i ported this out to match the intake ports and skirts to match the transfer area of the jug. it was a 66.5mm bore that was on its third piston in the same bore. i purchased that now destroyed wiseco at a very good discount under the assumption that it was the next size over. I assembled it and did the warm up for 10 to 20 minutes at a time at least 8 times before riding it. it had low compression from the get go.Even though it ran very well i knew it was low on compression and needed bored. i even used xado directly on the cylinder hoping the rings would seat better. while riding it after warming it up it made an awful racket and i shut it off quickly. i then put it in neutral and kicked it slowly. I immediately knew it was the skirt by the sound of it. then i said screw it and turned on the spark it fired up and sounded like something was rattling in the exhaust. th exhaust eventually quit rattling and the bike still ran pretty fast. today i tore it apart to check my port timing and replace the piston with a larger one and lone behold a trashed piston. I've ran 2 of my port jobs with wonderful success this is the only one that had a wore bore. The ultimate question was it the loose bore, hogged out piston or both? Thanx you guys rock !!!!
