125-200cc 125 exhuast o ring crossover

did a search, nothing came up, checked halls parts fiche, it doesn't give a size ... just says rubber pad. the plan right now is to go down to the yammie dealer and see what a yz o ring looks like. yeah I know I can get it from halls but it would be nice to have friday ...

while we are on the subject of exhuast orings .... I took the current o ring off the stock pipe and put it on the fmf pipe. Of course the fmf is what was on my 125 when it blew up ... hmmm wonder what the bike would run like with the stock pipe back on it. Pull the fmf off remove oring ... note that it is a bit chewed up but not bad ... put it back on the stock pipe .... no way in hell will the pipe go back in. faught with it for 20 minutes .. its like the stock oring swelled up or something. greased it etc etc fugger won't go on. what is up with that?? the inside diameter of the exhuast recepticle is the same, o ring worked on the fmf, came from the stocker, but no longer works on the pipe it came from ... does the heat screw up the rubber??

Check local hardware stores too. My local Ace hardware has a ton of plumbing o-rings that would make fine exhaust seals.