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Clearing air out of fuel lines explanation?


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Unfortunately I don't have any prior experience with two-stroke motors and I'm a little bit confused on how they work, especially about the procedure where you clear air out of the fuel lines.

It's a ROS 125 motor with membrane / Walbro carburetor (I'm not sure how the latter works, but it appears to pump fuel into its fuel chamber and then the engine's combustion chamber via the flex of two trampoline-like rubber-ish membranes and a network of one-way valves). Leanness / Richness can be adjusted through two screws that terminate into needle valves?

So... if I see air in the line, I'm supposed to put my finger into this hole/depression on the side of the carburetor, squeeze the primer fuel bulb until... sometime..., tip the engine over on its side to drain excess fuel into the air filter, and then there is a hole at the bottom of the air filter box that drains the fuel out onto the ground?

- Ok, ok, what does putting my finger into the hole/depression do? 

- correct me if I'm wrong. I'm supposed to:

  • Prime the engine by squeezing the bulb... once? That sprays fuel directly into the combustion chamber of the engine.
  • I make sure the compression release is engaged
  • I yank the starter cable which spins the flywheel, compresses the fuel and air from the priming step, and sets off the spark plug. Is the point of this step to get the engine turning above a certain RPM?
  • Hopefully the engine then starts running on its own. 
  • I warm up the engine and set it to full throttle at least one time while on the ground to make sure bubbles are out of the fuel line
Edited by fuzzybabybunny
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Just read your post again  . Re the hole / depression , when pressed lighty squeeze the primer bulb if you have transparent fuel 

pipe you'll see the fuel and any air bubbles on its way to your carb , squeeze the bulb till there gone  ' you'll prolly have fuel dripping out by now . That's it your ready to start .  If your fuel tube is black stuff ' one more squeeze on the primer bulb after you see fuel dripping.    Try it .

cas . 

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