I have read a few posts regarding the possible problems that can occur with the stock piston. The previous owner never changed it.
So I will change it soon for a Wiseco piston.
My question is: Since it's winter now. Outside temperature is about 10F (-12C). Does a cold temperature can have bad impact on the breakin???
Only the jetting, which make it leaner as it gets colder. Just richen up the jetting for cold weather riding and let the bike warm up real good before you get on it very hard and you'll be fine. Be sure to break that wiseco in properly and you'll be fine. Proper break in requires a few heat/cool cycles and then a few short 15-30 minute rides with an easy load followed by a good cool down.