Hey no problem. I'm old and forgetful myself. 

Thanks, I had a hard time finding the correct piston. I ordered one from Ebay that was listed for a DT125H and installed it. Once I got it together I spun it over and it clunked and hit the head.  Turns out the wrist pin location is different for the 2A6-11631 piston. Anyway I found the correct piston from a vendor in Poland.. Thanks for your reply and help.

I too rode BSA's for 26 years. I owned many a 441, 500, 650 models. Then one day I bought a Yamaha XS650.....the electrics worked all the time...it did not leak oil and gave a good massage as the BSA,s. I sold my BSA inventory and still ride a 1977 XS650. 

Thanks. 

This site does not like ebay links, which is a bit of a pain when you come across a rare and obscure part, but look up..

eBay item number:403946204335

I just copy the url.

403946204335 for sale | eBay

The problem is the old site software is designed to embed ebay links...  you used to get a nice little "preview" shot of the auction listing like YouTube links give you here.

The software still works as designed.  The issue is Ebay decided to block "hot linking" a few years ago...  So the FAIL is that ebay won't allow the link to call up a preview (Like YouTube links still do).  

Apparently that "embed" function cannot be turned off in the software so challenges like this and other would require a complete rebuild of the website with new software...  potentially a major undertaking.