger! (thanks for the suggestions and help from Keith N and Reggie).
I cleaned the lens with a (carefully squashed) cotton bud and no failure after a few hours today.

It seems the optical sensors do not perform so well at high temperature, some units never ever fail and others suffer. With a clean lens obviously the performance can improve.

See: http://www.laverdaforum.com/forum/index.php?topic=87238.0

and notably John (Wilson?) IIS's contribution on: http://www.laverdaforum.com/forum/index.php?topic=85643.0
 
Dirt or oil on the optical sensor will do that.
Had it on a Piranha system on a 750/4 once.
The Hall effect triggers as standard and new Sachse system from Red works better in a dirty environment.
 
Yes Grant, However I will clean the lens every now and again.

I have purchased a brand new optical sensor which will be living in the tail unit, I will be slotting the sensor plate to enable easy sensor removal/refitting should the need arise.
 
Had this problem way back with an early IIS which was traced to very slight oil leakage into that housing - it takes next to nothing to give problems.  Turned out the seal was oiltight but oil was being pushed out between the crank nose and the trigger rotor.  Refit rotor with a smear of locitie 518 on the crank nose and all was well.  That IIS opto is still a runner and has covered many 10's of thousand trouble-free k's.
Cheers
SteveB
 
Alan

I got mine from these guys.

http://uk.farnell.com/

They only cost ?7.09, although there was a minimum value order of ?20 at the time.

Their catalog ref - 1796899

Description - HOA1881-012 SENSOR, OPTICAL SWITCH, SLOTTED, 1CH 

Regards

T.



     
 
Thanks Tony,

I paid a little more from Wolfgang, but his comes with longer wiring, a protective sleeve and an AMP Superseal male plug, once the plug is installed at the free end it will fit straight in providing I follow your example and slot the mounting plate.
 
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