MZ/MuZ Riders

Having recently removed the sidecar from my bike, upon riding it the bike would cut out and be a pig to restart, I put it down to a fuelling issue and planned to look at it after i'd sorted the wiring issues from the sidecar removal. The last few days I have been redoing the wiring as the bike only had RHS indicators fitted and a non standard back light. A standard lighting set has now been installed all round and it all works as it should.

So pleased to have the electrics sorted;I thought test ride time and sort the fuelling issue; the bike would not start, went through the fuelling side and no problems, so pulled the plug to check for a spark. The plug has virtually no electrode and what was left of it looked like the end of a needle, I've never seen a plug like this before, obviously there was no spark either.

So I put another plug in and still no spark, checked the plug gap it's ok, checked points and they were tight so reset gap to spec, battery fully charged and still no spark. I guess condenser and coil to look at next but the state of the plug is a concern and what would cause it?

Engine has less than 200 miles on it since the previous owner had a full rebuild done by Burwins so should be all good.

So any ideas as to why no spark and what would cause the plug issue?

Duff plug, not unknown, I now use Brisk plugs from F2 in Wisbech.?

Broken down or cracked plug cap?

Damaged HT lead? Pulled out at either end?

Duff capacitor?

Duff coil?

Low battery voltage - does some really weird stuff, especially to electronic ignitions.

Its always a pig to chase down.

Richard

Just been to the bike shop for a new plug and yes indeed they confirmed that plug is meant to be like that, every days a school day. Anyway got a couple of new standard plugs fitted one and still no spark. I have a spark at the points but not the plug so guessing coil or condenser to look at next, the new plug is a BR8H so has a resistor, I have a spare lead and cap ill try next.

The fitting of an iridium plug might suggest the previous owner had starting issues, as it is superior to the standard plug. Its probably worth refitting if its the correct heat range, 7 or 8 ngk. I have one in my etz.

So new plug fitted, no spark, points and timing ok and a small spark across the points, new ht lead and cap fitted and still no spark, so not a plug issue. I have power to the coil and battery fully charged, still no spark.

Guessing the coils knackered; I removed it and did some tests, I have zero resistance across the terminals, in fact I have continuity and a zero reading between primary and secondary.

Puffs wrote:Well, resistivity values of the windings in a coil (particularly a 6V coil) are quite low and may be difficult to measure with a common multimeter. MZ does not give values, but they do mention the possibility of damage to the isolation due to overheating (contact on with points closed). If you have another one, it's easy to try, but you'd need another coil known to work.

For reference Lothar's excellent document: https://pic.mz-forum.com/lothar/Elektri ... ektrik.htm, where he mentions in section A.4.3 a value of 1.5±0.2Ω for a 6V coil.

With my old multimeter I measure 5.8Ω between the poles of the primary, on a (working) 6V coil from my Jawa. So I'd guess that's the range you should see: from 1Ω to 6Ω. At any rate, not 0Ω.

But I'd still try to see if I could get a spark with a non-R plug. Or just take the cap off & hold the HT lead a few mm from the head, then you should see a spark. You don't need to rotate or kick the engine, just lift the points (isolated, & with ignition on obviously). Or just keep the points closed & break the connection at one of the primary connections, that's easiest.

Have tried with a non R plug and still no spark, there is a however a slight spark at the points. Lets hope the new condenser or coil will sort the issue when it arrives, if not; thereafter I'm at a loss.

Hi All,

This is doing my head in: So Far;

Timing and points set ok, small spark at the points when opened manually, points good with no pitting
New Coil
New condenser
New Spark Plug
New Cap and HT lead
Battery fully charged
Continuity on all cables from points and generator to their respective connections and onwards as per the wiring diagram
6 volts at the coil from the ignition switch
All wiring and components check out and working as they should

BUT STILL NO SPARK!!!!!

So guessing it didn't need any of the new bits as they've made no difference, it has to be something simple, so what am I missing? I did get one spark after fitting new bits but that was it, one spark then no more! so thinking possibly a loose connection somewhere but can't find any and as mentioned continuity is good on all wiring. What am I missing here?

Anything look wrong with this pic?


Any suggestions greatly appreciated.

Yes points wire should be green but for some reason previous owner has replaced it with a new wire. The existing wire is still there with connectors. Looks like it was changed with a new wire to wire in a Gammatronix Spark Assist that had different connectors. The spark assist is still in situ but not wired in.