kuelmuel Posted May 17, 2009 Author Report Share Posted May 17, 2009 Thanks for all the help guys. I emailed Birketts, no reply yet. Just about to measure the piston ring end gap, 10 points to whoever guesses the closest as to how many times over the service interval they are. Quote Link to comment Share on other sites More sharing options...
andy.t Posted May 17, 2009 Report Share Posted May 17, 2009 Thanks for all the help guys. I emailed Birketts, no reply yet. Just about to measure the piston ring end gap, 10 points to whoever guesses the closest as to how many times over the service interval they are. If they are anything like the rings that I removed with bits broken off then the gap will be about 1" Quote Link to comment Share on other sites More sharing options...
kuelmuel Posted May 17, 2009 Author Report Share Posted May 17, 2009 I was pleasantly surprise actually, the service limit is 1mm so I expected them to be about 10mm, but they were only 2.5mm! So I've just put it back together again. The piston can twist a bit from side to side but not a huge amount, only about 1-2 degrees either side. I'm sure it'll be fine for a while yet... Quote Link to comment Share on other sites More sharing options...
andy.t Posted May 17, 2009 Report Share Posted May 17, 2009 KuelMuel, you can call me stupid if you like but if the service limit is 1mm and yours are 2.5mm then they are 1.5mm over the limit. Quote Link to comment Share on other sites More sharing options...
tony27 Posted May 18, 2009 Report Share Posted May 18, 2009 Maybe he's light & needs the help in kicking bike over that no compression gives Quote Link to comment Share on other sites More sharing options...
kuelmuel Posted May 18, 2009 Author Report Share Posted May 18, 2009 The compression hasn't dropped from what I can tell. I've asked a couple of guys I know who've had them for years, they both said they've run worse before. To be honest, it definately will need a rebore, new piston, rings, little end, big end and main bearings, and I'll take it out to 270 anyway, so the plan is to just take it easy and if it siezes I'll have to dip into the savings. (Supposed to be for emergancies while I'm at Uni, starting in september). Quote Link to comment Share on other sites More sharing options...
tony27 Posted May 19, 2009 Report Share Posted May 19, 2009 I'll have to admit having owned a 350 years ago with almost no chrome left in the bore which ran fine & still was when I sold it to upgrade a couple of years later Quote Link to comment Share on other sites More sharing options...
kuelmuel Posted May 19, 2009 Author Report Share Posted May 19, 2009 At the moment I have got just about enough spare cash to do the main bearings, seals, big end and little end, but if I'm going to have to get it rebored and a new piston in there then I think I might well do a load more mods to it I've been wanting to do. Shortened inlet, lower and move back the footpegs, extened the rear shock bracket, make another groove on the shock so I can increase the preload, and a few more besides! Quote Link to comment Share on other sites More sharing options...
kuelmuel Posted May 19, 2009 Author Report Share Posted May 19, 2009 (edited) OK just got the top end off, everything is only just within the service limit. Turns out when I shone a torch down the side of the piston I thought the gap was about 2.5mm because it only reflected off the flat side, the tapers that miss the pins in the piston ring grooves didn't reflect any light back. Before long it will need the big end and little end replacing though, they have a tiny bit of twist and up and down play, but my old TY was worse when we rebuilt the engine 4 years ago. Edited May 19, 2009 by KuelMuel Quote Link to comment Share on other sites More sharing options...
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