Quote:
Originally Posted by JohnWayne007
if i can remember correctly the original bore and stroke before was 67x65mm and was changed to 70mm, i think that the cylinder was the same as the original just bored out to 70mm, i could have just bored out the original cylinder but it would have had to been re sleeved due to it pretty much blowing up, he had taken it out for a ride and heard a big bang and the bike completely stopped, he ended up pushing it home. i tore into it and the piston was toast, cylinder walls were beyond repair and piston rings were melted into the piston. so i ordered the big bore kit and didn't think to take measurements, i will be splitting the case in the near future just to check the internal components and clean it up a bit, he wants the engine re painted so i will probably take it all apart sand blast it and give it a new finish so when i do i will be sure to take as many measurements as i can and post them for future references, i actually still have the old cylinder and piston laying around to compare the big bore kit too once i do.
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A 70mm bore and 65mm stroke becomes an honest 250cc, without rounding up (like most manufacturers do). I might grab a kit like that for a project I have in mind.
Please start a thread on your friend's CG, when you blow it apart for paint.