MZ/MuZ Riders

Folks,

I finally got to "unmothballing" my 1974 MZ TS250 with 1750 original miles. Bought it at Mecum in Jan of 2017 over the internet for $1250. Bike was well prepared for storage and that paid off today.

I put oil in the trans case and mixed gas in the tank and tried to fire it up. No dice, so I pulled the carb off and used jet files to clean out what looked like a very clean carb. But the idle jet needed some love for sure.

Tried again and realized there was probably something up with the ignition. The points almost didn't seem to come apart at all. The looked stuck together. Adjusted those, and now the bike starts, but it is seemingly only firing occasionally. Played with the low speed screw and I can get it to not stall and even rev a little, but it still seems to miss at least 50% of the time. The thing came with an NGK BR9HS plug which is like the coldest plug NGK makes in the B series. Maybe that helps?

Any thoughts or posts you can point me to?

Also, I am sure this is common, but just about every piece of rubber is in bad shape on this bike. I am assuming it is OK to pull off the chain and rear sprocket covers. Any real concerns there?

Thanks!

Thank you for your response.

All good and high valued information.

I'll make sure the plug setup is as non-resistor as possible. Battery was fully charged.

I can set the points gap clearly, and will clean up the points faces.

My main question at the moment is how to set the timing. I don't want to pull the head off and I don't think one of those TDC tools for the spark plug hole will work for an offset spark plug like the head I have.

The timing disc has a lot of tick marks in it, just that I am not sure at the moment what to align with what.

How do you normally set timing?

Thanks again,

MG

Puffs,

Sources a B7HS plug today and to my surprise the bike fired up and ran good. Seems to me the BP7HS is not platinum, but protruding tip. Based on the head design, that almost seems better to me.

Now all I need to do is get those chain guards off and do some round the block tests for shifting and brakes.

Keep you posted.

If you do get a chance to answer how you set your timing please do.

Also what do you run for transmission lubricant?

Thx!

If you've got a timing disk and can securely attach it to the crank, here's a method for finding TDC with pretty much 100% accuracy...

1. Drill/smash the centre out of an old spark plug - make sure it's completely clean with no loose bits hiding.
2. Find a suitably sized bolt to go through the middle with approx 2 or 3cm protruding from the lower end of the 'plug' and tighten a nut so the bolt is tight and secure.
3. Screw this device into your plug hole
4. With the degree disc attached, rotate the crank forwards until the piston crown makes contact with the bolt - note the degree reading
5. Rotate the crank backwards until the piston crown makes contact with the bolt - note the degree reading again
5. Half way between these two readings is TDC - you can reposition the degree wheel to show zero if you want or just subtract your BTDC from there
6. You should now be ready to go with setting the timing.

Thanks folks. I'll check the manual again. Didn't see it the first time through.

Are you running 60w gear oil? I can order some, but the local autozone didnt stock it. They had 75W90. But no 60w.

OK Puffs, yeah we are in sync now. That was my point with this technique. I also thought that TDC could be easily read, but BTDC by any accuracy with mm would give Pythagorus some sweats.

My update from today is sort of mixed in good and bad.

I decided to test ride today after making sure all cables were well lubed over night. I also had to cut the rubber covers off the chain. Seemed easiest given they are 1 piece and not expensive to replace.

I think there is something wrong with the clutch as it just sort of grabs all of a sudden. Not impossible to work with, but needs some improvement. I need to drain what I put in and get some 60w gear oil. Though no one responded to my question about the gear oil the 4 times I asked...

The other "issue" was it wanted to stall under heavy load which required I re-choke and restart the bike. So something is off in the tuning for sure. Not sure what.

IF anyone has any thoughts or experience with the stage I am in I would appreciate advice.

Thanks,

MG

Hello. The right timing is 22.15 degree before TDC.
And about the clutch:
Due to the long time of "sleep" the clutch plates might be "glued" together. In such a case I drive with cltuch lever pulled and often, after some minutes, the clutch plates begin to separate.
And about the oil.
Modern additives in oil lead to clutch failure in the MZ clutch. These additives make the clutch plates loose the connection between the plates, so the engine will idle up without accelating the bike.

In Germany we use an oil with very little additives.Here we call it GL3 gearbox oil.And the viscosity is GL80.
Don´t use motor oil(additives!).

Puffs and Guesi,

There are so many factors in play here that whatever problems I am facing at the end of the day that then I get more information on the next evening when I have some time with the bike that totally changes how you might advise me does 2 things. One it makes me appreciate good folks like you who are here to provide support and advice, and two makes me with I just kept trying on my own because some of these things work out and it is a bit like crying wolf when that happens.

At any rate, here is my update today.

I definitely had the wrong trans oil in and I put in my special cocktail of what I had available which was some Red Line MT90 and about 20% Brad Penn 30w Engine Break in oil. The Brad Penn oil is super high in Zinc and has helped me bring some other faulty transmissions back to life. It added some needed slip, but not too much. All good there for now. I ordered a quart of 60W oil for the trans but need to digest that last post before I make my next move there. Thanks for all that good information.

The stalling was the bit that I quickly discovered in this evenings session was related to the petcock being clogged. It was fuel starvation. I have temporarily solved the issue by taking the petcock off and cleaning it out. The bladder rubber under the valve was the final bit that needed some love in the short run, but I this weekend I need to clean out the tank better and I probably will be served well by replacing the petcock. Like I said earlier in the thread, ALL the rubber on this bike is in bad shape. Once I restored fuel flow the bike was running nice.

Took it for a ride down the street and SHEEPGAWDVANDAMM this bike is more than I had imagined. It has good torque and was gettin down the road just right. I am impressed no doubt. Looking forward to a real ride.

Now for the next issue. There is a bit of a concerning knock coming from the engine upon letting up on the throttle after both quick revs and even after a more smooth high rev. It literally sounds like a mechanical clunk coming from the crank case. I was hoping it was a matter of the too thin trans oil I had in there before, but after I put the good stuff in, it still seems to be happening. Not sure what I would check next, by the sound of it it seems it could be anything from the crank bearing to some other shaft in the drive line that has play in it.

Putting that out there again to the pros with the thought that some of these things are typical to this bike.

All in all in just 5 days the bike has gone from mothballs to pissing off my neighbors with me ripping around my neighborhood. All good. I just don't want to take the thing on a real ride until I know that knocking isnt going to seize the engine and throw me at 65MPH on a highway...

Thanks again,

MG

Thanks Puffs.

Thankfully there was an inline filter there. Seems good for now, but I am going to order a new petcock anyhow.

Good advice on the knocking. I'll order a gasket set and then pull the head and barrel. I can then check for some wiggle in the rod.

Keep you posted.

I got an MZ with an extremely rusty inside. I was forever unclogging the tap (would clog up reserve ) and also had a filter too. Even after I thoroughly washed it through. After about a year, with a new tap too, all the floating rust has gone