HARRY64CHEVY Posted March 4, 2007 Report Share Posted March 4, 2007 I just bought a 99 banshee for $1500. alls It needed was a throttle cable. (or so i thought) I replaced cable rode it for approx 10 mins. and it died. So i tore it down and somebody said to find what it was bored out to you have to read the pistons. So i cleaned them off and noticed that they were different. The left piston had 1.00 mm and the rh side had 0.50 mm. anyone ever here of this? the part numers on each pistons are LH - A78F2 1.00 MM 513 P4 RH - F72LO 0.50 MM 513 P2 CAN ANYONE EXPLAIN THIS??? i guess i have to redo the top end what are the steps i should take? Quote Link to comment Share on other sites More sharing options...
csrmel Posted March 4, 2007 Report Share Posted March 4, 2007 normally the cylinders wear at relatively similar rates. somtimes 1 cylinder will wear out quicker than the other (if it ingest dirt, airleak, run lean etc). sounds like the previous owner was a cheap ass and had each cylinder rebuilt only when that individual cylinder needed it. i bet that 1.00mm cylinder wore out quicker than the other for a certain reason, so it was rebuilt twice as often. you must find out why this cylinder was bored bigger. what you might consider is pulling the cylinders, having them borh bored out to be equal and grab some new pistons. check the crank while you are in there for excessive play. when you have the engine back together make sure there are no air leaks, and the jetting is good (even a little rich is ok for testing purposes). once you get the engine back together and have the banshee running good, then it is time to go over the rest of the bike for problems. if the previous owner was cheap enough to get the cylinders bored at different times, chances are good he did some other cheap ass things to the rest of the quad. dont feel like you got a bad deal though. $1500 is a good price for a banshee, even if its not running. so you still got a good deal, just not as good as you originally though. Quote Link to comment Share on other sites More sharing options...
FASTOYS Posted March 4, 2007 Report Share Posted March 4, 2007 I would definetly tear it down and make sure they are bored correctly to the SAME size. Its not good to run a twin cyl with different size pistons!! Quote Link to comment Share on other sites More sharing options...
IROOST1 Posted March 4, 2007 Report Share Posted March 4, 2007 I know its normal for snowmobiles to have different size bores. I thought that was odd but thats what the manufactures say is ok to do. But that much of a difference, i would get a new top end. Quote Link to comment Share on other sites More sharing options...
HARRY64CHEVY Posted March 4, 2007 Author Report Share Posted March 4, 2007 normally the cylinders wear at relatively similar rates. somtimes 1 cylinder will wear out quicker than the other (if it ingest dirt, airleak, run lean etc). sounds like the previous owner was a cheap ass and had each cylinder rebuilt only when that individual cylinder needed it. i bet that 1.00mm cylinder wore out quicker than the other for a certain reason, so it was rebuilt twice as often. you must find out why this cylinder was bored bigger. what you might consider is pulling the cylinders, having them borh bored out to be equal and grab some new pistons. check the crank while you are in there for excessive play. when you have the engine back together make sure there are no air leaks, and the jetting is good (even a little rich is ok for testing purposes). once you get the engine back together and have the banshee running good, then it is time to go over the rest of the bike for problems. if the previous owner was cheap enough to get the cylinders bored at different times, chances are good he did some other cheap ass things to the rest of the quad. dont feel like you got a bad deal though. $1500 is a good price for a banshee, even if its not running. so you still got a good deal, just not as good as you originally though. thanx alot for the info...that is what i plan on doing, tearing the cylinders off the bike this week does anyone live in the PA area that knows where i can send the cylinder to get bored and a good place to get new pistons? Quote Link to comment Share on other sites More sharing options...
JET 99 Posted March 4, 2007 Report Share Posted March 4, 2007 I would definetly tear it down and make sure they are bored correctly to the SAME size. Its not good to run a twin cyl with different size pistons!! thanx alot for the info...that is what i plan on doing, tearing the cylinders off the bike this week does anyone live in the PA area that knows where i can send the cylinder to get bored and a good place to get new pistons? the man that replied to your question above is quite capable of doing both!!!!! :thumbsup: his name is jeff. he is the man behind fastoys...... Quote Link to comment Share on other sites More sharing options...
HARRY64CHEVY Posted March 4, 2007 Author Report Share Posted March 4, 2007 the man that replied to your question above is quite capable of doing both!!!!! :thumbsup: his name is jeff. he is the man behind fastoys...... thanx i will check them out anyone know of any shops in PA philly area that does bore jobs? Quote Link to comment Share on other sites More sharing options...
. Posted March 5, 2007 Report Share Posted March 5, 2007 look in dirtwheels or talk to guys on here, you should be able to get a rebuild kit shipped to your door around 150 dollars including bearings and top end gasket kit. pull the cylinders, take them to a local machine shop (if your in the lansdale, souderton, montgomeryville area I can recommend some places) and get them mic'd and see what you can get away with for bore size. Order the pistons and when you get them, take them back to the machinist and make sure he bores the cylinders to his mic'd specs of the pistons. pistons read to the hundredths, but you can bore to the thousandths.....thats why you have to mic each individual piston. Quote Link to comment Share on other sites More sharing options...
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