Here's a pic of a crank pusher & puller plus a flywheel puller just for a look. Better than my 50 year old damaged ones.Here's a pic of a crank pusher & puller plus a flywheel puller just for a look. Better than my 50 year old damaged ones.

Only thing there to be careful of is when pulling the crank in, that you might need to space the tool up a but as the crank will be fatter than the hole up the middle when it gets past the mag taper. Crank would be 25mm by memory but wouldn't have to lift the puller tool by much, maybe an inch.

Thank you RT and Pete. Getting replies from my cousins in the UK is like waking up Christmas morning to packages under the tree. Great advice and info. I was taking things apart and figuring out how they work since I was a kid so I'm certainly capable. I'll definitely be taking pics and using a lot of labeled Ziplock bags during this process. Hoping not to break anything as I dismantle it. If the crank is still good this should go fairly smoothly. I'll post the progress and hope to not need to upload too many annoying questions along the way. Thanks everyone for your suggestions.

Dropped the jug and head off at the machine shop. Great people who seem to specialize in motorcycle restoration customers. The piston was standard bore 65.75mm so he said I'll need a 66.50mm replacement. Not sure if the lingo means this is 1/2 over or what. They can move me along very quickly but they need the piston before they can start. As I said in an earlier post they do offer Wiseco pistons and could place the order in today. I'm thinking I should just pull the trigger and tell them to order the Wiseco given I have no clue how to locate an original. Partzilla doesn't show them as available and ebay seems like the wild west for things with critical clearances. Not concerned at this stage on cost. Is this a safe bet?

Did you try Enduronut for the piston?
2nd over from what you've said.

I tried to PM him yesterday but the CAPCHA verification box wouldn't check off. I also tried to contact him via the legends site but got a 404 error message. Unless using the Wiseco will be a critical judgement error I guess I'll go with it. 

I don't like the sound of piston slap
I like Yamaha pistons because they run tighter clearances than my limited experience with Weisco pistons
here's a 2nd oversize cheap!

65.75 is 10 thou under std 66mm. But lets not get into that as unlikely to be that loose. Cylinder must be 66 & worn & I guess they know what they're doing so must have decided they need to go to 66.5 which is two steps in yamaha pistons but one step in Wiseco. Doesn't take much to "Not' clean up at yamaha 10 thou steps if you can visibly see the wear.

I’d be a little worried about the machinists skill.  Standard bore was 66mm and often slightly bigger. No way it could be 65.75. 

if they measure it as accurately when boring, it will rattle like hell. 

spend a couple bucks and send it to bill bune or someone who knows these bikes. 

p.s. Enduronuts email is all over this site if you search. 

Thanks Mark. I'll reach out to him in the morning. This uncertainty was very much what I was afraid of. He didn't measure the bore...he measured the piston which I assumed would give him a sense of what piston to order. I did try email Enduronut but it only showed me the contact form and the email wouldn't send. Damn if I didn't go ahead and tell the shop to order the wiseco since they said they had to get the order in today. Maybe I can halt this process.