Ruko Posted January 3, 2004 Report Share Posted January 3, 2004 Has anyone else had this problem and does anyone know how to avoid doing it again?? OK here's the story. I was riding along no problems and started losing power. Checked the exhaust and it was missing on one side. Went home and did a compression test, I had 120 and 65. Not good, but not a big deal yet. Pulled it all apart and the little pin in the top ring groove that is suppose to keep the ring from turning was worn right off. So the ring turned in the groove until the end hooked the edge of the exhaust port and broke off. Didn't do much damage so I got away with a hone and new pistons. When I took it into the local shop to get it honed the guy said he had never seen that pin wear off like that so we figured this was a fluke one time deal. Within six months two of my buddies have had the exact same thing happen so we are starting to think this is no fluke. It happened with two stock pistons and one Wiesco. So I got a few questions. Has anyone else had this happen?? Is this a common problem?? If so what causes it?? And how do you prevent it?? Thanks Quote Link to comment Share on other sites More sharing options...
Big Blue Posted January 3, 2004 Report Share Posted January 3, 2004 have you bored your cylinders yet, it sounds like you may have some piston slop (not sure what to call it) but it may be rocking in the cylinders if this is the case it may not be to long until you catch a skirt in the exhaust port. My buddie had this happen not to long ago. Quote Link to comment Share on other sites More sharing options...
Ruko Posted January 3, 2004 Author Report Share Posted January 3, 2004 Mine was an 01 with stock bore and stock piston. The bores were still good enough to just hone them and reuse them. The next one was an 03 with stock bore and piston, and again it was OK to reuse with just a hone. The last was a 96 with .020 over wiesco pistons. It put a pretty good groove in the cyl. so he is having it rebored. This last one just happened a couple weeks ago so he hasn't got it fixed yet but the cyl's are out getting bored right now. When mine happened it was all stock with T5 pipes. Quote Link to comment Share on other sites More sharing options...
blk02banshee Posted January 4, 2004 Report Share Posted January 4, 2004 maybe too much or too little ring end gap? Quote Link to comment Share on other sites More sharing options...
spoin39 Posted January 4, 2004 Report Share Posted January 4, 2004 Make sure you "file fit" your ring gaps to make sure you have the best seal. Quote Link to comment Share on other sites More sharing options...
Ruko Posted January 5, 2004 Author Report Share Posted January 5, 2004 The two stock engines had never been apart. They were stock out of the box from Yamaha. If this was a Yamaha ring problem you would think it would be more common. There has not been any responce that anyone else has had this happen so I am starting to think it must be something that we did. The three of us ride together all the time and all three of our machines did the same thing. Unfortunatly we don't know how to prevent it if we don't know what caused it. All your help is appreciated Thanks again Quote Link to comment Share on other sites More sharing options...
spoin39 Posted January 5, 2004 Report Share Posted January 5, 2004 What premix oil do you use and at what ratio? Quote Link to comment Share on other sites More sharing options...
Ruko Posted January 5, 2004 Author Report Share Posted January 5, 2004 When the first two did it we were using Opti-2 synthetic. It says to mix it a 100-1 but we were mixing it at about 58-1. We have since changed to Amsol 2000 just because a friend of ours is a dealer for it. We are now mixing it at 50-1 as it says on the bottle. The third was running on Amsol when it happaned. There was no wear or scuffing on any of the good pistons to indicate a lack of lubrication, so I think the mix was OK. Quote Link to comment Share on other sites More sharing options...
Patriot Racing Posted January 8, 2004 Report Share Posted January 8, 2004 The ring end locating pin can work loose from a sloppy bore. The piston rattles in the bore and causes the pin to walk out. Did they mike out the piston clearance with the worn pistons or just mike the bore and install new pistons? Id wouldnt be suprised to have seen a piston clearance of .006 or greater. Quote Link to comment Share on other sites More sharing options...
Oilsmoke Posted January 8, 2004 Report Share Posted January 8, 2004 Dan what amount of piston clearance is needed for a Wiseco Pro lites? Quote Link to comment Share on other sites More sharing options...
PassionRE Posted January 8, 2004 Report Share Posted January 8, 2004 The locator pins can walk out even on properly set-up clearances. Wiseco had huge problems with this back in the late 70's and early 80's. Its a manufacturing problem mostly, although sloppy clearances cant help in the least....Jim Quote Link to comment Share on other sites More sharing options...
Ruko Posted January 9, 2004 Author Report Share Posted January 9, 2004 Unfortunately we did not check the clearance on the old pistons just on the new ones. But the pin did not come loose and come out. On the stock pistons the pin is on the top side of the groove with the bottom half of the pin into the groove and the top half above it. The pin stayed in place but the bottom half was worn flat to allow the ring to turn. The Wiesco pin was also still there but the end was worn off. Is this the same problem of too much clearance?? If so how much clearance is too much?? Quote Link to comment Share on other sites More sharing options...
SDD Posted January 9, 2004 Report Share Posted January 9, 2004 You might want to have a shop check your bore for roundness. Sometimes a cylinder will distort when hot or when torqued down. Quote Link to comment Share on other sites More sharing options...
Patriot Racing Posted January 10, 2004 Report Share Posted January 10, 2004 Oilsmoke .003 for most motors in a fresh bore. Ruko- old worn out parts then- just too much time on those pistons. Id be interested to see the rings themselves- as you have ran such a lean oil ratio, I think the ring wear was accelerated. You all ran the same mix correct???? Ive never torn down an blown engine from too much premix oil!!!!!!!!!!!!!!! Quote Link to comment Share on other sites More sharing options...
Oilsmoke Posted January 10, 2004 Report Share Posted January 10, 2004 Thx Dan for the info. Quote Link to comment Share on other sites More sharing options...
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