rocketboy Posted May 8, 2005 Report Share Posted May 8, 2005 this reminds me of a condition called a "cold seizure" ,were a stock style cast piston isnt allowed enough time to heat up properly and expand to size, this makes for big ring clearance initally and casues a devastating seizure . another reason to always run wiseco prolites in your machines versus those crude, gross, unreliable stockers Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted May 8, 2005 Report Share Posted May 8, 2005 Rare I know how you feel right about now,I've been there. Quote Link to comment Share on other sites More sharing options...
Rare Scottish Tree Badger Posted May 8, 2005 Author Report Share Posted May 8, 2005 this reminds me of a condition called a "cold seizure" ,were a stock style cast piston isnt allowed enough time to heat up properly and expand to size, this makes for big ring clearance initally and casues a devastating seizure . another reason to always run wiseco prolites in your machines versus those crude, gross, unreliable stockers 366208[/snapback] I think I agree with you here rocketboy on the "cold seizure". Another thing worthy of note is the top ring being closed up inside the groove?? So why did the piston break up into so many pieces? ('cos it wasn't up to temp. ) ... I didn't know they were only standard type pistons in there! With the previous owner having had all the port work done, I don't understand why he didn't put in aftermarket pistons. He also told me the cylinders were on their original bore. Well, they're obviously not as the pistons are marked "25" on the tops. Weiseco prolites on the rebuild! Rare. Quote Link to comment Share on other sites More sharing options...
bansheescotland Posted May 8, 2005 Report Share Posted May 8, 2005 Get the beast ready for Weston i say Quote Link to comment Share on other sites More sharing options...
Rare Scottish Tree Badger Posted May 8, 2005 Author Report Share Posted May 8, 2005 Get the beast ready for Weston i say 366310[/snapback] Welcome to the BansheeHQ Ewan. About time! ... 'Shee better be fixed before October! ... I hope it's done within 3 weeks. Don't want to miss the next MX round at Duns on the 5th June. Rare. Quote Link to comment Share on other sites More sharing options...
Cotton eyed Joe Posted May 9, 2005 Report Share Posted May 9, 2005 When I saw the picture of the piston debris that you got out of your exhaust my exact words were "WHAT THE FUCK??" My wife came over and said "Oh my god." Hope everything works out. Quote Link to comment Share on other sites More sharing options...
tithead Posted May 9, 2005 Report Share Posted May 9, 2005 Get the beast ready for Weston i say 366310[/snapback] welcome to the site ewan! youll enjoy it here. this place is full of laughs and great info. david........ i only saw the piston when i was round and i think my words were "holy shit". now i have seen the rest i have changed my words.... "holy fuggin shit!" i hope stan can do the job..... and get that bad ass mother up and running again! hope everything goes well so we can all have a good time at duns.... if not, before!!!! james. Quote Link to comment Share on other sites More sharing options...
lincster Posted May 9, 2005 Report Share Posted May 9, 2005 this reminds me of a condition called a "cold seizure" ,were a stock style cast piston isnt allowed enough time to heat up properly and expand to size, this makes for big ring clearance initally and casues a devastating seizure . another reason to always run wiseco prolites in your machines versus those crude, gross, unreliable stockers 366208[/snapback] I have had no problems with my stock pistons. Bike is a 99 with all original pistons, bore, rings etc. I still have 140psi of compression. I ride my bike 100% dunes and ride it hard. Runs great. Quote Link to comment Share on other sites More sharing options...
Rare Scottish Tree Badger Posted May 9, 2005 Author Report Share Posted May 9, 2005 I have had no problems with my stock pistons. Bike is a 99 with all original pistons, bore, rings etc. I still have 140psi of compression.I ride my bike 100% dunes and ride it hard. Runs great. 366782[/snapback] I hope you're 'touching wood' as you say that! Don't you think it's time you at least changed the rings and wrist pin bearings? Does what you see above not tempt you to replace your pistons aswell? Rare. Quote Link to comment Share on other sites More sharing options...
lincster Posted May 9, 2005 Report Share Posted May 9, 2005 I hope you're 'touching wood' as you say that! Don't you think it's time you at least changed the rings and wrist pin bearings? Does what you see above not tempt you to replace your pistons aswell? Rare. 366798[/snapback] Why would what your pix show tempt me to start changing stuff? I would never rev a motor to the moon with no load on it. Why would I change stuff when there is nothing telling me to change it? Good compression, plugs look good, bike runs great. I do preventative maintenance, but won't start replacing stuff just because..... Quote Link to comment Share on other sites More sharing options...
Rare Scottish Tree Badger Posted May 9, 2005 Author Report Share Posted May 9, 2005 Why would what your pix show tempt me to start changing stuff? I would never rev a motor to the moon with no load on it. Why would I change stuff when there is nothing telling me to change it? Good compression, plugs look good, bike runs great. I do preventative maintenance, but won't start replacing stuff just because..... 366864[/snapback] Ok, no need to be sarcastic. ... I don't believe that briefly giving the bike full revs with no load was the cause, it should have coped with it. But doing that when not up to temperature probably WAS. It's not something I would usually do and like I said, I have been so frustrated with my sticking slides that I thought I had cured that problem and wanted to check. I was just too impatient. ... "My stupid fault". I don't wish bad luck on you, but 6 years on original rings is asking for trouble. ... Rings wear, and to me, changing them periodically is 'preventative maintenance'. Rare. Quote Link to comment Share on other sites More sharing options...
SANDSTAR Posted May 9, 2005 Report Share Posted May 9, 2005 DAMN I guess I shouldn't have mentioned "piston skirt". Sorry for the jinx. Thats ALOT of chit to pour outa your motor. Never seen one literally BLOW UP like that! Quote Link to comment Share on other sites More sharing options...
SANDSTAR Posted May 9, 2005 Report Share Posted May 9, 2005 If you need to resleeve, I have 2 stock pistons/ rings you can have if you pay freight. Quote Link to comment Share on other sites More sharing options...
Rare Scottish Tree Badger Posted May 9, 2005 Author Report Share Posted May 9, 2005 (edited) Stock pistons. ... Never again! But thanks for the offer, SANDSTAR. ... I'm getting Wiseco Prolites. I spoke to my Engine Tuner/Porter today (Stan Stevens, UK) and I've to send out my barrels, what's left of the piston, the other piston, and cylinder head tomorrow. I'm hoping he'll be able to work on the two damaged (transfer) ports and tidy up the bore. ... Failing that, it'll need a new sleeve, port matching, and re-bore. Rare. Edited May 9, 2005 by Rare Scottish Tree Badger Quote Link to comment Share on other sites More sharing options...
PUSH THE THROTTLE Posted May 9, 2005 Report Share Posted May 9, 2005 I have had no problems with my stock pistons. Bike is a 99 with all original pistons, bore, rings etc. I still have 140psi of compression.I ride my bike 100% dunes and ride it hard. Runs great. 366782[/snapback] Sounds like you got a better set of pistons and cylinders out of Yamaha than most people. Six year old bike with 140 psi is pretty good, what was your starting compression with that cool head? Quote Link to comment Share on other sites More sharing options...
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