Eccentric
Mister Wizard
Eccentric;
I think I have this down, but could you fill me in on the pyramid reed valve?
What I see on the newer XL12's is a block with the pyramid shaped reed valve, that has the carb sitting farther back. It also comes out with the carb when you rebuild it.
The earlier ones have the carb sitting right up against the housing, with a verticle reed valve.
Have I got that right? Also, what does this do for the RPM's and about when did this change take place?
You've got it. I don't know what year the changes took place. It was probably gradual, and not the same year for every model series. I'll have to ask my Homelite-nut friend. The pyramid reed blocks have two or more reeds (depending on model, for example 1050s have four, 2100s have six) giving a larger valve area (and thus more flow) than the single reed of the non-pyramid type. I can't remember how many reeds a pyramid Super-XL12 or Super-XL130 has as it's been years since I've had one of those saws apart. If you have an exploded view of the pyramid reed block equipped Super-XL12 you should be able to see the number of reeds. My Homelite-nut friend swaps pyramid reed blocks into some of his older saws for more power.