I didn't take it off... it came with the bike. i already have a cylinder on it. altho i have nooo idea where teh hell that one came from either.the port timing is probably improved over the TRX topend. if it ran good when you took it off, i would leave it on.
You see, thats what the deal is with the Pro-x jugs, Allen at CT Racing designed them, did all the R&D & used the good points from other cylinders combined into one cylinder for the best output.i have my 89 cr250r apart right now... the jug looks stock other than the transfers runing out the top of the reed cage area..... that must be newer jug or something.... everything else looks the same .... except those transfers.... thats so weird... cause that looks like a snap from inside one of these modern pro-x jugs or something , my 89 jug looks almost identical to a 86 trx cylinder ... besides the PV stuff