New ETZ 250 rider here and some questions

[klemmy]

Hi there,
Im new member here and a new rider of MZ ETZ 250 from 1984-the same year of production as I am Im not from english speaking country, so please excuse me for my english. Its a bit rusty.

MZ was quite popular brand of motorcycles in my area(ex Yugoslavia) mostly because there were almost no other thing avaible. As soon japanese motorcycles came over, people started to turning away from brands which came from ex communist blocks and MZ was no exeption. Altrough it has a good reputation for been very robust and realible and also a cheap motorcycle, which is rather an exeption for a product, which came from communist country!

I remember since I was a kid and teenager, how sweet was a smell of two stroke and characteristic "rin din din" sound, when there were quite popular on the roads, so I decided to finally buy one, whish is at least in desent state. Im not perfect, so why should MZ be?

Ok, the question is about speedometer. It is so jumpy, that is useless. I understand, that I have to open the housing and to clean and lubricate the mechanism. The main question is, how to get the speedometer and rev counter out of the holder, without breaking anything? They should just slide out of the holder and rubber protective cap or something? Mine looks like they are stuck there.

Thank you very much for your answers

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[dave47]

The mz clocks can't be opened for maintenance. Your problem is more likely to be the cable being loose.

[Jay Bee]

Must disagree with Puffs here - never oil a speedo. cable, particularly at the top end. Oil can work its way upwards into the instrument and cause havoc.
I wouldn't put ordinary grease anywhere near the speedo. head exterior or the rubber cup either, although silicone grease would probably be OK.
Verify that the speedo. cable is in good condition from top to bottom - no kinks or damage to the outer sheath and has as smooth a run as possible - no tight bends. Disconnect the cable end and remove the inner cable, clean, coat with grease (leaving the top 12cms. or so clear) and re-fit. If this doesn't fix your problem you may have to look at the drive mechanism in the rear chaincase.

[klemmy]

Thank you very much for your answers!

I will try my best to find the solution for this jumping speedo

Next thing....The good old MZ clutch...

When I bought it and the previous owner was kind enough, to let me on test drive, the clutch was kind of slack. It was practically impossible to get into neutral, when engine running.
At home I order a new cable and changed the old one with all the instructions I found on youtube. The cable adjustment on a lever made neutral much easier to find.

The clutch is making all the right noises. Im not sure about one occasionally "klonk" sound, that it seems to come from clutch side....anyone in maybe familliar with that? The engine was rebuild by professionalls about 2200km ago
and clutch itself and components were just inspected and they concluded, that is OK.

Maybe some bearing or washer clearence?

Thank you for all answers

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[DAVID THOMPSON]

they make gps speed meters for boats use one of those with a regular12 v battery and a charger
they tell how fast your going but not how far

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[klemmy]

Oh, Puffs, Im sorry, I missed your question about kilometers on the clock...Its 1149,4 km on the clock, with zero in the front One option is, that counter went back to zero after it pass 100.000km, or they "adjusted" it back to the zero after rebuild of the engine was done...I really doubt it is a genuine mileage from 1984 The weather here does not allow me, to do some serious road test at the moment...I just rode it around the block for a few times and so far, it feels OK.

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[klemmy]

This is very useful, thank you

I finally made a bit longer ride, about 40 km and I had noticed, that at about 90km/h the counter calms down and its reading the right speed...at lower speed it is jumping again.

The bike rides generally well, it idles a bit high, but nothing dramatically....There is one thing, that bothers me and that is some strange deep, but not particulary loud knock or thump sound, when you close the throttle, or when you are riding down the hill without throttle at low rpm. That happens only when you ride the bike. My first thought was, that there is some clutch clearence or driving wheel for primary transmission, but al the gears goes up and down shift very smoothly.

The carburettor is probably original BWF 30 N2-5, ugess is a ltttle bit tired, but a mixture is judging by the spark plug color OK. Mine second thought was, that there could be a exhaust leak between pipe and cylinder, judging by the unburnt oil residue, which is located in small amounts under the coupling nut. But when bike idles, there is no smoke to be seen coming out from there...

Any suggestions, please?

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[klemmy]

It could be so called "surging on the overrun", the only similar sound I found on youtube is this: from 0.45 to 0.58 and this is of course carburettor related issue https://www.youtube.com/watch?v=G1CUHSWV7sY

And another one, just briefly and not clearly hearing 10.16 to 10.18 https://www.youtube.com/watch?v=H_eNHFHaJ0U&t=638s

Maybe someone has a video with better and easily recognizable sound of this knock/thump

Thank you very much for your help

[Blurredman]

Hi,

Those noises are quite normal. You'll often get them mainly at high speed from 60 or 70 mph and shutting the throttle quickly and then on over-run slowing down, but also in a low gear at high speed, most notibly when going down a hill for example.

I don't think you have anything to fear there. It's as Puffs says about the way the compression cycle is being fired at that point with little fuel input at a relatively higher RPM.


As for your possible exhaust leak, it is likely there could have been but the very fact that carbony exhaust gasses has gone through the gap has likely closed that leak up and that is why there is no obvious exhaust blow..