Are Suzuki GSX250 and GS250 engines the same?

[Johnny]

I've got a GSX250 EX (1981) for which I plan to buy new pistons and maybe some other parts too. There's this piston kit on Ebay: http://www.ebay.com/itm/Piston-Kit-fits-Suzuki-GS-250-TX-4T-Twin-1981-/360890967555?pt=UK_Motorcycle_Parts_13&hash=item5406c72603&vxp=mtr, which is listed for GS250 TX (1981), is it the same thing engine wise? There are several different models of these GSs and GSXs (GS250 T etc.) which definitely have a similar engine, but are they excatly the same?

 

[hillsy]

There are 2 types of GS / GSX engine - 2 valve and 4 valve (per cylinder). The confusion is that in the US they were both called GS, whereas in other markets, the 4 valve model was a GSX and the 2 valve the GS.

Looking at the cam end caps, the 4 valve engine had square covers, whilst the 2 valve engine had round covers.

All the 2 valve engines were the same and all the 4 valve engines were the same, but you can't swap a lot of 4 valve engine parts into a 2 valve (and vice versa). Especially pistons because the valve reliefs will be wrong.