racer Posted May 18, 2004 Report Share Posted May 18, 2004 is it possible to have piston slap only when the cylinders/pistons are cold? occasionaly when i start my banshee it makes a slapping type sound from the left jug, and i havent been able to figure it out. so, after reading some on what it is and what it can do to your pistons and jugs, i have decided to ask about it before i destroy my motor . motor is all stock except air filter and jetting, i just bought it in oct. so i dont know the last time it was rebuilt, but i do know that it was done with vitos's pistons (unsure of what model), compression is 90/85, any help will be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
pimp559 Posted May 18, 2004 Report Share Posted May 18, 2004 The compression sounds pretty low especially the 85 which is almost 10% off of the 90. Sounds like its time for a new set of rings at least. I would take the head off and take a look first. It may be to late to just re-ring. Quote Link to comment Share on other sites More sharing options...
MotulMonsta Posted May 19, 2004 Report Share Posted May 19, 2004 yeah, it's possible..as the engine warms all the parts expand. Quote Link to comment Share on other sites More sharing options...
U8RSAND-Az Posted May 19, 2004 Report Share Posted May 19, 2004 Does it do it when after it warms up? What type of pistons are they? Cast or forged? Cast pistons are less dense than forged and thus expand less when heated so you can run tighter piston to wall clearence and will last longer between bores. However forged pistons are far stronger because they are denser but expand more when heated and need more piston to wall clearence. Your best bet is to just bite the bullet and bore the cylinders and put in a good set of forged pistons. When you go riding start the bike let it idle for a few minutes before riding, I like to touch the sides of the cylinders to see how warm they are. One more thing don't start it and then rev it up constantly like a lot of people do thats not good on a cold engine!!! Fools Quote Link to comment Share on other sites More sharing options...
racer Posted May 19, 2004 Author Report Share Posted May 19, 2004 yes, it does it after it warms up, but not as often. no, i have no idea what type of pistons they are, is there any way to tell? I alwaya warm it up properly, however i cant say for the guy who owned it before me. when i do ride it i always let it idle until it is too hot to put my hand directly on the head. can i pull the head and jugs and have them mic'd to see what the clearances are, or do i just need to say, f$$k it and have it redone. I'd rather just drop 250 on a bore job than break a shirt and end up buying a top and bottom end. Quote Link to comment Share on other sites More sharing options...
U8RSAND-Az Posted May 19, 2004 Report Share Posted May 19, 2004 Well you could pull it apart and see what you have. Any good shop can mike the pistons and put a dial bore gauge in the cylinders and tell you what you have in just a couple minutes. If you're really worried about it thats what I would do or at the very least take it to a good shop and let them listen to it. Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted May 19, 2004 Report Share Posted May 19, 2004 is it hard starting? with that low of compression i would think it would be hard to get it going. i would just do a total topend rebuild. have it bored and go with wiseco pistons, rings, etc..might as well go ahead and have it done because its more than likely not running to its potential. if you have a local shop just have them bore it for you, then you can put it all back together. if you have some money you may wanna go ahead and get a noss head with some smaller domes to raise compression a little more. it would be nice to do it now as youll have the head off. but whatever you do id have it rebuilt. Quote Link to comment Share on other sites More sharing options...
racer Posted May 19, 2004 Author Report Share Posted May 19, 2004 im thinking the reed may be getting just a bad seal because it always starts first kick, may not idle first try but always spits and sputters. ok ill tear the topend off, always wanted a reason to do it anywas, and have it dialed a good friend of mine is working at the local stealership, ill have him take it to his machinist. i once heard a rumor that you will never get a truly accurate reading on a two stroke because the reeds will never get a perfect seal like valves will, is that true? yeah i decided on wiseco's a while back when i first thought it needed to be done but that turned out to be the stator. as for the head im gonna have it shaved this summer when im working more cause school will be out. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
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