This came to me with a couple of other unidentified pistons.

As the bore is 56mm plus the oversize, does anyone recognise it as being for one of the DT125 models?

As well as Yamaha being stamped on the inside, there is Izumi underneath the digit 3 - is this an original Yamaha item?

Some photos are attached.

Thanks as always folks.

Alan

It's from either an RX125 or an RS125 Yam. RS is very slightly raised top & RX it flat top. Rs runs a squish type head & are a 4 speed box [in NZ] & the RS i had a lot to do with had good torque & revved to the moon. RX had no squish just a dome head & were revvy with a lot less torque. We sold both at work . Anyhoo--the piston you have is about 5mm taller than your normal 125 piston & by memory the cylinder is that much taller & the ports stretched out more. I have a 0.75 RS piston for sale on trademe to compare. Hope i've not confused things too much but just compare pics of what you require & pic you have & study the height. They did the same thing with our AG100's from 1980 when the grasshopper [assgroper we called it lol] came out which confused people buying piston kits for earlier Agy's.
www.trademe.co.nz/Browse/Listing.aspx?id=2561608222

Writing changes style halfway down looking from my end. Not sure why or if it shows to you but damn annoying. how's the weather up there, [flooding], I watch a bit of free tv from UK on internet & wife has relle's in Wales, & we have friends in Hereford.

Thanks RT.

I'll have to research if we got the RX125 here in the UK, or the equivalent model. Piston is definitely flatter topped than I've seen before and it is also quite tall.

Weather here is quite depressing, but not life, home or business threatening like some that I've seen. We're near Salisbury, on chalk and also relatively high ground.

I had to laugh when I saw that our lady cricketers had been knocked out of the tournament in Oz because of heavy rain at the venue in Sydney!

Thanks again and all the best.

Alan