Ts250/1 barrel swap with ts250

[DAVIDGUEST123]

I don't know if anyone has tried this but what I'm trying to do is swap a supa 5 250 barrel with a ts250 barrel. Long story short ,seized,(see previous posts) rebore wrong size, piston slap, barrel has fins broken, good ts250 barrel bought(also one size oversize) hoping the two are interchangeable..here is what I've discovered.

Both barrels have the same casting number

Ts 250 barrel at the to[p has no lip

250/1 has a lip at the top

Basically the differences that I can see is..
1)The bore sizes. Both barrels are one size oversized yet when measuring the bore with and old standard size ring the 250/1 gap is around 2mm and the ts250 is 0.5mm. Even with my rudimently grasp
of maths that doesn't seem right.
2) The lip at the top of the barrel where it meets the head. 250/1has a square casting and a lip but the ts250 is round with no lip.
3) There is a small 'H' stamped under the exhaust outlet were as on the ts250 it's a 'M'

So the big question is ..If I take this ts250 barrel and get it rebored(to the correct 0.04mm clearance) and stick it on my 250/1 Supa five will it work?

As ever many thanks in adavnce.
Dave

[Puffs]

Thanks for those pics!

Right, I learn that when they went from the 4-speed TS250 to the 5-speed TS250/1, that lip was introduced. I had not noticed that lip on your earlier pics, and just reminding you that I never saw any of those barrels in-the-flesh. However, that lip is also there in the later ETZ's, which followed the 5-speed TS. It probably helps sealing, but I don't think it is essential: when boring a 250 barrel to 300, as some do, that lip is lost. However, it will probably require a different head... Either to accommodate the lip, or to compensate different heights - you should measure the heights & distances as indicated in viewtopic.php?f=20&t=10396&sid=a1e9473259d5d867a7cb99b1e9f93366#p51000. I suspect that the port heights from the top of the lip will be the same as those from the top of the barrel (sleeve) in the 4-speed one.

For clarity, I assume you previously had the 4-speed TS250 barrel, without the lip, and that the one you bought was the 5-speed TS250/1 barrel, with the lip. Please correct me if I have this wrong. Your bike is a '78 TS250/1, = the 5-speed one, so it had the barrel from the previous model on it. And maybe with a head matching that barrel, maybe with the original TS250/1 head (in which case the compression ration will have been way too low!).

On your observations:
1) I think the standard bore & stroke were not changed, and are still the same in the ETZ: 69.00mm & 65.00mm. Now 1.5mm difference in circumference means 1.5/pi difference in diameter, which is 0.5mm. So they are not both at the same oversize, the 250/1 is one size bigger.
2) The lip needs to fit inside the head. At TDC, the piston will probably be at exactly the same height from the top of the lip in the TS250/1, as it is from the top of the TS250 barrel. But you need to verify that. If that is so, you might still use a TS250 head on the TS250/1 barrel, but it requires a ring around the lip, to correct the compression & the height of the barrel. A bit like this one:

Compression ring.jpg (21.86 KiB) Viewed 8 times

but then with the thickness of the lip's height. But as your bike is a 5-speed one, you might actually already have the correct head? We don't know what your predecessor did, have a look. At any rate, you should measure the gap (page 30 of the manual):

Gap in TS250.jpg (30.73 KiB) Viewed 8 times

3) Haven't a clue.

On your question: I think you bought the barrel that belongs to your bike, but you previously had an older model barrel on it. Yet to fit it, you may have a problem with your head - see above.

[Guesi]

Hello

The TS 4 gear and 5 gear cylinders are interchangeable.

But the one without lip is not an TS 250 4 gear but an ES/2 cylinder.
The lip was to center the cylinderhead in relation to the cylinder

The ES cylinderhead was centered by the long cylinderhead screws.
So there was no need for a lip.
The TS 250 models had another cylinderhead with smaller holes for the Stud bolt for cylinder fastening. The head also had the function to hold the engine in the frame.

So your cylinder without lip is NOT interchangeable. It is an ES/2 cylinder.
As the mould for the cylinder is the same on both models, the spare part numbers are the same.

That is why I asked for a picture of the intake side.
You can see on the right cylinder on the picture above that there is a sprue on the left side where the intake is.
This is because on the ES models there was a cover for the carburetor. And this cover should touch the cylinder where the sprue is.

[Puffs]

Ta for clarifying that Guesi, and correcting me - it helps if you know all these different details, and have seen those barrels...

Yes, I see what you mean, there is a straight protrusion on the RH barrel in

barrels mz.jpg (43.87 KiB) Viewed 8 times

which could fit a cover over the carb, as the ES had & the TS not.

Indeed, a major difference between the ES & the TS is that the engine in the TS (as in the later ETZ) is fixated in the frame via the head. That will enhance the need for a positive fixation barrel<>head, hence the ridge/lip on the barrel. As you have a TS frame, you will have a TS head, so you should be good to go (after a rebore?).

[DAVIDGUEST123]

Thanks for all the input chaps.

Just to be clear.The old barrel with a broken fin from the bike which is a TS 250/1 Supa 5 from 1982, the barrel I was hoping to get rebored and fit to it now turns out to be an es250 barrel.

1972 Es250 barrelwith the carb shroud supports shown

and these to barrels cannot be swapped

1982 TS250/1 Supa 5 Barrel from the bike

I also think that although the barrel has been stamped as if it was one it's first rebore it is in fact standard

Looks like it's back to the drawing board for now.

Many thanks Dave

[Puffs]

Apologies for being so persistent, particularly if I see it all wrong, as this is all mighty confusing Dave, but I don't quite see why it should be 'back to the drawing board'. The '82 TS/1 you bought had erroneously been fitted with an ES cylinder, which developed a problem, and then you bought a proper (although somewhat tarnished) TS barrel on eBay. Right?

I think the captions are confusing, they should read:

Es250 barrel, with the carb shroud supports shown, and without the ridge to fit inside the head. Was found on the 1982 TS250/1 Supa 5 when bought.

es250.jpg (30.97 KiB) Viewed 8 times

and

TS250 barrel as bought on eBay, with the ridge/lip, should fit the bike fine (after clean-up & a ?rebore?).

TS250Supa5.jpg (35.82 KiB) Viewed 8 times

Looking at the pics from the eBay advert, that barrel should have plenty of meat left in it, and it might indeed still be at the original bore. If it's one of the smaller sizes (69.00 or less, marked 0 or -1), maybe just some honing would be sufficient to remove the rust & you could get away with using an 68.97 or 68.98 piston.
Barrels are not normally marked after a rebore.

[DAVIDGUEST123]

this is the barrel orginally on the bike note the damage in blue

Above is the one incorrectly rebored form the bike

ES250 (so I'm told) bought from ebay

This is the one that will not fit, due to fitting of the head bolts..shame

[Puffs]

OK, ta for clarifying.

Our "Do older ts barrels fit supa 5" PM was concluded by you telling me that you would purchase the barrel from https://www.ebay.co.uk/itm/MZ-TS-250-CY ... 7675.l2557, which is very much like the TS barrel in the top picture, with the lip. But apparently you bought another one. And indeed, already in your very first thread there is a pic of your TS barrel.

My apologies.

[DAVIDGUEST123]

Hi .
Yep I'm now sure that the nice es250 I bought (not the one in the eaby add), although it looks very much like a ts250 barrel apart from the carb shroud supports. It will not fit
my bike. This comes down mainly to the mating up of the head. The conculsion is that although port and barrel positions are indentical the lip at the top serves two purposes
One being the easy locating of the head but also to help support the engine without moving as the ts motor is 'Hung' from the frame by it's head. Were as the ES is supported
in the frame.
Had I gone ahead and fitted the ES barrel I'm pretty sure it would have run. I would of however have had possible problems with the join betwwen the head and the barrel and as I'm planning a
long old trip this summer everything needs to be right.......at least beore I set off.