MZ TS250 (1974) - First day Running issues

[neomuzzi]

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!

[Puffs]

Hi neomuzzi,

$1250 for a '74 TS250 with just 1750 mi, that was well prepared for & stored dry in CA, that sounds like a good deal!

Suggest not to use files in a carb. If required passages can be cleaned with a strand of steel wire and (preferably) compressed air.

I don't know for the TS, but for the 250cc ETZs a B7HS (or equivalent) is prescribed. A 9 seems cold for such a bike, but more importantly: try a plug without a resistor, particularly if the cap may have a resistor in it.

Clean the breaker contacts with a suitable fine file, or some sandpaper (grit 240 - 400). Then adjust them to the values specified. (If you know nothing better, try 0.35mm lift height & starting to open @ 2.7mm BTDC, but no doubt someone here will know the right values for this bike.) This bike requires a well charged battery for the ignition to work. Before you put the plug in, check for a spark. And with fresh pre-mixed fuel it should then work.

About the rubber: I'm not sure if that is very common. My bike is 15 years younger, but the rubbers are still fine (except for wear). The chain gaiters & cover serve the purpose of protecting the chain from water, mud & dust, and with those the chain & sprockets last a long time. But you can take them off, if so desired (speedo cable may be in the chain cover).

As part of the recommissioning you should probably also lube the chain & all cables.

[neomuzzi]

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

[neomuzzi]

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!

[rightsideup]

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.

[Puffs]

You set the crank in the position where the lift is highest, and then you adjust the lift height to the value prescribed, measured with a feeler gauge. Timing is set by rotating the base plate. Assess when it lifts by pulling the connection to the breaker & use a beeping Ohmmeter, or just rig a light in parallel. Measure piston position with a dial gauge or so (if the plug hole points straight down). You can also rig a measuring device from an old plug & a piece of known thread inside.

Maybe best download a user manual or Haynes manual for it.

[neomuzzi]

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.

[Puffs]

See page 54 in the TS250 manual from Blurredman's website, but I must say they turned it into quite a complicated story.

And I see you cannot easily measure the piston position through the spark plug hole, so best use a timing disk (21°BTDC, p. 9), and forget what I earlier. The bit about measuring the piston position with a rigged measuring device from an old plug & a piece of known thread inside won't work; that only works if the plug hole points straight down, and it doesn't in your bike. But even when the spark plug hole is oriented as it is here, you can still feel the piston in TDC with a small screwdriver or something else through the hole. For me that's good enough to find TDC & note it on the timing disk.

[neomuzzi]

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

[Guesi]

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]

Ah well, the "MZ_TS250-1977-Official_Service_Manual.pdf", where they specify "20° to 22° crank angles", of course pertains to a later year, and pre-ignition values have reduced over time, as fuels have improved. But frankly, anywhere in that range is good enough, you'll be hard pressed to sense small differences. (Btw, presumably 22.15 degree = 22°15' = 22.25°.)

If at some stage you'll feed the chain through the gaiters; make a hook in 2' of relatively sturdy wire to pull the chain through.

Clutch: as Guesi said, let it slip a bit & see if that improves it. Let it slip a bit, but not too much & not under full power: do not burn the clutch. If your clutch remains too direct, maybe the oil is too thin. I haven't a clue what oil I put in mine.

Fyi, the API (=American Petroleum Institute) classifies transmission oils (GL = gear lubricant) as follows:
GL 1 – without additives, for manual transmissions exposed to minor loads
GL 3 – mild additivation, EP-additives, can also be used in manual transmissions with non-ferrous metals, clutches running in oil bath
GL 4 – strong additivation, for manual transmissions, hypoid gears (if permitted)
GL 5 – strong additivation, for hypoid gears
This classification says nothing about the viscosity of the oil, only about the additives.

The viscosity is an indication for how easily the oil moves. For instance, when you pull the clutch, there will be a thin layer of oil between 2 adjacent plates. The engine runs & that oil is sheared between the plates, causing viscous forces: the higher the viscosity, the higher the drag. Then when you release the clutch, that oil is pressed out & only thereafter the plates make contact. A thinner oil (low SAE numbers) is pressed out more easily, and the clutch feels more direct & more grabby, and can handle more torque. For that & other reasons, racers & some MX bikes have a dry clutch. Similarly elsewhere, a thicker oil gives a thicker oil film which might give more lubrication, or more friction. It is therefore important to look at the viscosity.

For instance Addinol GL 80 has API classification GL 3, and SAE viscosity classification 80W. This oil previously had a commercial name of GL60, as prescribed in the manual, but I don't think it ever had an SAE viscosity of 60W. The 60W you mention seems a bit thin for a gearbox.

[neomuzzi]

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

[Puffs]

OK, so maybe I was too positive in thinking that this bike was well prepared for storage & stored dry in CA; I had forgotten the possibility of corrosion in the tank. Clean out the loose stuff in the tank as good as you can, and place an in-line fuel filter before the carb. And make sure the carb is clean, and that you have sufficient flow from the tank.

On the knock/clunk I cannot advise you. It could be many things. If you're really worried about it, best to take off the head & barrel, and inspect the piston, bore, small end, big end & main bearings, which you can then see and/or feel. This is not as much work as it might sound like, on a 2-stroke, but you will need some new gaskets. It is not inconceivable that the long wait has taken its toll, or that there was a reason why it was put aside 40+ years ago, after just 1750 miles. On the other hand, it might also be something harmless, or some feature of this particular engine (I do not know this specific engine); I cannot judge from here.

[neomuzzi]

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.

[Blurredman]

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