'84 250R stock bore size? Urgent!!

[Ckretintimidator]

Hey guys, could someone look at a manual and tell me what the stock bore size for an '84 250R is? I have an '81 CR250R that I'm working on for a buddy and his cylinder is wore out and I want to see if a spare '84 cylinder is the same. The '81 is 69mm.
Thanks in advance for the help.

Regards,
Josh WInter

[atc330r]

atc stock bore is 70.0mm. check the pipe at cyl. atc come straight out and it seems like a cr is on an angle??????

[Ckretintimidator]

I'm pretty sure the CR pipe comes straight out, but I'll check. Anyhow here's what I found out when I went to a bike shop on my lunch break.
The cylinder bore on the '80 Cr is 70mmx66mm stroke(stroke could be off a bit), but it's chrome plated and non-boreable, unless it has been sleeved.
The bore on the early ATC250R's is the same, but they are not chrome plated so they can be bored out, and the clyinders are interchangeable.
I ended up honing mine alot and it ended up being useable so I'm going with that, but next time it wears out, I'm switching over to an ATC cylinder, if the exhaust matches up, like you said.
Thanks for the help.

Regards,
JW