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Hi all, I've got an original Casa SS225 reed valve cylinder kit that has had a severe seize. The Cylinder is numbered: 24111604, and the piston is 16-09-25336 and is also stamped 'A' I assume that's the measurement grade? I'm having the cylinder re-plated by Langcourt engineering in Weston-Super-Mare, but they require a new piston to be sent with the cylinder. Do I just order another 'A' grade piston from the supplier (Rimini Lambretta Centre)?

My other choice of piston is height- I can't remember which is best, 30 or 39mm? I haven't bought a crank yet for this engine so I can go with either a short or a long con rod depending on which is best- I'm trying to get as much cc out of this kit without machining the case, but it's been a while since I've done one of these and I can't remember the advantages or disadvantages of a long or short con rod. Any ideas please? Many thanks in advance.

doesnt matter weather you get A,B,C size piston as they will hone the replate to suit.as for 30 or 39 crown height someone with more knowledge than me will put you right on best option.

a crank with a 116 rod will allow you to use the 30mm piston. the longer should produce a smoother ride with a bit more torque lower down......or so i'm led to believe

what caused the seizure.

Ok, cheers for the replies chaps. Don’t know what happened re the seizure, I bought it as a bit of a punt off eBay. I gather though that a lot of the early SS225’s had problems with heat seizures, which is why Casa redesigned the piston? I suppose the lighter the piston the better so I’d probably go for the 30mm version and use a longer rod. If I couple it to a 60mm crank presumably I’ll get a final cc of 230? Can a 62mm crank be used without machining?

If you're after the most cc out of the kit why not go for an oversize? It won't be much work as you already require a replate.

http://www.afrayspeed.co.uk/index.php?p ... buteID=P25

With 60mm crank that would give you a 245. I would imagine wosser would be as good as any casa piston. 30mm crown height would allow for the benefits of the 116 rod.

I've just fitted a SIP crank to my build and seems a nice but if kit. Look good value if after the 116 rod.

Chances are that a 'Japanese motorcycle' piston could be made to function, though you may have to add reed valve port(s) on the inlet side.

Whatever you select, make sure that the rings are compatible with the bore material

Like the look of the Wossner piston but is 72mm going to leave the cylinder wall very thin?

Pompeydave wrote:Hi all, I've got an original Casa SS225 reed valve cylinder kit that has had a severe seize. The Cylinder is numbered: 24111604, and the piston is 16-09-25336 and is also stamped 'A' I assume that's the measurement grade? I'm having the cylinder re-plated by Langcourt engineering in Weston-Super-Mare, but they require a new piston to be sent with the cylinder. Do I just order another 'A' grade piston from the supplier (Rimini Lambretta Centre)?

Thats the best bet,then Langcourts can repair the damage,replate your cylinder and bore it to the correct size.

Pompeydave wrote:Like the look of the Wossner piston but is 72mm going to leave the cylinder wall very thin?

It might leave the skirt very thin, but this is where there is least heat. What you need to think about is how thick is the barrel "sleeve" between the fins. The standard Lambretta barrel was very thin here, hence all the work that AF used to have to do to manufacture their own 250 barrels back in the day. However, they were modifying standard barrels that were manufactured with the minimum of metal in the original casting. The Casa item is probably not manufactured to the same stringent attention to "cheap-as-possible" of Innocenti's mass produced items.

If you get your callipers out and measure the external diameter of the Casa casting between the fins, you might be pleasantly surprised.

Add to this the superior heat transfer found on Nicasil barrels when compared to cast iron, the fear of going for such a big bore may diminish.

You may already have too many options, but good luck.