ric h Posted February 13, 2015 Report Share Posted February 13, 2015 Had my Ossa's nikasil cylinder redone by this Quebec company.Cylinder looks better than new.Prompt friendly communication dealing with the clearances needed.$300 (cdn) is better than a new cylinder for sure.I sent them the new piston and buggered cylinder and they came back in 3 weeks. http://www.cvtech-aab.com/en/ Before After Quote Link to comment Share on other sites More sharing options...
johnsandywhite Posted February 13, 2015 Report Share Posted February 13, 2015 Just a point. I don't know whether in this day and age it will be the same? But back in the late 70s and early 80s, we used to have the cylinders done with nikasil after they had seized on our 700 and 750 Yamaha 4 cyclinder 2 stroke sidecar motors. The problem was that they took a LOT of running in to bed them in with new pistons and rings. By which time the rings needed changing again. If you didn't take care running them in, they seized. BUT, the best engine we had was built out of 2 separate non seized but run in 350 twin barrels to make the 700 4 cyclinder. What a motor that was. 1 Quote Link to comment Share on other sites More sharing options...
elemetal Posted February 13, 2015 Report Share Posted February 13, 2015 It doesn't look like the original damage was near the exhaust port, closer to the transfer/intake, is that right? Seems like an odd spot for wear. The work they did looks good, what type of clearance did you leave between the piston and wall? What piston did you use? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted February 13, 2015 Report Share Posted February 13, 2015 What radius have they put on the port edges? those in the photo look very sharp Quote Link to comment Share on other sites More sharing options...
ric h Posted February 14, 2015 Author Report Share Posted February 14, 2015 (edited) It doesn't look like the original damage was near the exhaust port, closer to the transfer/intake, is that right? Seems like an odd spot for wear. The work they did looks good, what type of clearance did you leave between the piston and wall? What piston did you use? The damage was at the intake.I think it was just rough use and maybe a bit too tight.(it's a 2011) I trust CV-Tech know what they are doing.My dealer sent them the factory specs.The piston is a oem 75.95 which is the A.I don't know what the clearances are.Sorry. What radius have they put on the port edges? those in the photo look very sharp The picture doesn't show the radius work they did.Here's a pic that does.It's really well done. Edited February 14, 2015 by ric h Quote Link to comment Share on other sites More sharing options...
copemech Posted February 14, 2015 Report Share Posted February 14, 2015 That original smearing of the piston indicates a seizure or partial. Seems some type thermal event, owner would be the one to say why and when. Did it start rattling? Quote Link to comment Share on other sites More sharing options...
tony27 Posted February 14, 2015 Report Share Posted February 14, 2015 If the piston is 75.95mm then I'm picking bore size will be exactly 76.00mm giving clearance of .05mm or 2 thou Quote Link to comment Share on other sites More sharing options...
ric h Posted February 14, 2015 Author Report Share Posted February 14, 2015 Here is a pic of the piston.It came apart for inspection and to install a second base gasket.The engine was running perfectly! Quote Link to comment Share on other sites More sharing options...
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