Piston choice for ts250/1

[DAVIDGUEST123]

Hi all.
I'm now at the point where I need to rebore a very tidy barrel purchased from ebay. The old one I had rebored to 3thou(iknow too big) had fins broken, so it's a bit of start from stratch. I have the barrel, I now know what size to do rebore it, all I need is a piston. 70.00mm for a second oversize will be the size, but I'm unsure where to buy from and which one (Almot K20) It all a bit confusing. This time I want it to be right. Thanks Dave

[Guesi]

There are original GDR pistons available.

https://www.guesi-motorradteile.de/inde ... 9/c/_/_/?_

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[DAVIDGUEST123]

Hi again,
Wel lI've pulled the barrel off and it seems to be very different from the ebay one. I suspect I have an old ts250 rather than the 250/1. Question is will it fit. Although it has been rebored once the diameter is very different from the orginal, as shown in the pictures. It's a real shame as the 'new' one is in far better condition. As ever any infomation wil lbe greatly recived.
Many thanks Dave

[Guesi]

Which one is the new one ?

Can you post pictures of the intake side ?

And how is the diameter of both ?

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[Guesi]

They both can be rebored as long as it is not already on its last oversize.

[Blurredman]

I do have a spare piston.. Used for only 50 miles. It was for an ETZ250 however..

I think it's 71 mm actually..

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[Kruh]

Would 0.05 mm clearence be to little for an Almot piston?
It would probably require a more careful/longer break in process.

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[Blurredman]

Regardless, running-in should be done very carefully, and it's probably wise to have a look after, say, 500 miles. Not sure if the manual says something about that. Personally I like to mix richer during running-in, but I know the manual does not suggest that.

Yes it does. Though it doesn't explicitly mean oil. But more fuel = lower temp.

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[dave47]

I am about to run in a TS125 with an Almot K20 piston, and have had the cylinder bored +0.03mm as per the MZ manual but now I'm starting to worry that this may be too little! Anyway its done now, and I will just need to be careful.

My real concern is what sort of 2T should I use? My instinct was to use the best quality, but I have read somewhere that modern fully synthetic oils are so efficient that the engine never runs in. So perhaps old fashioned mineral oil is best. Does anyone have an opinion?

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Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.