Continuation - 1974 TS 250 - More riding-Need tuning advice

[neomuzzi]

Hi.

Finally decided to take the MZ TS250 out for a longer than a 2-3 mile cruise around the neighborhood. The knocking issue has not been solved, but so far it doesn't seem critical. At least not at the moment.

I went on a 20 mile or so ride in the back roads / hills of the area I live in and I have to say this bike is quite fun to ride. It was super stable and though I am not one for the riding position, it was a very enjoyable ride. Big power gap from 2nd to 3rd given probably too large a gap in gearing.

I definitely could use a bit of performance tuning. I don't have a tach, but this bike seems to run out of steam and need to be shifted at a pretty low RPM. Seems like the powerband is more low end torquey, but there has to be room for more.

Wondering if there are some standard mods. Pipe, ignition timing, new or ported barrel? Are there low hanging fruit or is it simply not worth it? I see a couple of cool MZ racing sites, so it seems some folks tune these bikes for performance. I did some searching on the forum but didn't find anything in the time I thought reasonable to search.

Thanks,

NM!

[parrbd]

Docoke the exhaust.

[neomuzzi]

Thanks. Will take a look. Bike only has 200 miles on it as far as I know. Almost feels like timing to me. The carb seems big enough to support more RPM, so exhaust it could be.

I see some cool looking expansion chamber type of exhausts, but I don't speeka duh German so hard to find one for sale. If anyone reading this knows of a place specifically to get performance related parts for the TS250, please do speak up.

My first thought was to go down a tooth or two on the front sprocket. But more HP would be a better solution.

thx.

[Blurredman]

Is the bike actually revving out, ??

Or is it just pinking, like- hitting a wall? Every gear? What speed are you able to get up to in top when this happens?

I would not bother with the expansion exhaust system. The MZ's have expansion chambers, they are just neatly packaged up in the silencer and from my experience and those of others, are not superior in any way to the original exhaust systems.

[Andy_C]

As suggested I would de coke the silencer, I would also check that the timing is set corectly, also check that yu have no exhaust leaks - in my experience a leaking exhaust system can make these bikes run badly.

Strongly advise against buying one of the expansion chambers unless you are any good with a welder - I bought one very cheaply just to try it.

As standard the chamber is way too short for the sort of revs that a standard MZ does, and it robs the engine of bottom end torque and pushes everything higher up the rev range giving you a very narrow power band.

I modified the chamber by cutting the chamber in 2 and welding in a long "belly" section, the pipe now performs as well as the standard pipe in my opinion - it just sounds a lot better, and the engine seems to rev a bit more freely and feels a bit livelier.

I'll post up a picture sometime.

[Andy_C]

Here is a pic of my ETZ with the modified chamber on it.

Basically a 11" section welded in between the cones of the readily available chamber that pops up everywhere.

Without the welded in section you only have useable power abouve about 5000 RPM with the belly section inserted power delivery feels pretty much like it does with the standard system.

I like it because it does make the bike feel livelier as well as making it look a bit different !

Modified chamber

[Puffs]

Looks good Andy!

Yes, there are rules to tune length (& volume) of the expansion chamber to the desired RPM range, and for racing they used a higher RPM range than normally desired for road use. So these expansion exhausts (which could be had very cheaply a while back) are not necessarily desirable on a normal road bike. Maybe a 250 exhaust on a 125, using an adapter on the header pipe, could work.

@neomuzzi: I wouldn't try to tune the bike for speed, as long as it still has the knock; what happened to that?

[neomuzzi]

Hey y'all. Coming back to this. Picking it back up essentially.

Went for a nice ride today after spending the last couple of days getting the bike to start easy and idle well.

Seems fine, but it also seems like the the electrical systems are weak such that unless the bike is warm and the battery is fully charged, it tends to want to stall due to misfires caused by lack of spark. Not exactly sure there, but it gets worse when a blinker is on or the headlight is on, so that is the clue I am working with.

Back to the power thing. The bike seems to make it to about 20 MPH in first gear, but then just holds there like it has some sort of governor on it. It just sort of maxes out. 2nd gear is near 37-38 MPH, but the same "run out of steam" behavior. I can keep the throttle wide open and it just drives along. If I shift, I am back on power, but assuming that 3rd would do the same once it reaches that same RPM range. Unfortunately I don't have a tach.

The bike has 200 original miles on it since 1974, so I doubt he pipe needs cleaning. Carb and Air filter are in great shape and recently cleaned.

Is that just the nature of the bike? Does the porting, exhaust, Carb, and airbox kind of give a hard limit to max RPM and power in each gear.

Thanks again!

[DAVID THOMPSON]

tired points spring
had a 72 750 bmw it had set for years like 18 it would run ok
but not much above 3000 rpm it was a dog
changed the points which changed out the spring and the point stopped floating

age had killed the spring tension so the points worked but floated at speed

[neomuzzi]

Dave,

That seems reasonable. It is a good possible explanation for why the bike is nice and torquey and accelerates nicely but then just stops accelerating and holds constant with so signs of stress. Shift and I'm back in the power...

Any preferred vendor for those parts? UK? Germany?

What is amazing about this bike is its stability and yet agility. It is like I feel more comfortable on it than on other bikes I have ridden like a Yamaha R3. In some ways the bike has an "on rails" feel.

Keep you posted.

Thanks,
MG

[Blurredman]

I've had 3 spark plugs go on my MZ's. And how do I know the telltale signs? The bike mis-fires and eventually dies with indicators and/or lights on.
Give it a try- Yes- I know it sounds silly..!


The electrics take quite a bit of power from the engine, you can feel the difference riding in the day compared to riding at night with the lights, I think..


Those speeds would seem to me to be pretty much end of the line for those given gears.. If the 5 speed bike maxes out at around 75-85, then I'm pretty sure a 4 speed would be the same- The fourth gear being pretty much an overdrive and only really of use on the motorway or dual carriageway. Top gear around town is best in third. You just won't have oomph enough to use 4th unless you're doing at least 45 and it's flat.

[Puffs]

Yes, try the plug - some bikes eat plugs, and always try the easy things first.

I have never personally experienced what Dave describes, but it is possible, and if that bike has been standing since 1974, new points are certainly worth an easy try. Has corrosion been an issue during that long wait? If so, what else might have been affected by the long wait?

A motorbike from 1974 with just 200 miles (or was it 1750???) does sound a little bit odd though, but of course if it has the original Pneumant tires (with the 'beard' still on), no wear on the brake shoe linings, or anywhere else for that matter, then it must be true. But then, that raises the question what the knock is, and what in the history of the bike has caused it? Does it still have that? Have you taken the barrel off & looked (viewtopic.php?f=5&t=9234&sid=2cfe52ecb26d5706bcd77dd1baed7f07#p47862)?

On the 'running out of steam' you describe: yes, that can be caused by a clogged muffler; maybe that option should not be discarded. If it did 1750 miles on engine oil in the fuel, 1:25, then it might be clogged. And you might also have carbon in the head.

[neomuzzi]

Thanks all. I'll investigate those areas.

This is the listing for the bike when I bought it.

https://www.mecum.com/lots/LJ0617-284074/1974-mz-ts250/

I read it as 174 miles. Am I wrong?

Thx!

[Puffs]

It sure looks like a nice bike, and I can also read that the counter shows 174 miles in one of those pics. But that does not necessarily mean that this bike has only done 174 miles. It only means that counter displays the number 174, which means THAT counter has PROBABLY registered just 174 miles (but even that is not certain). Please appreciate that a 45 year old bike may well have received a new counter, at some stage in it's life, for one reason or another.

From the pics it looks like a really nice bike, but 174 miles is brand new, and even from those pics I can see some signs of use (for instance on the shocks below the springs, and tool marks on the rear axle, which seems painted). Please don't get me wrong, the bike looks very nice, certainly for the price you paid, but 174miles is just a bit quick to loose the gear shift rubber.

Look at it another way: what would it take for a 45 YO bike to have done just 174 miles? When you buy a bike new, you want to ride it, right? OK, so the original buyer rides 100 miles, and then he suddenly gets a heart attack, after parking the bike neatly in his garage. And then ... well, etcetera.

Once again, the bike looks nice & I think you paid a fair price, even if the bike has done more miles and may actually need some work.

On the tuning advice you asked for: I would try to keep this bike completely standard. If you want fast, buy a fast bike.

[Andy_C]

I agree with Puffs - that is a really tidy bike.

Stick with it you will get it to run properly.