New ES250 Trophy Project!

[Puffs]

You say "With the lights on, the bike mis-fires and stalls at idle.", I interpret that to mean it runs fine at higher revs, but you get the misfiring & stalling only at idle. That is when the voltage is lowest - how low? Below some voltage (5.0 - 4.5V?) the coil may not reliably develop a spark. Then yes, it is a case combining low voltage from the generator, with a battery that can not cope with the loss of the generator voltage, as described in "V.4.1 Battery is not sufficiently charged, engine cuts out when idling".

Alternatively, yes, it is well possible that the drop in voltage across a junction in a friction held fuse (in combination with vibrations) is what kills your spark. Poor contact, while high current is required. But it is not necessarily a 'resistivity' issue (in the sense of Ohm's law), what happens is that below a certain voltage, no current at all passes through that junction. That is exactly what I mentioned I had in my fuse box, in my 12V ETZ251.
To check, temporarily bypass that fuse with a dedicated cable.

On other thoughts, the only coil issue I'm familiar with is loss of continuity (and then no spark at all). A hot coil could result from the points being closed for too long (dwell time). With the points closed, a high current flows through the primary side of the coil, and this will reduce the voltage, particularly if the battery is weak. The voltage at idle is not really a constant value, it'll wobble around some mean value, with lows when the points are closed, and highs when they are open. The battery should act as a voltage stabiliser.

The condenser might leak a little bit, and this might cause your symptoms. But I'd think it's an unlikely cause, and the only way to test is by replacing (unless you can measure a DC leak current). Low PoS.

Similarly, points: not likely. Stator windings: not likely either.

OK Dave47, now I see what you mean by 'switchgear'. Are you sure the indicator switch, as found on the LHS on the 12V ETZ251 would not work at 6V? Would that Chinese-made switchgear work with a modern solid-state flasher relay (rather than the conventional relay with an electromagnetic coil, which draws more current)? Again not really a fundamental 6V issue, but I'm not sure you can find a modern solid-state flasher relay for 6V.
Btw, neither of my 6V bikes have indicators.

Yes, I too have used my phone for navigation, on the 251. Made a bracket for it. And yes, the phone's battery doesn't last long when you do that, the GPS apparently draws a lot of current. I've been using that phone for the same purpose in the car for years, then connected to the cigar lighter socket with such an USB PSU gizmo. That gets warm, so that too might simply be too much power for the ES's generator. Surely the 210W generator in the ETZ251 could supply it (if I made something for it), but again, you're just hitting the limitations of older technology in an old bike. So if that's a priority, an upgrade is required.

[Blurredman]

Okay been working on this this morning. Focusing foremost on the fuse 'box'.

For a start the battery is in good condition. Bearing in mind I ran last night with the lights on the standing voltage when I measured it this morning was 6.25v.

I did some tests with the multimeter:

battery 6.25

idling no lights
6.15 at battery, 5.98 at fusebox (loom side)

w/ lights
5.85 at battery, 5.25 at fusebox (loom side)

Then I did a bit of rigging of wires to essentially bypass the fuse/box.



And got the following:

idling no lights
6.15 at battery, 6.15 at fusebox (loom side)

w/ lights
5.75-80 at battery, 5.75-80 at fusebox (loom side)

So it's obvious there is significant draw at the fuse box, the fuse connection, or wire connections. It's worth noting that the charge light only glowed at idle after rigging my wing. Unlike before when riding the charge light would be glowing very dimly (w/ lights on, even before this stalling issue occurred more often), giving the bike a small rev the light immediately stopped glowing. More so, the intermittent 'missing' seemed to disappear too so definitely on the right track to start with.

So, I've cleaned up the spade contacts and crimped down the connection tangs slightly too, but additionally also changed outright the positive wire spade connection on the loom. The fuse box itself isn't in good condition with broken connection tangs (no earth fuse, battery is directly connected to loom) and also split sections too- so need to replace that (always intended to anyway actually). I've cleaned it up as best I could and tried to solder the cracks in the metalwork but that's the best I can do for now with this box, anyway. But for now the bike is back together with the fusebox and everything connected.

After all that I get 5.75v @ idle with lights at direct connection (bypassing fuse). But through the fuse box 5.65v. It's also worth noting that fuse orientation can also reduce this to 5.55v.


Bike doesn't seem to misfire at idle or stall, at least whilst in the garage. The real test will obviously be to use the bike when I can and return my results and then if not favourable continue with my diagnosis.

[Puffs]

I think I see a similar sort of fuse box as my 251 has, only I have 4 fuses, and you 1 or 2.

OK, so initially you lost quite some voltage over it, but after some work that improved. And for now it seems to run OK.
Yours may be suffering from the same ailment as mine did, occasionally, when it still had to do wet work. Haven't had it in years, since it only rides in fair weather. I blamed mine on corrosion at the contacts.

Fingers crossed...

[dave47]

Blurredman, There is a widespread belief among MZ owners that replacing the ceramic fuses with blade fuses is a good thing. Why not do that? They are less trouble. I have replaced the fusebox with simple inline fuseholders - about £1 each.

Puffs, The early ETZ250 switch was suitable for 6v or 12v electrics - no idea why - but it was redesigned in the mid 80s with thinner wires.

[Blurredman]

I have put bladed fuse boxes on my other two bikes (ETZ's) so I know the advantages of using them, and it is likely I will use an inline fuse with the positive feed in the future.

But, tonights progress? I went out this evening and it was not a success, infact it was potentially worse i'd say. There was no change to the stalling at stops and misfiring at low speed/rpm conditions. Infact by the time I got home it was almost unusable. And actually I now has suspicions on coil, or certainly something seems to degrade the warmer/longer the bike's operation continues. As I say when I got home it was unusable with the lights on at all, with stalling being a common issue and a backfire as the bike stalled. This is what leads me to think about the coil maybe being an issue?

Problem is, I don't have any other 6v MZ's, so I have no spare coil I could try, unlike the fact I have plenty of 12v MZ spare parts..

So, disapointed.... and the diagnoisis continues.

[Jay Bee]

I have put bladed fuse boxes on my other two bikes (ETZ's) so I know the advantages of using them

Don't mean to hijack your thread, but I have toyed with the idea of replacing the O.E. fuse box on my ETZ 125. The only bladed type fuse box I've seen has just single male spade connections ; how did you make the multiple connections ? I am concerned not to add to the number of unreliable connections I already have....

[Blurredman]

I have put bladed fuse boxes on my other two bikes (ETZ's) so I know the advantages of using them

Don't mean to hijack your thread, but I have toyed with the idea of replacing the O.E. fuse box on my ETZ 125. The only bladed type fuse box I've seen has just single male spade connections ; how did you make the multiple connections ? I am concerned not to add to the number of unreliable connections I already have....

You're right, on the ETZ (and actually on the ES) you need a bridge between two connections before it gets to the fuse. Therefore, on both my ETZ's I have a spade connection with a piggy back on the wire coming from the battery. Then the wire from regulator jumps on the back of that.. Then through the fuse holders.. It's a neater way to do exactly the same as I have done above on my picture (although those wires were just testing wires so didn't need to be neat).

[Jay Bee]

Thanks, Blurredman - That's exactly what I imagined.
I don't want to sound sniffy about it, but I hate pre-insulated terminals with a passion and I wouldn't use them on any bike (or car).
If I do change the fusebox I'll have to explore other connection methods.

[DAVID THOMPSON]

I remove the plastic part and solder them on
i have a soldering gun that runs on 12 to 19 volts

and they can often be reused if needed for repairing a bad wire

i some times solder the new blade fuses in the circuit and
use liquid tape to paint insulation on open connections

on my 660 Traveller i soldered the coil to the harness after having the spades
become disconnected several times

[Puffs]

Getting back to the ES: you could try with a 12V coil.

An ignition coil is a step-up transformer; the change in current (when the points open) in the primary coil causes a change in magnetic flux, which also passes through the secondary coil. In the secondary coil, that change in flux causes a high voltage spike, which is sent to the plug; both the ratio of the number of windings (#2nd/#1st) and the current at the primary side play a role for the output voltage. I really do not know what the lower V limit is, yet a 12V one you have readily available.
While the inductance might be similar, Lothar states 1.5Ω for the 6V primary & 4.5Ω for the 12V one, so you may get a weaker spark due to a much lower current.

There would be 3 outcomes:
1) it doesn't work at all --> 12V coil is no good @ 6V.
2) it does the same as with the original coil --> it's not in the coil
3) problem solved --> your org. coil is faulty.

In case #1, which is quite possible, you've learned nothing, but haven't spent anything either.

If #1 happens, maybe you can also de-couple the generator/regulator/rectifier, keep that 12V coil & place a 12V battery, see how it then runs.

But it may not be in the coil at all.

Looking at Lothars document again, section A.4.2, wrt the capacitor/condenser, he says: "Failures that only occur at engine operating temperature and "heal" again when cold are possible.". I think they're the same for 6V & 12V --> try another one?

[Jay Bee]

Thanks, David -
To solder, or to crimp? has long been an issue with motorcycle wiring, and which option you are more comfortable with, a personal matter.
I suspect with your interest in radio that you are an accomplished user of soldered joints.
However, I have always been persuaded to believe that the way to go is crimps ONLY, just as the factory did when they originally made the bike.
I am currently in the throes of re-wiring three British bikes : 2 Triumph 750's and a 6V. Royal Enfield Bullet which I am converting to 12V. All of these have an absolute bare minimum of soldered joints in areas of little movement or vibration. All other joints are crimped.
Blurredman - I apologise for the interruption to your thread.

[Puffs]

Indeed, the issue with soldering is that the solder flows around the wires, also away from the solder point, which makes that part stiff. But bikes vibrate. The section of the cable, just beyond the bit that was stiffened with solder, may then flex under those vibrations, and break.

Nevertheless, I also solder on bikes. Try to prevent cables vibrating.

[Blurredman]

When it comes to re-wiring, I also pull off off the plastic bit just as David does. I also much prefer to use solder rather than a crimping tool (don't actually own one myself). I take the plastic thing off. I tin and trim the wire end, then I fill a certain amount of the spade wire receiver with solder (using the iron - 25w iron here) at the back to help it flow through. Then whilst still hot and fluid I push the wire in. The solder that is already in the receiver flows with the wire and makes a solid join with the receiver. I think it's the best practice. I think partly factories mostly do crimping because it's cheaper and much quicker to make up the cables that way. More so, factory crimping is very different to the cheap crimpers you get on the market for the public. They crimp differently...


I did do some more indepth testing last night specifically regarding ignition components. The coil checked out at 1.5ohms between terminals 15 (+) and 1 (-), and 7.5k ohms between terminal 15 and the secondary winding (plug lead in, yes taking into account the 5k resistence of the cap).

I checked the stator windings and got 1.7-2ohms there too which is by the book. Additionally, I checked the variable resistor and that was 4.5ohms (by the book) and the capacitor resistence was below 1ohm which also checks out (in terms of resistence- I don't have a capacitence meter to measure the capacitence itself). But as I've previously discussed, the fact that the bike doesn't mis-fire at speed and the points aren't pitted pretty much rules that out anyway as that is the major side effect of defective condensor/capacitor.


The bike was running fine after putting it back together including idling without mis-fire, but noticed the slight touch of the fuse DID give the mis-fire. So I soldered in an in-line fuse that looped around the fuse box (making use of the terminals). And I went for a ride but it was unsuccessful again. Fine when riding, but stopped w/ lights on (and even with lights off) it mis-fired at idle, and indeed would stall w/ lights on uite readily. I did wonder about the idle rpm but I really think that is in good adjustment and sounds the right rpm so I left it- besides, I never touched that in a few hundred miles.


When I got back home I made a small video (attempted to anyway, but just after I re-started the bike after stall and turn lights on the phone died- but that's okay, because you can hear the misfire and what is happening), but my conclusion last night that it occurs with the lights off, made me wonder about the battery voltage.

I checked the coil, and primary winding was 1.5ohm, and secondary was still about 7.5k ohm (7.3k). So.. Looks like not a coil... Despite your good idea Puffs, that might have to wait until

I did check the charging voltage again and the peak performance was 6.45v at battery (w/ lights) revving very high so the results lately seems to vary a bit there, which is interesting considering I saw 7.3v at the same RPM the other night. I checked the voltage of the battery just before I called it a night (after pottering around doing other things) and the battery read 6.07v. This morning it read the same 6.07v. I wonder.... Though worth mentioning that voltage at idle was still 5.8v with lights on when it was idling perfectly fine before I decided to head out on it.



So.... the battery is now on charge (proper 6v charger), and my intention is to use the bike for work for a day. First day i'll ride it without lights, but wednesday I will use it WITH the lights. See how it runs at idle on the commute and check voltages on the morning after (both tomorrow and Wednesday), and compare, but also compare my experience with the idle quality (notibly with a fully charged battery w/ lights, whether I still get issues).


I've decided to do the above test before I decide to completely replace the the fuse junction box and to eliminate voltage drops in that area- it's quite possible the terminal 51 of the regulator hasn't got the best of connection at the fuse box (terminal 51 I believe actually provides the link of balance load) , and I created the piggy back connection on the in-line fuse, and not the battery wire, so the regulator + still does go through the fusebox junction box. So yes, what I think at the minute is that there is a voltage loss at the fuse box and that is overcoming the charging capability, that is my feeling at the minute.

Food for thought. I suppose thinking about it, it does feel very much like what happens when my battery is getting low on my 12v MZ's.. They do this 'stumble' thing, and then stall, and most of the time give a big backfire.

EDIT: Ride to work on the ES was not successful at all to-day.. It wasn't going badly.. the battery was at 6.31v after standing overnight (charged for 10 hours yesterday), and as always when cold was idling perfectly happily.. But slowly on the way to work, low speed/rpm situations had the bike mis-firing slightly at first but then getting worse and worse to the point that by the time I got to work I had to keep the throttle at est 2k + rpm throttle just to keep the bike from stalling fully. (never turned the lights on during my trip to work this morning). I'll test again the coil when I get home, but it's really perplexing me...!! Something which isn't so obvious as a simple charging problems it seems.....? I'll definitely be on the ETZ298 tomorrow for work...

[Puffs]

Mwah, crimping... if required I may use some other pliers (though I should have a sort of 'official' tool slightly younger than my vices).

I once had a coil that gave perfect Ω values on measuring, but still was the cause of the bike not running (as it ran fine with another coil). But that bike did not start at all.

Capacitor resistance? Of less than 1Ω??? I do not understand that, or that will surely be the cause you have no spark. The capacitor is in parallel with your points/contact breakers, and if you put a 1Ω R there it's the same as if the points never open... But yes, there might be an Ω-like leak in that capacitor/condenser, which would have a much stronger effect when the voltages are low, hence at low revs. So little arcing & running fine at high revs are insufficient to conclude it's not the cap. Again, the most conclusive way to test the capacitor is by replacing it with a known good one, IMO.

Anyway, so you found earlier there was quite some voltage drop over the fuse, and now that if you touched the fuse, you did get the problems. Then you soldered an in-line fuse, apparently still making use of the same original crimped terminals. And then you still had the problems! Would that not suggest there might also be an issue in those crimped terminal connections? So, did you test with a (temporary) soldered wire also bypassing those crimped connections to the fuse box? If not, that still seems an easy test worth trying.

Btw, if you find the pressed contact connections to the fuse to be the problem (rather than the crimped ones in the cables to the fuse box), you could consider to simply solder the fuse in place. Bit of a hassle to replace the fuse at the roadside, but in all honesty, that is virtually never required.

Fluctuating max voltage (less now than the previous time): are your brushes good? Collector clean? Or indeed regulator...

And yes, all connections in an almost 50 year old bike (that's been in a flood) are suspect, and could be the cause...

The video doesn't tell me anything. The 1st time it just stalls uneventful, and after starting, you switch the lights on, and the video stops...

[Blurredman]

I barely made it to work yesterday morning, and I barely made it home even worse.. Bike was perfectly happy cold, but gradual mis-fire and stall at idle (when waiting at lights for example), gradually got worse and worse and worse, and indeed on the way home the bike stopped completely. I can't say how embarrasing it is to be sitting at lights in rush hour traffic having the bike revving @ like 4k to keep from stalling.

Anyway, When I got home I IMMEDIATELY swapped the condenser with the one from my ETZ250 (both condensers are 0.22uF 250v, which is actually pretty standard it seems for most automotive condesnsers). And the Trophy was exactly the same. Wouldn't idle, mis-fire, backfire. Not happy. I put the condenser that was on the Trophy on my ETZ250 which I used yesterday to go to the shops and also to-day for work, and the ETZ250 is perfectly happy... No issues at all. Last night I did try (with two) 12v MZ coils on the Trophy but I got nothing from the bike other than backfire. Fails to start at all. Oh well, looks like I am on the search for a miniature 6v coil....!

The one that was on the ES250, indeed is an original MZ one, though it is dated '77 (but interestingly enough does say 'TROPHY' on it), and also DDR etc. I just find it interesting how it seemingly worked for 650miles.

Yes the video is poor. I did say the phone failed after I attempted to get the bike back down to idle. Anyway, I guess not required anymore.