Mine won't do 83kph (52mph) downhill unless you pull the clutch and hang onto a passing truck!downhill doesn't count.
sleeved cylinders. it's easy enough to do if you have access to a lathe. supposedly you can get up to a 52mm bore out of a sleeved china girl cylinder but I imagine wall flex becomes an issue at that pointthe transfers are only too low if you are targeting a high RPM output. For normal street use they are OK after being made equal.
I didn't think the out of round cylinders could be fixed because of the thin plating. Can you describe your fix?