Does anyone know of a post /publication that summarizes the available sizes of pistons (standard bore through known over sizes) for the various Enduro models?
In my case specifically, I'll need info. on both AT2 and CT2.
I'll be needing to have these bored and seems to me that I should provide this info. to the machine shop so it can be determined what size to bore too and the piston(s) I'll need.
It's not like they can walk into the stock room and pull them off the shelf anymore.

Pete

The official Yamaha parts manual should show what oversizes were available as standard and what the part numbers are. Yamaha usually went in 0.25mm increments, up to a max of 1mm oversize. Companies such as Wiseco do their own oversizes, but I don't know sufficient to comment on these.

A good machine shop should be able to tell you how much you need to take out of the bore and you can then add this to the current size to see what new size is needed. My understanding is that the machine shop will need the piston when they do the re-bore and they must also be familiar with Yamaha cylinders. Others will confirm the specifics on this.

"they must also be familiar with Yamaha cylinders..."

This is the part that concerns me. The fellow I've depended on for a number of years now is no longer doing them. So, I figured the next best thing was to bring documentation to a reputable machine shop and that measurements are measurements, math is math

Don't quote me without proof in writing you can take to your machine shop--but--i think they said 0.045mm "about 1.6 thou" measured 18mm up from the base of the piston.. Never sure why they say that but think it stays the same from there down on the shirt of a new piston.

I recall reading that the port(s) might need a little chamfering. HOWEVER, please search the forum, or wait for someone else to post, for confirmation. In my case. a little knowledge and a very dodgy memory is a very dangerous combination!

This is what I was able to put together which should be sufficient.
Being that it's pdf I was unable to edit out all the extraneous information so I simply highlighted what will be needed.
I have an old BSA and in one of the factory publications they listed all this info. by model in one easy to read chart. That's what I was hoping to find.

That would be a little like taking an old Model T and the manual/specs to a repair shop that specializes in new fuel injected turbo cars. You'd be lucky if they got the Model T to run at all and even luckier if they didn't mess up a bunch of stuff a shop that knows Model T's wouldn't have any issue with.

I'd rethink that and use a shop familiar with boring and honing air-cooled two strokes including restoring port chamfers.... AND will pay attention to factory clearance recommendations.

Mail it off to Bill Bune or someone and just get it done right. An AT or CT cylinder will fit into a USPS medium box so not a huge expense to mail. Send the cylinder there... they will tell you what over size piston you need... Have Enduronut ship the piston/rings to the shop... wait for it to come back in the mail... and done.