John, I'm sure you can get them rebuilt. I don't know if you can use AS3 crank but I would not expect so. Don't know about rod kits but I'm sure they are available if you do a google search. There are still parts available. As a start have a look at http://www.cmsnl.com/yamaha-ta125_model11331/partslist/
Hi. Have a look at your engine serial number. they originated from the AS-1 and the AS-3 . The only thing you will have trouble with is getting a labyrinth seal. They don't make them any more.
yours Graeme L.
Try here. http://www.ebay.co.uk/itm/Yamaha-Labyrinth-Seals-Genuine-Part-132-11515-01-YL1-AS2-HS1-LS2-RD125-TA-/321033447210?lgeo=1&clk_rvr_id=423966594040&vectorid=229508 at 25 pounds. They have 6 available.
Hi Lindsay . Many many thanks for that information. They say they wont send it to Australia I've got their phone No I will try to ring them tonight.
Yours Graeme L