wedge Posted April 8, 2007 Report Posted April 8, 2007 OK, so i have had my banshee for about 8 months now and i keep breaking pistons skirts, for about the first 2 1/2 months it was fine, and then my top end went on the left cylinder but it didn't break the skirt and it was just one cylinder so i still had one fine piston. I then got a set of pistons off a buddy that were in perfect condition, and then my bottom end went one the left side. so then i bought a motor off ebay, it was almost complete but it was missing the trans gears and some bolts and shit but i had all that from my old motor, so i put the new cylinders, crank and pistons that were bored .040 in and it broke the skirt on the left cylinder, so i put my old cylinders on with the old pistons and it broke one skirt in the right cylinder, then it broke the skirt on the left cylinder. for the winter i decided to take it apart and paint some stuff so i did and then bought some pistons for the bored cylinders, and i also bought a 2 into 1 intake trying to elaminate leaning of one cylinder, so everything was fine for about a month and then the left skirt broke agin, over all i have 5 or 6 broken pistons so i am fed up with it and i am not going to try fixing it untill i find out the problem, sorry for the long post and thank you for your help Quote
scooter Posted April 8, 2007 Report Posted April 8, 2007 are you boring the cylinders before installaing theses pistons? are you checking the pistons before installing them? sounds like the pistons are rocking back and forth in the cylinders and breaking the skirts. just a thought Quote
Shee-Male Posted April 8, 2007 Report Posted April 8, 2007 Take the cylinders to a local machine shop, have them honed to the next size to make them straight with proper clearance, and put in a fresh set of Wiseco forged pistons & rings...problem solved and cheaper then buying used pistons here, used topends there and not knowing what condition they are really in. Do it once & do it right and problems will be gratly minimized! Quote
wedge Posted April 8, 2007 Author Report Posted April 8, 2007 Take the cylinders to a local machine shop, have them honed to the next size to make them straight with proper clearance, and put in a fresh set of Wiseco forged pistons & rings...problem solved and cheaper then buying used pistons here, used topends there and not knowing what condition they are really in. Do it once & do it right and problems will be gratly minimized! i can try that but i am on a realy tight budget, so i might have to wait a wile, but they were also breaking in stock bore cylinders with pistons that came in it from the factory? Quote
bansheefourseven Posted April 8, 2007 Report Posted April 8, 2007 Theres a thing called piston slap which means either your bore job isnt done to match the pistons your using making piston clearance way too much. I like to buy the pistons and take them to the shop when you get the bore done that way they can make damn sure both match up correctly . Quote
KHall Posted April 8, 2007 Report Posted April 8, 2007 Just a thought r u replacing the wrist pin bearings if they go out that will cause piston to rock side ways in cylnder 2 Quote
decibles Posted April 8, 2007 Report Posted April 8, 2007 Another thing that may be causing your problem if the ports in the cylinders aren't chamfered the rings can slightly hang up on them which forces the piston to rock against the skirt I have seen this happen on perfectly bored cylinders that the machine shop failed to chamfer. I have also seen a set of wiseco pistons put in cylinders that were worn beyond specs (we were at the glamis dunes and wanted to run one more day) run for 6 months of hard riding all I did was use a stone hone to break the glaze and then chamfered the ports a little more and away we went. I pulled the motor apart after 6 months since it was to hot to ride anyway. I myself was shocked to find perfect pistons. I actually wished I hadn't torn it down I just figured it was beyond the limits. I may be the only person that thinks not chamfering could be the cause but it's worth taking a look at. Quote
letsgetthisdone Posted April 8, 2007 Report Posted April 8, 2007 (edited) You're on a tight budget, but how much money have you spent on used stuff that lasted 2 months. Buy a new wiseco piston kit, have the cylinders bored to match (and make sure the ports get chamfered), and if the crank is bad, buy a new one. A new crank will last at least 5-6 top-ends (prolly more) and a fresh (brand new) top end should last at least a year of consistent riding (2-3 times a month). EDIT: A wise man once said, "you can go broke saving money." :thumbsup: Edited April 8, 2007 by letsgetthisdone Quote
dajogejr Posted April 8, 2007 Report Posted April 8, 2007 You're on a tight budget, but how much money have you spent on used stuff that lasted 2 months. Buy a new wiseco piston kit, have the cylinders bored to match (and make sure the ports get chamfered), and if the crank is bad, buy a new one. A new crank will last at least 5-6 top-ends (prolly more) and a fresh (brand new) top end should last at least a year of consistent riding (2-3 times a month).EDIT: A wise man once said, "you can go broke saving money." :thumbsup: Yep...beat me to it. Quote
David Keith Posted April 10, 2007 Report Posted April 10, 2007 Yep...beat me to it. You guys are right. I had a set of cylinders bored out last year & the machinist assured me that the cylinders did not need to be chamfered... I argued with him & he said to try running it with the fresh bore job/ not chamfer. It locked up in less than five minutes. Quote
yamaha04 Posted April 10, 2007 Report Posted April 10, 2007 You guys are right. I had a set of cylinders bored out last year & the machinist assured me that the cylinders did not need to be chamfered... I argued with him & he said to try running it with the fresh bore job/ not chamfer.It locked up in less than five minutes. hope you sent that bitch back yellin Quote
dynodon Posted April 10, 2007 Report Posted April 10, 2007 I am sorry for being off the topic here, BUT David K. what state do you live in to have found a moral like that ???? That is HUGE !!!!!!! Back to the topic, what pistons were you using ??? It does sound like a chamfer problem like the others have said Quote
David Keith Posted April 10, 2007 Report Posted April 10, 2007 I am sorry for being off the topic here, BUT David K. what state do you live in to have found a moral like that ???? That is HUGE !!!!!!!Back to the topic, what pistons were you using ??? It does sound like a chamfer problem like the others have said Yes, it's the largest one I've ever found. Right here in Ohio, just above Dayton. It was an eleven incher! Quote
dynodon Posted April 11, 2007 Report Posted April 11, 2007 Yes, it's the largest one I've ever found. Right here in Ohio, just above Dayton. It was an eleven incher! WOW !!!! I am from Northern Michigan, we always hunted traverse area and NEVER found any like that!!!, Thats awsome, Great find !!!!! Quote
375hp banshees Posted April 11, 2007 Report Posted April 11, 2007 WOW !!!! I am from Northern Michigan, we always hunted traverse area and NEVER found any like that!!!, Thats awsome, Great find !!!!! I've been wondering what that was whats A moral? Quote
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