2 Cycle Sleeve Machining

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Scra99tch

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While pulling apart my 1957 T.W.N. (German Triumph) Super Tessy engine that was frozen I damage the cylinder beyond what I think I could bore it out to. So now I am thinking about farming out the sleeve to be machined. But.... If I were to attempt the build what would be the best way to fixture the sleeve so that I could cut, what I believe are exhaust port bevels.

I can post a picture later today.

There was a neat way of mapping out the ports by way of paper and charcol imprints. Then measuring the height, width and location of the ports.

It almost looks like most of the bevels are die ground away on newer builds. I was hoping I could try out my tilting dividing head on my mill, that might over complicate things
 
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You will probably need to build any fixtures needed yourself since it’s unlikely you’ll find a shop tooled up to do the job.

Is there an internet group dedicated to this bike? Your best bet is finding another cylinder, failing that it might be advisable to learn how to do this yourself.

There are lots of model engine guys on here who build stuff from scratch who will likely be able to help.

John
 
matthewsx said:
You will probably need to build any fixtures needed yourself since it’s unlikely you’ll find a shop tooled up to do the job.

Is there an internet group dedicated to this bike? Your best bet is finding another cylinder, failing that it might be advisable to learn how to do this yourself.

There are lots of model engine guys on here who build stuff from scratch who will likely be able to help.

John
Click to expand...
These are fairly rare and I cannot seem to find many stateside let alone, in Germany where they were built. Ugly little buggers but look nice when done up correctly.

www.bonhams.com

Bonhams : 1957 TWN 141cc Tessy Super Frame no. 591342 Engine no. 591342

Founded by two expatriate Germans – Siegfried Bettman and Maurice Schultz – in Coventry, England in 1897, Triumph began making motorcycles in 1903 and opened a second factory in Nürnberg, Germany. In 1929 the two companies split, the German one becoming Triumph Werke Nurnberg (TWN) and Triumph...
www.bonhams.com www.bonhams.com
 
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1684850908138.png

Not mine, its a bit more crusty but complete.

Was browsing facebook and a local offered page was offering it. I happened to be the first to reply and they gave it to me. Guy collected cars.

Turns out it happened to be brought down to the transfer station in 96' and the guy at the station called his friend to come pick it up. It had a US military sticker on it from someones unit while he was stationed in Italy. He brought it back here and it was last registered I believe in 81'.

Been sitting since.

I am doing full restoration on engine and then possibly leaving everything else as is. Maybe getting to the paint and chrome bits as funds permit.
 
Interesting.

Since the engine is completely covered you could (if you wanted) change up the power train and still appear original.

I’d be inclined to switch over to electric power and be done with it, but that’s me….

I have no idea what these things are worth in original condition, or how you feel about resto-mod vs. original. But for me, I’d be inclined to get it on the road with as little fuss as possible. If you don’t make any structural mods it can always be put back to stock.

On the other hand, you might really want to learn about resleeving 2 strokes. I’ve done lots of small engines so there’s no mystery there for me.

John
 
The aluminum castings on the engine are pretty intricate on how they directed the flow across the fins by way of the generator turbine. It'll get up to 75 miles per hour. So I would like to work on the engine and keep the rest as is for now. I have a feeling or I had read there are probably close to 10-30 of these pieces still in existance worldwide. Not sure about that as there is very little info on them out there.
 
Because of the precision requirements of a piston bore, I'd consider getting a custom or near-fit sleeve on order from a manufacturer. It's just a single piston. Custom sleeves for multicylinder car engines aren't prohibitively expensive, so a one-off should be reasonable. Last time I looked at custom sleeves I was looking at $150 a pop, not bad considering the added reliability of a part made right. I don't think I could do justice to a bore job on my mill, it's a job for a cylinder hone. Dropping the stripped block and a new piston off at a speed shop will ensure a good seal, straight walls, the right finish, and a square deck. It would be a fun DIY for a junker Japanese bike, but you are holding a rare gem. Farming out the critical task might be the best for your project.
 
Just make sure it’s the right shop. Snowmobile guys are used to strange stuff as are guys who work on vintage bikes.

Ask for references!

John
 
Check with Weisco for custom pistons. They may have a lead on cylinder sleeves as well. Vintage racing kart guys may be able to point you in the right direction too.

Let me know if you want some leads and I’ll dig through my old contacts.

John
 
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