Appeal to the Laverda nuts on here!!

Some of you are aware that I have a friend with a 3C which came to him as an almost complete resto but has turned out to be a bag on nuts (apart from a complete engine rebuild by those nice guys in East Anglia - the name evades me). Colin has had the bike for about 9 years and in that time he’s probably ridden it no more than 100 miles. The main reason has been to do with a string of failed ankle operations but this Spring he decided to try and finally nail the problems and get out and about on it. He’s had the carbs fully rebuilt. Everything has been changed - jets, chokes, you name it - if it comes off its been replaced! The bike is still temperamental and we have this constant battle trying to decide if it is fuel or spark (nothing wrong with the spark when you check it though).

One of the first things he did 8 years ago was to fit a Witt DMC 2 electronic ignition with new coils. We are now wondering if this is the cause of the problem. Today, when I went to start it I turned the ignition on and there was a ‘crack’ noise a bit like something arcing. That was before I’d hit the starter. When it started, you could still hear a ‘crack’ from time to time. Colin’s been right through the electrical system checking for faulty cables, checking earths, and so we now want to see if we can get our hands on another Witt to compare. It might be 8 years old but it’s done no work at all and we’ve been reluctant to think this is the problem (also because of the cost of a replacement if we can’t find one to borrow!!)

Just putting this out there and would be interested in any comments from Laverda owners on here.

A few years ago I had a 1200 jota 180, very temperamental only firing on 2 out of 3 cylinders part of the time but not always, ended up being a £10 fix, each coil is held in a metal cradle, one of my cradles had a fracture in it, barely visible unless the bike was run in the dark with the tank off.
Renewed the faulty cradle and all was good.
Worth your mate checki g, you never know.

Have you tried running it in a dark garage? Preferably on a temporary fuel supply with the tank off.

Running it in the dark is what he’s going to try tonight. Will report back!

Maybe the coils are arcing across themselves, that would make the crack sound

Witt DMC2

Robbi said:

Maybe the coils are arcing across themselves, that would make the crack sound

Click to expand...

These are very reliable ignitions, but rely on the original pickups, has THAT wiring been replaced? I've just rewired a friend's Ducati Darmah with the same pickups (though they run in oil on the Duke compounding the issue), that was a bastard to start. Just putting decent wiring and earths to the original Bosch box has produced a great starter.

Also there's a test position on the DMC2 (position 0 I think?) which gives a spark on all plugs every second or so, really useful for, er, testing! Darkened garage as has been suggested, though you often get a "wasted" spark on turning on the ignition so could just be a plug/s firing normally?

If it's a misfire I find those cheap neon testers (a few quid on ebay) that plug into the ht lead between the lead and the plug, useful at twilight for seeing if the plugs are firing normally. Of course you can't see the middle plug which uses a different coil and pickup to the outer two, but it all helps in the elimination game. You can then swap the coils (and all the attendant wiring and leads) to test coil that was on the inner plug.

Don't use resistor plugs (just about all there is these days) and resistor plug caps (Green spark plug company does non-resisitive NGK caps for example).

Finally the TDC marking on the ignition/generator rotor isn't always accurate, check that with a TDC stop or similar if it's running rough?

Whereabouts in Worcestershire are you, I'm in the next count up (Shropshire)?

Dave

We're just outside Great Witley.

Colin's now been right back through the earthing system and also disconnected and reconnected all the DMC connections. He thinks it is running with less of the 'cracks' now and I'm going to take it for a spin tonight when I'm back from work, just to see what I can hear and how well it will run.