05.Banshee.SE Posted March 4, 2009 Report Share Posted March 4, 2009 So my bike was reading low compression on my $40 Napa gauge...so I ripped it apart, and the cylinder walls are fine...even still are mirror like finish...the rings look A-ok, just haven't mic'd them... I was asking about piston slap a while back... I have obvious carbon build up from running rich... What gives? Do I need a new top end or not? Quote Link to comment Share on other sites More sharing options...
bansheefreak Posted March 4, 2009 Report Share Posted March 4, 2009 your cyls walls shouldnt look like a mirror should have cross hatches in it.. might be able to just hone it and rering it if bore looks good thou... Quote Link to comment Share on other sites More sharing options...
sredish Posted March 4, 2009 Report Share Posted March 4, 2009 (edited) just because it looks good doesn't mean there's not a loss in compression. if there's a problem in the cylinder then you waited way too long. if all is fine, which is good and means you caught it at the right time, then get some new rings and slap it all back together. if you have a service manual, you can check the specs and mic the piston to make sure it's in spec and measure the cylinder bore to make sure it's in spec. basically from what you've said, get some new rings and get the cylinders honed, slap it together, it should be golden. Edited March 4, 2009 by sredish Quote Link to comment Share on other sites More sharing options...
uwenr Posted March 4, 2009 Report Share Posted March 4, 2009 What kind of fuel are you running? Quote Link to comment Share on other sites More sharing options...
05.Banshee.SE Posted March 4, 2009 Author Report Share Posted March 4, 2009 Yes, there's definately no cross hatching. No gouging...so I guess the bore is fine... There's no literal problems with it, I pulled it apart before anything catastropic happened. Is hone and reringing a better alternative to just doing the whole damn thing? (Keep in mind a fresh bore/hone with all gear for the top end is $300 from HJR...I heard reringing isn't worth it, and just do the whole thing.) Quote Link to comment Share on other sites More sharing options...
05.Banshee.SE Posted March 4, 2009 Author Report Share Posted March 4, 2009 What kind of fuel are you running? 93 octane @ 156 (should be) PSI @ +40'/sea level. It wasn't detonation... I had a boil over incident months ago, which wasn't entirely bad...I still had coolant left... but I was expecting ring damage. The only reasonable cause would be compression loss over time (as your normally would.) Quote Link to comment Share on other sites More sharing options...
magz Posted March 4, 2009 Report Share Posted March 4, 2009 i re-ringed my pistons after i got my passions port job, been running on it for over a year with great compression and am still smacking around 4 strokes daily. i see no problem with re-ringing if everything still in spec Quote Link to comment Share on other sites More sharing options...
sredish Posted March 4, 2009 Report Share Posted March 4, 2009 Yes, there's definately no cross hatching. No gouging...so I guess the bore is fine... There's no literal problems with it, I pulled it apart before anything catastropic happened. Is hone and reringing a better alternative to just doing the whole damn thing? (Keep in mind a fresh bore/hone with all gear for the top end is $300 from HJR...I heard reringing isn't worth it, and just do the whole thing.) don't bore it just for the sake of it, there's only so many you can do and you want it to last forever. if it doesn't need a bore job, don't do it. you can just rering it or if it makes you more comfortable, put new pistons and rings in it, then hone it and reassemble. Quote Link to comment Share on other sites More sharing options...
05.Banshee.SE Posted March 4, 2009 Author Report Share Posted March 4, 2009 don't bore it just for the sake of it, there's only so many you can do and you want it to last forever. if it doesn't need a bore job, don't do it. you can just rering it or if it makes you more comfortable, put new pistons and rings in it, then hone it and reassemble. How does cost relate? I heard "stock banshee piston reringing is expensive so get new pistons" on here somewhere. Quote Link to comment Share on other sites More sharing options...
sredish Posted March 4, 2009 Report Share Posted March 4, 2009 How does cost relate? I heard "stock banshee piston reringing is expensive so get new pistons" on here somewhere. all he needs is 2 packs of yamaha rings, otherwise, a new set of pistons and rings. Quote Link to comment Share on other sites More sharing options...
magz Posted March 4, 2009 Report Share Posted March 4, 2009 all he needs is 2 packs of yamaha rings, otherwise, a new set of pistons and rings. think i paid like 20 bucks for 2 new sets of rings Quote Link to comment Share on other sites More sharing options...
05.Banshee.SE Posted March 4, 2009 Author Report Share Posted March 4, 2009 The front left (inside) nut on the right jug is killing me... Are the circlips the only thing that hold the cyldiners on there? And the local atv guy said something about "loose cylinder"? How would I know if I have a loose cylinder? Is the cross hatching wear, and rings a reasonable cause for compression dropping as low as 90? There's a good number of hours on the top end. Quote Link to comment Share on other sites More sharing options...
Hilarious Posted March 4, 2009 Report Share Posted March 4, 2009 (edited) The front left (inside) nut on the right jug is killing me... Are the circlips the only thing that hold the cyldiners on there? And the local atv guy said something about "loose cylinder"? How would I know if I have a loose cylinder? Is the cross hatching wear, and rings a reasonable cause for compression dropping as low as 90? There's a good number of hours on the top end. the circlips are what keeps the wrist pin in place in the piston. not sure what you mean by loose cylinder. figuratively speaking i think you would know if your cylinders were loose. lol the cross hatching is the pattern that the hone makes in the cylinder wall. if you have a good many hour on your engine, chances are your rings are worn out and yes, you will not have as much compression. also, you can run your fingernail along the top of the bore to see if it catches on the edge. where the piston ring stops near the top of the cylinder it will leave a "ridge". of course the best way to tell cylinder wear would be with a bore gauge. Edited March 4, 2009 by Hilarious Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted March 4, 2009 Report Share Posted March 4, 2009 Maybe im too anal with measurements but its been my experiance that stock bore size wiseco pistons will never give you recommended piston/cylinder clearance in a stock bore.I would suggest going .010 over at the very least to insure tight clearance.Now after you have tight clearance,hone and re-ring all you want.It just seems to me after honing a stock bore lightly there is too much clearance.Yamaha sets there bores up loose from the factory so its harder to cold cease.In my opinion you would gane longer life all around with a bore and pistons,it sucks but not that bad.I used to take all my cylinders to a local guy that charged me 75 a hole now with this website Jeff gets all my machine work,he has done countless sets for me and there allways straight and tight trust me I check everything that comes back, Quote Link to comment Share on other sites More sharing options...
05.Banshee.SE Posted March 7, 2009 Author Report Share Posted March 7, 2009 This fucking inside/left front nut on the right jug is being a huge bitch! It wouldn't budge, so I used lubricants on it, then it stripped...die grided it and it fucking melted into one piece, and I can't cut it any futher without hitting the jugs. This fucking thing!!!!!! Quote Link to comment Share on other sites More sharing options...
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