blaster2006 Posted January 11, 2009 Report Posted January 11, 2009 heya, quick question about cylinder boring, lets say i got a stock banshee cylinder, 64mm, and i want to get it bored, i take it to this mechanic place next door who claim they can bore cylinders. lets say that they inspect it and tell me it needs "0.20 over". now, in order to bore, you dont need a new sleeve right? i dont really know exactly how cylinders are, but when they bore, they "remove metal" and make a bigger hole on the current sleeve it has, then its good to go? all i need is a "0.20" over piston, correct? also, something else, how many more mm is each 0.10 over, so how much is 0.10 over in mm and 0.30 over lets say in mm? Quote
BlntdEyez Posted January 11, 2009 Report Posted January 11, 2009 well .10 over 64 mm is 64.25 mm .20 is 64.50 and so on and so on. All you need to do is buy a .20 over piston kit and have the machine shop bore the jugs to the pistons. Quote
sheefreak Posted January 11, 2009 Report Posted January 11, 2009 64.25 is 10 over 64.5 is .020 etc. Yes they bore the hole larger. You may not need to bore on your first set of new pistons as long as cylinder is not gouged or already worn to much to place a 64 mill piston w/correct clearence. The shop should be able to measure them for you and tell you what you need. You may just need a new set of pistons and a hone. Quote
blaster2006 Posted January 11, 2009 Author Report Posted January 11, 2009 64.25 is 10 over 64.5 is .020 etc. Yes they bore the hole larger. You may not need to bore on your first set of new pistons as long as cylinder is not gouged or already worn to much to place a 64 mill piston w/correct clearence. The shop should be able to measure them for you and tell you what you need. You may just need a new set of pistons and a hone. so your saying, the stock bore gets larger from wear etc? never knew that , good to know. and if i get only hone and pistons, meaning its most probably bigger pistons just from that hone, id be getting new pistons ey? if i posted pics of the cylinder, could you guys tell if it needs boring? Quote
boneyardbanshee. Posted January 11, 2009 Report Posted January 11, 2009 I would say if we can tell by looking at a photo over the internet then yes they will need bored. Are they smooth? If there are any scratches they will need bored. Post them up, lets have a look. Quote
sheefreak Posted January 11, 2009 Report Posted January 11, 2009 You don't even necessarily need new pistons. I ran a set of pistons for 3 yrs and just re ringed them every year. Every time you put a new set of rings in a cyl, wether it be on new pistons or old, bore job or not, you need to hone so the rings will seat correctly. Just like anything else, there is a tolerance at which you can run a set of pistons to bore size. You don't want to run them any more then .003 to .004 clearance. DO NOT bore unless you need to. Do you see what I am saying? Wherever you take them to should be able to tell you your best route unless they are just trying to get over on you and want to charge for a bore job and a set of pistons. Quote
kawiking Posted January 11, 2009 Report Posted January 11, 2009 http://www.wiseco.com/PDFs/Catalogs/CB07/YamahaATV.pdf 64.00mm stock 64.25-- 10 over 64.50-- 20 over 64.75-- 30 over 65.00-- 40 over and so on Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.