MUD707 Posted May 28, 2008 Share Posted May 28, 2008 I have a 81 XS 400 with bad rings. I tore down the top half of the engine to change them, but the size isn't marked anywhere on them. I was wondering if anyone knew what size the standard piston or rings are. I miked the piston and I am getting 68.8 to 69mm is that the standard or is it oversized? Link to comment Share on other sites More sharing options...
Moderator drewpy Posted May 28, 2008 Moderator Share Posted May 28, 2008 I have a 81 XS 400 with bad rings. I tore down the top half of the engine to change them, but the size isn't marked anywhere on them. I was wondering if anyone knew what size the standard piston or rings are. I miked the piston and I am getting 68.8 to 69mm is that the standard or is it oversized? 69mm is quoted as standard, so iwould assume you are on standard. the overbores go up in .25mm increments Link to comment Share on other sites More sharing options...
MUD707 Posted May 28, 2008 Author Share Posted May 28, 2008 69mm is quoted as standard, so iwould assume you are on standard. the overbores go up in .25mm increments Thanks. Link to comment Share on other sites More sharing options...
yoda Posted May 28, 2008 Share Posted May 28, 2008 You should also check to see if the ring grooves on the pistons has opened up allowing too much ring movement. Link to comment Share on other sites More sharing options...
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