Chris-PA
Where the Wild Things Are
The dual path carbs are pretty simple - take a regular saw carb with a built in choke, open the choke and throttle full and look down the opening. You'll see that the main and idle fuel outlets are all on one side of the plates, and there is a pretty small gap between the choke and throttle plates. I seriously doubt much fuel ends up in the air flow path on the top side of the those plates, but it doesn't matter as they are set up to work that way and both paths mix together after the throttle plate anyway.chris-pa-
this tread got me to looking at the "xtorq" 372. from what i can see in the ipl, it lacks the separate fresh air intakes and has an ordinary looking carb. however the carb is different from the non-strato 372 and its walbro model number has a prefix of "DP" which i assume stands for "dual path." i've never worked on one of these so i'm really just guessing.
also, if the hypothesis, "stratified charge saws don't get enuff oil" was supported by experimental data, the dumpsters would be full of smoked chainsaws. the only data shown here is that davey tree's stihl 362's have a lot of failures and early husky 575 had some crank bearing failures, a problem that was corrected. it's been more than ten years since this technology came to market. you'll have to pry my 575 from my cold, dead hands. and it may kill me because it runs so long on a tank of mix i never get a break.
Now take that carb and add a fin to fill in that small gap between the plates, and feed the outlet into a manifold that is split and has a divider that matches up to the throttle plate when it is open - now the two flow paths are really separated, and one feeds the strato inlet while the other feeds fuel mix into the case.