Yeah, Tony, like you say way back years ago, but far back as I can remember, even before the R riders site days & when I was a new Mac Dizzy member, there were maybe 4~5 people even had 250Rs with short rod cranks.
Way back to my first day on Mac Dizzy, even before that, say like the late 80s, the hot set up on the 250R was the 85/86 crank webs pressed apart & 87 to 89 rod kit pressed in, so even that far back most all 250Rs had the long rod, at least the racing ones.
There must have been something about the aftermarket cylinder castings, the reason for them being machined on the base so much.
Now you take an OEM Honda 250R cylinder, either year model & using it with a long rod crank & 85/86 style piston, you'll need a 3mm spacer plate for it to work, but you take a Pro-x or ESR cylinder with long rod & piston the same style as the 85/86 & you'll need a 4.8mm spacer plate.
The short rod was something fazed out years ago, but cylinders have not followed along with that & its hard to figure out why not, unless theres a need just to sell spacer plates.
Figure this one out, quite a few years ago had a guy was wanting a 265 Pro-x & we couldnt find a used one anywhere, so I talked to Allen at CT & he said maybe, but he would have to see if he could dig his old molds out from in the shop to cast one. I was thinking & asked, should I just contact LA Sleeve since that is where the Pro-x comes from anyways & he said LA hadnt cast one in years.
I was thinking the Pro-x 250~265 & the 310 casting was the same, but he said they were not & that there were 8 different cylinder casting for the Pro-x cylinders between the PV & non PV cylinders.
Kinda funny how it has all turned out, finding out that info & then knowing Calvin did the first Pro-x cylinders.
Neil
