pcplatinum21 Posted September 4, 2012 Report Posted September 4, 2012 i have banshee cylinders that are .50 over and i measured the cylinders and there 64.7 , is that to far to get new pistons or do i need to get them bored, my compression was still 110 in each cylinder.. just wanting to know if its ok for new pistons or needing bored! Quote
gotta_goatsfast Posted September 4, 2012 Report Posted September 4, 2012 What does this have to do with jetting and exhaust? I think what you are asking is... "I measured my cylinder and read 64.7mm on a 0.050" overbore. Do I need to bore to the next size?" If so, then first off you cannot measure a cylinder bore to the tenth of an inch.... you need to be much more exact (think hundreth of an inch in several spots including perpendicular and top/mid/bottom bore). Secondly, a 0.050" overbore would result in a total diameter of 65.27mm (in perfect math) so if you're seeing 64.7mm these cylinders were not bored 0.050". Maybe .50mm??? This would result in a bore of 64.5mm and since your measuring tool only goes to the tenth of a millimeter, I would venture to guess its not very accurate. My advice is to send it to a sponsor here. Let them check out what you have. They have the experience to recommend you a hone/ring if your cylinders check out or a rebore and piston kit if needed. They'll have the tools and experience to do this right. Quote
pcplatinum21 Posted September 4, 2012 Author Report Posted September 4, 2012 i didnt say it was .050 over,its .50mm over its a 64.50mm piston and the bore reads 64.7 on a caliper on top and bottom, i know i need a dial bore gauge to accuratly measure i was just wondering if it would need bored reading 64.7, i know the wear limit is usually 12 thousands of an inch but im not sure how to convert that to mm!! i think im going to take the cylinders somewhere to get them checked!! it ran when i pulled it apart just was hard to start! Quote
gotta_goatsfast Posted September 4, 2012 Report Posted September 4, 2012 0.012" x 25.4 (conversion to mm)= 0.3048mm Sorry, I read through it fast and didn't see the decimal, thought it was just "50 over". Anyway, I like to be fairly precice on PTW clearance... which means using a caliper that reads to one decimal place won't cut it. I would for sure send them out for a professional analysis. The more "love" you put into your banshee, the more love your banshee will give back to you! Quote
pcplatinum21 Posted September 5, 2012 Author Report Posted September 5, 2012 alright, thats what ill do, im going to take them to a service shop asap, thanks for the advice, thats a good analogy "The more "love" you put into your banshee, the more love your banshee will give back to you!", i am hoping that because the piston is 64.50mm that the bore is bigger so the piston has clearance to swell up when engine is warmed up!! i dont know how much tho thats why i need pro help lol, thanks again!! Quote
gotta_goatsfast Posted September 5, 2012 Report Posted September 5, 2012 Have you ever worked with any of our site sponsors? They offer fair prices and all they do is banshees. Not saying local shops will screw up, just remember that some shops don't re-chamfer the ports and don't know the PTW clearances for various cylinder/piston combos and will use a general size. Quote
pcplatinum21 Posted September 5, 2012 Author Report Posted September 5, 2012 no, im new to this site, i have a local machinist who has been boring, milling, sleeving, and pressing for over 75 years, hes always done a great job on past projects of mine!! Quote
lms1977 Posted September 5, 2012 Report Posted September 5, 2012 most people dont have bore guages, the closest thing you could do is clean everything as clean as you can and put a feeler guage in the bore and try to see what size you can go up to untill the piston wont fit. but .012 sounds like waaaaay to much to me Quote
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