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so would it be safest to take it into a machine shop and have it checked? they were the pistons sent with the kit and just assumed they would be correct

Hey guys, just after some advice. I need some replacement pistons for my 392 banshee, old pistons are 67.95mm and i am under the impression the bore size is 68mm as it is a 392cc kit from athena. I would like to get some quality pistons as it seems running a little rich has caused the standard athena pistons to break off the intake ports. The bike will be going in for a tune with a guy who knows banshees so it should get dialled on properly, fingers crossed no more broken skirts! I have come across vitos 68mm pistons and wsm forged 68mm pistons, now they would be to big for my bore correct? Would wiseco do a forged piston of 67.95? Any ideas where else to look? Cheers for the help

this computer wont let me upload pics... not sure why. what brand piston would be good for this rebuild? 67.95mm??

nah didnt check piston to bore clearance, it all came from athena as a bolt on kit. Water pump and radiator are brand new with the rebuild, i just put a standard water pump in with an oversize radiator. Side by side comparison of my old barrels with the athena ones shows the intake ports are noticeably bigger, but i havnt measured anything as of yet. I would say by the looks of the dome and the slight pitting in the head that maybe the skirt has ended up on top of the piston somehow?? if thats possible... may explain the crown damage. Would it be a heat issue to break both skirts or a detonation issue? my pick up gap was way out and it was carrying on like a pig down low once it was hot. Where would be a good place to pick up a set of 67.95mm pistons to throw it back together? As you can probably tell im pretty new to the whole banshee bug. I have had a few 2 wheel 2 strokes and never had a drama with jetting or rebuilds... had some drama with my ktm 525 4 stroke which was a never ending story but never had drama with 2 strokes, its doing my head in!

both pistons are cracked through the skirts. left one is missing the whole bottom of one window, the left is just missing a small piece of the centre, but some cracks through from the centre of the piston. both bores are ok, no marks, nothing to indicate a snag. but the left is missing the intake side of the crown, down to the second ring. I will post some pics tonight, what am i missing with this?

both plugs are quite black,yeh it is stock ignition and no marks in the bore. all the hone marks are still visible. Dirtydownunder, you might know him, Grummer from Grummer racing did my mates 04 with the 330's and the t5's.i spoke to him before going up to the 340's, and i also spoke to perth quad parts who suggested the same thing. My mates 07 running the same pipes only has vents added into his airbox and it was tuned by south coast motorcycles in esperance when he first got it, its running 320's and 25 pilots, his bike is by far the best running stocker i have been around, not sluggish on the bottom at all and is nearly as quick as mine was up top, 280's in mine were to lean, even before this topend went on. bike was overheating in no time and boiling its coolant out. Am i missing something really basic? I have had my carbys off heaps before this happend, could i have got an airleak or something? It has a k&n with outer sock and no lid on the box. Bike has been really shit off the bottom since iv had it, probly worse with the athena top end, but always had a good top end

it was running a little on the hot side, but nothing like when it melted down. it was running 280s with 25 pilots before the athena top end went on, it always ran hot then and after really getting into it, it melted down in a big way after maybe half an hour. that took a similar size chunk out of the piston but was the exhaust side, not the intake side. plus there was a 5mm hole in it, where is now its just a broken crown. the right piston look ok, same colouring, no damage. the bike was good to start, wasnt smoky, just was sluggish on the bottom with a reasonably strong top end. what kind of signs would i be looking for if it was being too rich that caused this?

2 of my mates who are both on stock un-opened engines are running 320/330 mains, both have standard air boxes, one is running same pipes as me the other t6's, with my airbox having no lid shouldnt this be ok? i am at sea level in perth australia... even if it is a lil rich would that cause the crown to break? i will try to get some pics up over the weekend

if a ring got caught there would be a tell tale sign correct? this thing doesnt have a mark anywhere, bike still ran but only on full throttle. I ran an athena piston in my Ktm 525 sx and didnt seem to have a problem though i only put maybe 2 hours on it before i sold it. could a bit of sand past the air filter cause anthing like this? i dont really trust the k&n in the sand, and have a proflow setup to change to once it is running again. Im thinking sand past the airfilter would more likely mark the bore though

After all my stuffing around with jets and electrical problems, turns out my 3 hour old top end has let go. It is an athena 392cc kit, so 67.95 athena pistons. the left one has broken the crown on the intake side, down to the top ring. there is no marks anywhere to indicate a snagged ring. Bike has 27.5 pilots, 340 mains, k&n airfilter with no lid, fmf sst's with powercore 2 silencers, needles are on the middle clip position. Bike seemed to be running slightly rich if anything, what could cause this to happen? Would it be possible that it was just a shit piston? It was only the second ride since the rebuild, any ideas at what might cause this?

hey guys, cheers for the help. Pick up coil was a long way out, reset that and the spark is excellent now... tried to fire it up and still a no go... did a comp test and had about 5 psi in the left, i am having the best luck with this bike! pulled the head and the left piston has broken the crown down to just below the top ring, about 5mm deep, intake side. there is no marks in the bore, nothing to indicate a snagged ring, what else would cause this? Im slightly pissed off with it as its barely run in, could it just be a shit piston? the top end was a complete 392cc athena kit

thanks again fellas, i have a week off as of tuesday so will get stuck into it. would it be ok just to get the stator rewound or better to just get a new one if it is shot?

I havnt even considered checking the pick up gap until now, to be completely honest I didnt even know what it was until now... I will check it out, how do I adjust it properly? And cheers for your 2 cents, the more I learn about this thing the better as I cant stand anyone else touching my bike... Can you change out the spark plug leads or do you have to change out the whole coil if they were fucked?

plugs are ok, i did have it on the 3rd clip position but was a little rich so changed back. brand new plugs in now. when it does spark it is a nice blue, just doesnt seem to fire every time. iv replaced the plug caps and the spark is still the same. just cant get it started at all now, it coughs and carrys on but wont run. cheers for the quick reply, il borrow a multi meter once im home and start checking the wiring.

03 banshee, 3hours on 392cc athena top end. open air box with proflow airfilter, stock carbs with 27.5 pilots and 340 mains, needle in 2nd clip position from top. Was starting and running ok when cold, bit of back firing and popping down low once hot. absolutely no bottom end but excellent once it gets the revs up. thought it was just how banshees were until riding a friends 07 which was very smooth and nicer to ride. half way through a ride and the left cylinder ( main one that backfires) dropped out completely. bike still run, after giving it some throttle in neutral the left fires back up once the revs pick up but drops out again down low. spark seems a little bit erratic/non consistent. I have tried new plugs and nothing has changed, carbs are in sync, i did get an electrical shock through the bars when it was running and i didnt have my glove on, could it possibly be a short somewhere? any help will be appreciated

im interested to hear about the outcome of this, my '03 does the same thing, iv maybe put 5 hours on it since the last rebuild and havnt had a decent ride yet. i was contemplating taking it in to the shop to get the jetting looked at as i have tried everything i have been told to try, never even thought about an electrical problem

as the title states, i have found a set of a-arms and front shocks off a 2011 yfz 450, $450 aussie dollar, including all joints and steering arms plus a set of new rear tyres. Cant seem to even pick up the second hand shocks here for this price but i am limited to workshop equipment, would it take much work to make these fit? will these fit up the same as the thread on here?

yeh i thought about it and opted for the correct ones, dont have time to ride it for the next few weeks anyway...

would anyone know the correct drill size for 27.5 pilot jets? only have a week off and seems they are harder to get a hold of than first thought. iv had one shop offer to drill the standards out to 27.5 for me but hes over an hour away...

is the ez pull setup banshee specific? where abouts would i start looking for something like that?

about 2 weeks ago when i did the top end... i had to push the actuator around by hand to get the cable out and even the actuator arm seemed tight, like flexing and on the verge of bending tight...

heavy enough that i struggle to pull it? iv never had a clutch so stiff on any of my bikes. i agree the suspension needs upgrading, thats definatly on the cards. do u know of any aftermarket heel gaurds? mine were missing when i got it and im not to confident with that gap behind my peg and nerf...

hi, just after a little advice and/or direction. building up my 03 banshee, done the motor now its on to everything else. is anyone running a hydraulic clutch setup? are they any good? my clutch perch/lever setup is really shit and sloppy and want to tidy it up but not sure wat way to go. its currently really heavy too, is that normal? i already have dual stage reed fibres, would it b worth changing over to v-force or rad valves for the $$$? also im currently running a k & n style clamp on filter without an airbox lid, and a noss machine mounting plate, is this an ok setup? bike is currently a 392cc athena top end, fmf sst's with powercore 2 mufflers, stock pilots, 340 mains, at sea level and around 30/35c for the temp. im changing the pilots to either 27.5's or 30's over the next few days once i get home from work as its a pig to start and has absolutley no bottm end whatso ever. any help/advice will be greatly appreciated cheers

Just rebuilt my engine with an athena 392 kit, its got fmf sst's, powercore 2 silencers, noss machine pod filter setup with no lid on the box. Im not quite sure what the pilots are but i stepped up the mains from 280's to 340's with the needles in the second from top position. Bike is a lil hard to start and wont idle, backfires and pops and seems to only run on one cylinder down low and makes about as much power as a peewee 50, then it comes alive up towards the top and kinda gets hard to ride. Its making heaps more top end than before but the missing bottom end kinda makes it no good to ride. Any ideas where i should be looking? They are the stock carbs. Im thinking stepping up the pilots to 30's will this help? Also its a pig to change gears on, i have to granny shift it at the moment otherwise it wont change. Any ideas whats wrong here that might point me in the right direction?

cheers for the help, shes up and running, seems to be holding alright... gotta throw in some 340 mains today and go break it in!!