MZ/MuZ Riders

Hello,
Glad to have found you.
The story short of my bike:
I purchased the MZ ES250/1(1962) 15 years ago, complete engine overhaul, rode it for about 1 year. I had to move to other town and had to leave the bike behind in conservation for abot 13 years.
Now the bike got reunited with me. Got her new tires, new oil in the gearbox, cleaned the gas tank, new 6V battery. Gas in tank, 80W transmission oil in the engine(750ml), coupled battery, installed from ost2rad new electronic regulator, new carbon brushes. Primed the carburetor, 3 pedal without ignition on, 4'th pedal engine started with no issues.
Gear change is perfect with no engine running but with engine running first gear engages perfect, but after it's a mess. It is very hard to get it out of first gear and second rattles a lot when I try selecting. I have to keep clutch lever pressed and with the other hand yank the gear shifter up really hard to make it disengage 1 gear. It seems like the clutch is not doing it's job. With bike on centerstand and rear wheel up when first is selected the whel starts spinning , even with clutch actuated. When I put the bike down on the ground it has a little tendency to move forward but not much.

Now my presumptions:
1. too think gear oil: i read in manual motorol SAE40 which tells me that 15W-40 mineral motor oil would be perfect.
2. incorrectly adjusted clutch > I played with the adjusting screw turning it almost all way out but still same behavior > i cannot find correct adjustment procedure
3. Sticking or very dirty clutch disks, even it is weird that with 1'st engaged and clutch pulled in the bike will not have a very hard tendency to roll forward.

Please if someone is able to provide some advice I would really appreciate. The bike will go to MOT and after will go thru an extensive restore like replating chrome, repainting etc... process.

MZ says gearbox oil 80 W GL3
This is a very pure oil with no additives.

Modern gearbox oil have special additives that can cause the friction plates to "grow" and thus the clutch cannot work properly.
The same with 10W 40 engine oil or similar.
40W is a single viscosity oil, but this oil is not used in modern engines, so it is hard to get.

I found simple 40W at motorex and ravenol. They make it special for oldtimers. In winter book says SAE20 .

Anyway I will put 15W-40 motorcycle oil just for a wash and replace it. with proper oil SAE40.

Any others have some guess of what might be my issue?

Maybe it's just that the metal clutch plates have stuck/fused slightly? Maybe some riding around with and without the clutch engaged in an area which is not stressful (like a nice long road- not in town traffic), to 'exercise' the clutch a bit?

If this was the case the clutch would stuck completely, but it seems that it is not clearing completely, so the discs are turning

Hmmmm.
During the first oil change I did, i mistakenly took out the locking screw which locks the neutral position but very very carefully put it back along with the steel ball. I did not press any levers with that ball and sping out so I see no issues here. After that I verified and shifter works perfectly.

Maibe my final drive chain tension is not right? Now it is really really tight with no play in the chain. What us the recommended chain play so It does not run on the crankcase or the chain protector odf the rear wheel? Spaces there seem very tight.

Found the specs. 10 mm up and 10 down of chain slack. Mine wa in specs so no issue here.

So I was very wrong ... I measured the chain slack with bike on stand....with rider on bike on the ground the chain was extremly tight. Readjusted to spec.
Remains oil change and now to change a broken fuel tap. So until tommorrow expecting new ideas of what could cause the gearbox to behave like this and maibe some sugestions.

Thanks.

Hi,

Make sure when you make your chain adjustment, that you do it at it's tightest spot- as the chain stretches through use, it doesn't stretch uniformly over the entire chain but in areas. You will see the chain tightness fluctuate as you spin the rear wheel with the timing cover off..

this oils seems good:
CASTROL POWER 1 R40
or RAVENOL CLASSIC 1 SAE40
MOTUL SAE 40

????

No more ideas? Do we have some mechanics around?

Well, have you taken the bike for a ride then?

It does seem like a clutch issue.
Take it for a ride, get it warmed up for the oil to circulate nicely through all the parts.
If nothing else, atleast you'll get an idea for how the shifts feel without the resistance like when stationary.

When I got my TS, the clutch was completely stuck. I managed to get it unstuck, but was still sticky and problematic going in and out of gears. After a ride it started operating nice and smooth.

I'm afraid I don't have any experience of the 4 speed box. I have heard the gearchange described as 'agricultural at best', but I'm sure it should be better than you are describing!

As you mentioned in your first post, I would check the clutch adjustment first - it does sound as though the plates might not be separating far enough. This, as far as I know, is effectively the same as the later 5-speeds I'm more familiar with.

Clutch adjustment can be divided into two operations: 'coarse adjustment' and 'fine adjustment'. The coarse adjustment should be carried out with the cable disconnected at the engine end, and the steel sleeve screwed into the clutch cover removed. If you remove the round plate from the clutch cover (held on with 3 screws) you will see a steel plate beneath it, which locks the position of the external part of the clutch arm's helicoid. This plate and the helicoid should be rotated so that the distance between the hole for the cable nipple is 11mm from the edge of the clutch cover.

When I had a look on Google for some photos I came across the following video link, which makes it much clearer than my description!
https://youtu.be/6ptXHE2i0x0?t=50m13s

Once you've done that, you can carry out the 'fine adjustment' at using the cable adjuster at the handlebars.

If that doesn't work, I would start to wonder whether the clutch itself is assembled correctly....