Kramer3 Posted March 22, 2016 Report Share Posted March 22, 2016 Im about to get my cylinders bored out for the last time at 66.5mm. I am redoing this banshee and tore the top end apart and one of the rings was busted. When you look at the charts for piston to wall clearance for a banshee it says .003 to .0035 clearance, does that mean .003 each side so .006 total or .003 total and .0015 on each side? And does anyone know the size of there cylinders with 66.5mm pistons? Thanks for the help. I appreciate it. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 22, 2016 Report Share Posted March 22, 2016 Those clearances out of an OEM style manual? If so, those clearances will change if forged pistons like Weisco are used. Leave that to the machinist to determine. If he is asking you what clearances should be, find a different machinist with the proper experience. The clearances will be figured by subtracting the piston dimension from the bore dimension. Always check it assembled with feeler gauges. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 22, 2016 Report Share Posted March 22, 2016 Also, make sure the head is able to handle the additional bore size as well. If it were me, it would be time for new cylinders. Quote Link to comment Share on other sites More sharing options...
Kramer3 Posted March 22, 2016 Author Report Share Posted March 22, 2016 I actually bought a WSM race top end rebuild kit off a guy I know that never used it. All brand new in the box. Everything was still wrapped in the original plastic. The guy I got if off of said that if I went to the website that he bought it all from that they had a chart on there. I got that clearance from atvpowerplus.com. I got a deal on the kit so I figured I would do this before I went to sleeves. I have 34mm flat slide mikuni that I'm gonna run on it but haven't figured out what exhaust I'm gonna run yet. I haven't taken my cylinders to a machine shop yet but was just trying to make sure I was straight with it all so when I do take them I can make sure they know what they are doing. Thanks for the help Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted March 22, 2016 Report Share Posted March 22, 2016 Basically a 66.5 bore is just that, piston would be 66.4xxx. Quote Link to comment Share on other sites More sharing options...
registered user Posted March 23, 2016 Report Share Posted March 23, 2016 piston clearance is simply the bore diam minus the piston diam. usually measured at the skirt bottom and 90* to the wristpin. so to answer your question yes the .003 would be .0015 each side. btw the manual says .0024-.0026 for oem piston tricked most any modern forged piston uses nearly the same clearance as a cast piston, within .0005 or so. theres still plenty of urban legend going around that forged needs more clearance but for the most part that really isn't true now days Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 23, 2016 Report Share Posted March 23, 2016 piston clearance is simply the bore diam minus the piston diam. usually measured at the skirt bottom and 90* to the wristpin. so to answer your question yes the .003 would be .0015 each side. btw the manual says .0024-.0026 for oem piston tricked most any modern forged piston uses nearly the same clearance as a cast piston, within .0005 or so. theres still plenty of urban legend going around that forged needs more clearance but for the most part that really isn't true now days On the contrary, I've always had guys setting up motors tighter with forged Pistons. Quote Link to comment Share on other sites More sharing options...
registered user Posted March 23, 2016 Report Share Posted March 23, 2016 the statement about forged being nearly the same as cast is if you compare the recommended specs of wiseco vs oem or most any other cast for that matter. wiseco says .003 on the 513 series box, oem manual says .0024-.0026. if you compare wiseco to oem on other brands such as Honda and ktm you end up with nearly the same clearance of both pistons as well as for which piston can be set with the least amount of clearance and not seize, I don't know that answer. but im quit sure if the machine work is tip top and prep work is good you could probly use less than the manufacturers specified clearance. and if you can consistently keep the engine cooler then you may be able to reduce the clearance even further for this reason also Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 23, 2016 Report Share Posted March 23, 2016 the statement about forged being nearly the same as cast is if you compare the recommended specs of wiseco vs oem or most any other cast for that matter. wiseco says .003 on the 513 series box, oem manual says .0024-.0026. if you compare wiseco to oem on other brands such as Honda and ktm you end up with nearly the same clearance of both pistons as well as for which piston can be set with the least amount of clearance and not seize, I don't know that answer. but im quit sure if the machine work is tip top and prep work is good you could probly use less than the manufacturers specified clearance. and if you can consistently keep the engine cooler then you may be able to reduce the clearance even further for this reason also Any experience with piston coatings? I've done quite a few motors with parts coated from Line 2 Line and after break in, I'm seeing just over .0020. I've gone one like that with almost 5 years on it. I'll find a link on it. Pretty cool stuff. It's anti friction, and is meant to wear in so the piston takes a perfect shape to the bore. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted March 23, 2016 Report Share Posted March 23, 2016 http://www.line2linecoatings.com/ Quote Link to comment Share on other sites More sharing options...
registered user Posted March 24, 2016 Report Share Posted March 24, 2016 some wisecos have some sort of coating. some of their stuff doesn't. not sure what the deal is. but ive used a couple of the wiseco Hondas with the coating. really couldn't say if there was a benefit or not. seems like the oem vertex I took out of my new ktm had a coating but it was cheesy and mostly worn off in 5hrs. tried the thick swain tech stuff to tighten up the clearance on a old ktm engine because pistons were no longer available at the time. found a hairline crack on the edge of the window so I never ended up using it from what I remember. probly still have it buried in the garage somewhere never tried the stuff you speak of Quote Link to comment Share on other sites More sharing options...
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