Das MZ Forum für MZ Fahrer

Hello team,

I find that after three or four hundred miles the spark plug will be prone to fouling, and once it's fouled I find that it cannot be cleaned to be useful again. I am using NGK - B7HS. My parts vendor has offered a NGK iridium 1 range hotter with a resistor... B8HS. Is this logical? Spark plug colour pictured for your evaluation.

Thank you.
M.

Hi M.
your plug looks good to me for the next 5000mls. B8HS is colder than B7HS, so you can try it without the danger overheating it. BR8HIX is the Iridium-type.
With unleaded fuel and (semi)synthetic twostroke-oil there is usually no plug-fouling. I use B8HS in my sidecar TS250/1,(mostly full throttle...) and didn't change the plug for more than 10.000mls (16.000km) without any problems.
There are several people telling, that iridiums do not work good in twostrokes. I love them in old fourstrokes, but never tried them in twostrokes,(except my '86 TY250-trials-bike) so I can give no recommendation.
If you feel that your bike has a high plug-consumption, my experience is, that there is a ignition problem. Mostly a weak spark, caused by a weak coil or bad points.

Cheers,
Hans

Good description from hiha. Nothing to add.

Color looks nice. If u have ignition fault´s, look for the ignition way (wires, coals, capacitor(to old?), distance at at circuit breaker. and distance at the plug electrode., at least not enough fuel running through the carburator(but i dont think so)

Perhaps the 44 year-old coil is coming to its end.
M.

And never underestimate the capacitor. If you replace it, don't use a chinese-cheapo-crap-one. I don't know good ones in USA, but I'm shure your local old-timer-Harley-dealer can recommend one to you.

Hans

Hello Michael,

the spark plug actually looks pretty good, not a cause for alarm. But, are there any problems with the sparks or are there any interruptions?

Is the coil becoming very warm or hot in use? Did you turn on the ignition for a long time and the engine was off?

In case you would like to try a new coil, then try to find a ZS 215 from Beru like this one http://www.auto-teile.com/ersatzteile/e ... 8229_0.htm. That was a wonderful remedy for my machine.

PS: Watch your postbox in the next few days (or weeks ). Wishing you happy holidays and greetings to your family.

Best regards

Frank

Thank you for the suggestion about the new coil.

To answer your question.... when the spark plug is two or three hundred miles old if I happened to carelessly started with too much choke or stab to choke when I'm running just to see what happens... when the bike hesitates or bogs due to excess fuel, it starts misfiring at low RPMs so I have to ride bike at high RPMs so it doesn't die.
If it does die then I cannot started. Then I have to change plug in the middle of traffic.

Coil is warm, not hot when underway.
I do not leave key on without running. Always use German source parts. False economy to try to save pennies.

A parts vendor provided me with an iridium plug that has a resistor. I know resistor can raise the discharge voltage a little bit. I hope it does not strain the old coil.

I will do a voltage drop, over my connections for ignition circuit, and ohm check the coil.

But the coil you suggested does look pretty. I'm am concerned that I am not using Beru plugs....

M

-- Hinzugefügt: 21. December 2018 16:33 --

Sunday the 16th of December

-- Hinzugefügt: 21. December 2018 16:35 --

Also u change the plug and the 2 minutes later she will run again for 1-2 miles or a bit longer and die´s again? till the next change or cool down? Than it sound for me that the capacitator is the one that u dont like.

naa

it runs 300 to 400 miles.
M

The TS250/0 is still acting out.

I have not found the cause to my concern yet but we will narrow it down.

I have noticed on a cold day that the idle hung up and didn't come down.

Checked the slide, and it was not sticking. Enricher (cold start) was seated correctly.
Idle was a normal burble after I changed a plug.
ohh-

forgot to say that MZ Stalled and would not start(same issue as in my previous post) put in the plug that stalled the bike in November, and drove another 25 miles, then went home.

The temperature was 8 Celsius on the road. Not bitter cold, but cooler than I normally go out in. As an aside the bike has a nice fat blue spark.

Somthings acting up...... I've noticed the problem manifest itself right from a cold start from Storage. If it doesn't run nice and crisp, from the get-go, but rather , smokey and blubbering (four stroking) I will be guaranteed to have trouble one mile up the road when it acts like it's loaded up and drowning finally stalling at the first stop and not restarting.

I do have a new Gusi condenser so maybe I will swap out the 45 year old condenser. points are new. wires cables new. :- )
M.

I would change the condenser, like you mentioned. If the failure is still the same, change the ignition coil, like others wrote before.

Fuel level in bowl was high.

Lowered the fuel level 1.0mm.

Bike runs very well in 8c to 15c weather...

Why did I find it high? I don't know.

Hello Michael,

From my personal experience (also with Ducati, Harley and Dnepr bikes):
NGK spark plugs are extremly sensitive when coming in contact with too much unburned fuel.

It feels like the isolating material around the middle electrode is acting like a sponge.
After drying the spark plugs on a heater for hours, the plugs could be reactivated for only a short time.
I still use NGK in several bikes because they work best (just my personal impression - nothing measurable). But I always have some spares in my pocket...just in case...

So you might think about changing to another spark plug manufacturer - just to make sure if the misfires are really caused by the plug.

Many thanks for sharing your experience.

Do you have any opinions on a more robust plug to deal with the fog of pre-mix in a cylinder?

M.

Hi Michael,
I would swap to a Champion plug if it's too complicated to get an "Isolator" plug. They solved the same problems that I had with a Suzuki GT. It had 2 different heat ranges, for City or Highway. The "cooler" Champion that normally was correct for highway was capable to do the city driving and even traffic jam.

Hi Michael
I was running a French plug from a 2CV for ages, which a friend gave to me.
http://www.franzoesische-klassiker-shop ... yquem-755X
I think it is still there. Never had troubles with it.

But your problem rather sounds like a main seal (crankshaft) starts to play up:



That should be the left seal, oil from the gearbox may be sucked in and foul your plugs.
A new plug does fix the symptoms for some time.
You could do an oil change and check the old oil for petrol smell to verify.

Andy

... update,
275 miles later still running great.
the correct float level has fixed the problem.

Hi Michael,

that sounds very good. Sometimes you first go in the wrong direction and then it's something completely different.

Have fun with the bike.

Regards

Frank

PS: Is there any snow left on the bridge?

Happily the snow has melted! Now we have rumblings of thunderstorms to amuse us and wash the roads clean.
Michael

Same here in Munich, but still cold.
Hans