Trying to get an old 2-cycle Yardman snowthrower running decently. Looking at the engine there are two screws that actually go into the carburetor. Both screws were actually out from 3-1/2 to 4-1/2 turns!! Seems excessive. It was running ..but crappy. Don't know what the screws are, or their approximate correct settings. One screw is on the left nearest the piston. Other on the right nearest the carb intake. But both only about 1/2 inch apart. There is another screw above these that appears to be a mechanical idle speed screw or something else. It goes completely through a narrow aluminum boss, but I can't even tell it does anything (has a spring around it, but it doesn't directly go into the caruretor so don't believe it is mixture related. And I assume a 2-cycle thrower supposed to run at near max rpm anyway?). Turned both screws out about 2 to 2-1/2 turns from seat ....smoothness increased, and so did speed, ..but I don't want to adjust the wrong screw and run the engine too lean. Any ideas on the approximate general 2-cycle settings?
- posted
20 years ago