EPA Regs
I won`t share all the details with you because frankly I don`t clearly remember them, but I do know this much. The EPA mandated that saw manufacturers had to meet certain emissions standards with all models by a certain date, I think it was sometime in 2002. At any rate, a variety of factors affect exhaust emissions and some models could be made compliant with non field tunable carbs while others such as the Husky 272 couldn`t be, and they went the way of the dinosaurs. From what I understand, the EPA did not stipulate that carburators could not be tunable by a "qualified" mechanic, hence limiter caps on the screws of Jonsereds and Huskies, but I would say that Stihl saw an opportunity to make some bucks on replacement carbs since the EPA had shut down their income from selling replacements for lean siezed saws. I understand that Stihl has even gone so far as to purchasing the "rights" and tooling to certain models of Zama carbs that these models are sporting so that you can only buy a replacement through them. I am not a carb expert so I can`t speak with authority, but I have been told by a long time Stihl chainsaw mechanic that there are some instances where a carb has to be replaced because a particle or obstruction is stuck in an orifice that is no longer accessable, due to unique size welsh plugs placed deeply in the orifice. It is also his opinion that a lean sieze could also be the result of such obstructions in a saw used by someone who is not always fully aware of proper operation, such as a typical homeowner who uses the saw once a year and leaves the stale gas in it from year to year. The Husky limiters are simple to remove for tuning so I expect the Jonsereds are the same. In some cases you have to replace them because there is no longer a spring to hold the screw adjustment, and they are required to be replaced by law if a dealer ever removes them or sees that they are missing when your saw goes in for service. I`m sure this will get only more restrictive with time so it might not be a bad idea to save the carbs off those old rocked out saws if they can be crossed to a new model you use. Russ
