90Bansheedude Posted June 6, 2009 Report Share Posted June 6, 2009 Ive measured several times, and I keep getting 64.80mm. Is this acceptable with a light hone (no deep scratches) to drop in a set of wiseco or other (recommend brand) pistons that are for a 64.75 bore. Current pistons are toast. Maybe im being over careful, but I dont want to bore if i dont have to, but I dont want it to blow up or run like $hit either! Simple question for an experienced builder. Thanks Brian Quote Link to comment Share on other sites More sharing options...
Burt Reynolds Posted June 6, 2009 Report Share Posted June 6, 2009 The only way to be sure its right is to take them to a good machinist or someone that bores cylinders,and have them check it out. Unless your really sure on how to measure them i would not chance it. Quote Link to comment Share on other sites More sharing options...
swrbansheeboy Posted June 6, 2009 Report Share Posted June 6, 2009 i agree, take it to a builder to get checked out. i have no doubt that it will run with 5mm clearance but for a fresh bore and hone your supposed to have around 2mm... Quote Link to comment Share on other sites More sharing options...
FireHead Posted June 6, 2009 Report Share Posted June 6, 2009 The only way to be sure its right is to take them to a good machinist or someone that bores cylinders,and have them check it out. Unless your really sure on how to measure them i would not chance it. Word. You need to have a bore gauge or a proper ID micrometer. Quote Link to comment Share on other sites More sharing options...
90Bansheedude Posted June 6, 2009 Author Report Share Posted June 6, 2009 Word. You need to have a bore gauge or a proper ID micrometer. all i have is a regular old digital set of calipers Ill see if the machinist is open tomorrow. Quote Link to comment Share on other sites More sharing options...
toolman Posted June 6, 2009 Report Share Posted June 6, 2009 You need to check for out of round and taper also not just overall size. Time and money spent now will save you later. Quote Link to comment Share on other sites More sharing options...
Building my First Posted June 6, 2009 Report Share Posted June 6, 2009 Even if the bore is true, at .05 mm of wear you are going to get some blow by and probably loss in compression not to mention those new pistons will get slapped up faster. .03 is the max I would let it go. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted June 6, 2009 Report Share Posted June 6, 2009 (edited) you will need to get the cylinders mic'ed up for taper and out-of-round. also, if your cylinders measure up to be 64.8mm and the pistons measure up to be 64.75mm, then you are getting a piston to cylinder clearance of .05mm, which is .002". maybe a little tight, if running wiseco pistons?? and the rings do the sealing, not the pistons, so don't think that the pistons are what causes the blow by. Edited June 6, 2009 by mopar1rules Quote Link to comment Share on other sites More sharing options...
RagunCajun Posted June 6, 2009 Report Share Posted June 6, 2009 Anybody have a link on how you check taper and for out of round? I have a 2"-12" Starrett ID mic set. And ima machinist so i can possible get gauges from work. Quote Link to comment Share on other sites More sharing options...
90Bansheedude Posted June 6, 2009 Author Report Share Posted June 6, 2009 Anybody have a link on how you check taper and for out of round? I have a 2"-12" Starrett ID mic set. And ima machinist so i can possible get gauges from work. I took them to the machinist, he checked them, and said they looked good and consistent. So, im going to order some pistons, probably the ones in the link below. Ive got my current problem taken care of, but for future reference, when I order a set of pistons... say for example RJATV Ebay Wiseco 64.75 piston set Are the pistons going to be 64.75, or should the bore be 64.75, or what, im kinda confused!? If the bore is supposed to be 64.75, then anything over that is wear, or is it a common practice to give them a little more space for clearance? Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted June 7, 2009 Report Share Posted June 7, 2009 (edited) you need to have the bores matched to the pistons, to have the correct piston/cylinder clearance. you have to have some clearance in there. you can't have a piston that measures 64.75mm for example and a bore that measures 64.75mm. you will have seizure within minutes of running, if you get the piston to fit inside the bore ok, seeing as that would be a "size-on-size" fit. you need to have like .003" clearance, for stock bore and stock cast pistons. larger pistons and forged pistons, require more clearance. the bore will always be a few thousandths larger in diameter, than the piston, to allow room for the piston to "grow/expand", when it gets warm while running. understand? if i'm not mistaken, the pistons should measure the 64.75mm or whatever is stamped on the domes, and the bore is going to be a few thousandths over that. for measuring bore diameters and taper, you take measurements at 3 points thru the bore. you measure at approx 1/2" down from the cylinder deck, straight across where like the wristpin would be and then 90* from that measurement. then do the same in the middle of the cylinder bore and then again at like 1/2" up from the cylinder bottom. compare the measurements throughout to compare and find out the taper and out-of-round. out of round should be no more than .0005" and the taper like no more than .002". hope this helps. maybe someone else can explain it better than me. Edited June 7, 2009 by mopar1rules Quote Link to comment Share on other sites More sharing options...
FireHead Posted June 7, 2009 Report Share Posted June 7, 2009 I took them to the machinist, he checked them, and said they looked good and consistent. So, im going to order some pistons, probably the ones in the link below. Ive got my current problem taken care of, but for future reference, when I order a set of pistons... say for example RJATV Ebay Wiseco 64.75 piston set Are the pistons going to be 64.75, or should the bore be 64.75, or what, im kinda confused!? If the bore is supposed to be 64.75, then anything over that is wear, or is it a common practice to give them a little more space for clearance? Go to Wiseco's website and pu;l up the bore and piston spec.'s out of their catalog. :cool: Quote Link to comment Share on other sites More sharing options...
90Bansheedude Posted June 7, 2009 Author Report Share Posted June 7, 2009 Go to Wiseco's website and pu;l up the bore and piston spec.'s out of their catalog. :cool: Wiseco Part#: 513M06475 Product Type: Single Pistons Description: YAM RZ350/BANSHEE PRO-LITE 2549CD Displacement: 355cc Bore - Standard: 64.00mm Bore - Actual: 64.75mm Bore - Oversize: 0.75mm Stroke: 54.00mm Cylinders: 2 Note: Pro-Lite Note: Liquid cooled Installation notes...It doesn't seem to tell me what Im looking for, but it is interesting! Drill 2 holes in my new pistons! Is this true!? Wiseco M series Piston Install Inst. Quote Link to comment Share on other sites More sharing options...
RagunCajun Posted June 7, 2009 Report Share Posted June 7, 2009 90Bansheedude, you quoted me and didnt answer my question. If you scroll down you can click add replay if you dont need to quote something. Thanks mopar1rules. That does make sense. I should of know that's how you measure the taper. It's common sense, heh. Just needed to know the tolerances of course. I dont and my shop doesnt have anything that measure Quote Link to comment Share on other sites More sharing options...
Meat Posted June 7, 2009 Report Share Posted June 7, 2009 Drill 2 holes in my new pistons! Is this true!? Wiseco M series Piston Install Inst. I just put a new set of Wisecos in my bike and was looking at the instruction sheet thats included with the piston kit and I read the same damn "drill two holes" line. I was like... "fuck that shit, I ain't drillin my shiny new pistons". Quote Link to comment Share on other sites More sharing options...
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