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babberne,
baileys is having issues with their big bore kits. they tend to give you the wrong sized rings with the kits. most of the time the rings are too small and the saw looses compression and runs verry lean resulting in P/C failure. i just order the right rings. it costs like $10 extra. also you need to let the rings seat. no wide open throttle right after the installation. the best way to beak it in is to let it idle for a bit maybe for an hour or so and then blip the throttle but not wide open. do this for the first 1-2 tanks and you will be fine. my 7900 has a 84cc big bore kit from baileys and it's still going strong today. good luck
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where did you get this info about the rings?? compression has nothing to do with a saw running lean. lean condition has to do with too much oxygen in relation to fuel. it can be caused by incorrect settings on the needles or a leak of some sorts downstream of the carb.
i have run several BBB kits and have read hundreds of other installations. 99% of them run happily without any problem. i have never had a failure. the problems i have seen and read about are related to either plating that didn't go all the way to the top of the cylinder or poorly shaped and ground ports. my first 84cc was returned for the latter reason. there have been some problems with after-market pistons spitting their circlips because either the seat wasn't cut deep enough or the clip was made of cheap metal and lost/didn't have enough tension to keep it in place. but these are not the baileys kits. you have to be careful when you discuss AM P/C kits. there are lots of them sold on ebay that are junk. but the ones sold by baileys, and some other retailers, are pretty well sorted out, and some are actually better than OEM.
the best way to seat rings is by heat cycling. it doesn't take an hour to get the saw to operating temp, and it needs to be done several times. personally, i usually do one or two cycles and then run the saw. i do agree that a saw should not be run WOT immediately when it is first fired up. but that is as true of a new saw as it is of one that is well broken in. both need time for the metals to heat up and expand at their differing rates, and for the surfaces to get a good coating of lube. a new saw should not be run WOT for extended periods until everything has a chance to mate and seat. but, if you think about it, a saw is running at 9-12K rpms, how long does it take for two metals to rub each other down? my experience says that peak compression is achieved in just a couple of tanks. unless you are bucking a large stem, there will be enough variation in cutting speeds to allow the saw to cool down from peak temps. one other thing to remember is that modern carbs
