Kev55 Posted July 22, 2010 Report Share Posted July 22, 2010 I'm new to banshee's and I'm looking for some advice about picking a piston kit. Like alot of people I'm on a budget and I'm looking to find parts cheap so i went to ebay for some kits. there are 2 different kits listed for my size bore. Wiseco Piston Top end kit $195.00 http://cgi.ebay.com/ebaymotors/Wiseco-Piston-Top-End-Kit-Yamaha-Banshee-350-080-_W0QQcmdZViewItemQQhashZitem359f240c0eQQitemZ230303206414QQptZMotorsQ5fATVQ5fPartsQ5fAccessories#ht_1081wt_1165 Namura Piston Top end kit $152.00 http://cgi.ebay.com/ebaymotors/Yamaha-Banshee-Namura-080-Pistons-Gaskets-Bearings-Kit-_W0QQcmdZViewItemQQhashZitem2eae545474QQitemZ200493257844QQptZMotorsQ5fATVQ5fPartsQ5fAccessories#ht_1387wt_877 Both come w/ pistons, bearings, and gaskets just different brands. is Wiseco worth the extra 40? Quote Link to comment Share on other sites More sharing options...
alf44 Posted July 22, 2010 Report Share Posted July 22, 2010 PM sent. Buy from a sponsor. Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted July 22, 2010 Report Share Posted July 22, 2010 First , welcome to BHQ !! You get EXACTLY what you pay for . Namuras are cast (same as stock ) , Wiseco are forged therefore stronger . It will depend on your use . Next, are you sure about the piston size you have chosen ? .080 over ? You have measured your bore and it is .060 over now? Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted July 22, 2010 Report Share Posted July 22, 2010 Also try to deal with site sponsers. First off they help keep this site up and running. Next is customer service , some E-gay site either might not care about feedback or just change site name and still sell crappy costomer service . JMO , your results may vary. Quote Link to comment Share on other sites More sharing options...
Kev55 Posted July 22, 2010 Author Report Share Posted July 22, 2010 First , welcome to BHQ !! You get EXACTLY what you pay for . Namuras are cast (same as stock ) , Wiseco are forged therefore stronger . It will depend on your use . Next, are you sure about the piston size you have chosen ? .080 over ? You have measured your bore and it is .060 over now? yeah it's .080 i bought a caliper and measured the pistons at 66mm and the cylinder at 66.4mm man everyone he is so helpful and welcoming + you get awesome sponsor deals BHQ is AWESOME! Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 22, 2010 Report Share Posted July 22, 2010 You shouldn't buy pistons until you have had your cylinders measured to see what size you need. Quote Link to comment Share on other sites More sharing options...
Kev55 Posted July 23, 2010 Author Report Share Posted July 23, 2010 You shouldn't buy pistons until you have had your cylinders measured to see what size you need. I measured the cylinders at 66.4 and pistons at 66. I still have to hone the cylinders out though. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 23, 2010 Report Share Posted July 23, 2010 I measured the cylinders at 66.4 and pistons at 66. I still have to hone the cylinders out though. All a calipar is good for is to tell you what size your pistons are. It cannont accuratly measure piston to cylinder clearances. Your dealing with to small of numbers. Forged pistons generally require 0.003 in or 0.0762mm. A calipar can only measure in bore at the top. It cannont meausre half way down in to the cylinder. That is where the most wear occurs and the clearance will be larger than at the top of the bore. The top of the bore can also be the same as the day it was bored because the piston rings do not go up that far. So if your pistons are 66.00mm you need your bore to be 66.0762mm, 66.400mm bore is to large by 0.3238mm. You need a bore (inside) micrometer, and a regular micrometer to properly measure pistons and bores to determine the correct size. That is why you should wait to get your pistons after you have the cylinders measured. Yea you can hone the cylinder throw the same size piston back in and it will run. But if the clearances are to large then your pistons wont last long. They can rock back and fourth in the bore, breaking the skirts off and causing all kinds of damage. When you should have went up to the next size and had the cylinders bored. Quote Link to comment Share on other sites More sharing options...
Kev55 Posted July 23, 2010 Author Report Share Posted July 23, 2010 (edited) All a calipar is good for is to tell you what size your pistons are. It cannont accuratly measure piston to cylinder clearances. Your dealing with to small of numbers. Forged pistons generally require 0.003 in or 0.0762mm. A calipar can only measure in bore at the top. It cannont meausre half way down in to the cylinder. That is where the most wear occurs and the clearance will be larger than at the top of the bore. The top of the bore can also be the same as the day it was bored because the piston rings do not go up that far. So if your pistons are 66.00mm you need your bore to be 66.0762mm, 66.400mm bore is to large by 0.3238mm. You need a bore (inside) micrometer, and a regular micrometer to properly measure pistons and bores to determine the correct size. That is why you should wait to get your pistons after you have the cylinders measured. Yea you can hone the cylinder throw the same size piston back in and it will run. But if the clearances are to large then your pistons wont last long. They can rock back and fourth in the bore, breaking the skirts off and causing all kinds of damage. When you should have went up to the next size and had the cylinders bored. well i have the heads off right now so would it be more accurate if i just turn it upside down and stick the caliper in from the other end and measure? I'm trying to avoid boring it out just cuz i dont wanna then start having over heating problems w/ even thinner walls. Edited July 23, 2010 by Kev55 Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 24, 2010 Report Share Posted July 24, 2010 well i have the heads off right now so would it be more accurate if i just turn it upside down and stick the caliper in from the other end and measure? I'm trying to avoid boring it out just cuz i dont wanna then start having over heating problems w/ even thinner walls. You wont have overheating problems. There have been plenty of people running 66.5mm (.100 in) over with no problems. You just cant accuratley meauser the bore. It would be like trying to use a ruler. The measurements needed are to small. You need to take them off and have them measured by a machine shop or motorcycle shop. If you just take them to a motorcycle repair shop and have them meausure them they will be able to tell if you can just hone the cylinder and put 66mm pistons in or if you need to go up a size. Your cylinders are at the end of there life ethrire way. Just as well start looking for a good pair of replacemts. Find some that are already ported if you want to save some cash. You can do what you want, throw another set of 66mm pistons in and cross your fingers or you can atleast have the cylinders measured. Quote Link to comment Share on other sites More sharing options...
Kev55 Posted July 24, 2010 Author Report Share Posted July 24, 2010 You wont have overheating problems. There have been plenty of people running 66.5mm (.100 in) over with no problems. You just cant accuratley meauser the bore. It would be like trying to use a ruler. The measurements needed are to small. You need to take them off and have them measured by a machine shop or motorcycle shop. If you just take them to a motorcycle repair shop and have them meausure them they will be able to tell if you can just hone the cylinder and put 66mm pistons in or if you need to go up a size. Your cylinders are at the end of there life ethrire way. Just as well start looking for a good pair of replacemts. Find some that are already ported if you want to save some cash. You can do what you want, throw another set of 66mm pistons in and cross your fingers or you can atleast have the cylinders measured. na if I'm gonna do it i want it done right so i dont have to worry about it all. I'll just take them to get measured and see what they tell me. thanks for your help! Quote Link to comment Share on other sites More sharing options...
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