The Big F Project: I think i'm starting a new habit...

...and I get the feeling that it will be providing this blog with loads of content. What is this new, blossoming habit? engine rebuilds! Finding old, worn out even non-running engines and rebuilding them. Of course I must be quite picky. Some engines, as sad as it makes me to say so are just not worth the effort.

In the case of this first engine rebuild, the Weedeater Barracuda SV-30 was a hand-me-down leaf blower/yard vac. It would not run when I inherited it. After some intrepid dis-assembly (small, 2-cycles are a new realm for me) I discovered a dry-rotted foam air filter had feed some of its crumbs to the minute fuel passages in the carburetor. After the clogs were clear and all was reassembled it ran just fine! It continued to serve faithfully for a year or so.

The other side of the coin... it's always been a chore to start. Also, when I had it apart to clean the carburetor I noticed everything had a heavy layer of caked-on deposits of dust and sludge and oil mist that builds up on any engine or machine that spends most of it's time outdoors. This told me the engine had seen several seasons before even my father-in-law acquired it.

Also, I couldn't help myself. I needed to see the inner workings of a 2-stroke with my own eyes. The idea floated around in my head and when the season for blowing debris from the driveway was over I dug in! here are a few photos of the carnage following the initial tear down.

The core of the blower.

View of the crankshaft and connecting rod in the crankcase through the reed valve portal. Muffler is to the fart right held in place with springs. Inventive!

Various components. Upper left is the flywheel cover/pull-start. The white bottle is the fuel tank. Several gaskets in the lower right corner; carb to reed block, carb to choke plate, reed block to crankcase. Then the heatshield for the carb and some dowel...

The non-engine bits. In other words the blower the engine powers. Scroll housing halves, impeller. The upper left corner of the table is the trigger handle assembly.

Here is the carb and choke plate.

a few close ups:

impeller housing

impeller and mulcher blades

reed block

this is the muffler removed from the cylinder

...the springs hold on the upper half sealing it to the lower half. this is all that keeps the two halves together so once the muffler is removed it is easily cracked open to reveal the inner workings. As some of my previous posting will tell I'm very interested in muffler technology and design. They are taken for granted. A mazed box with two pipes protruding. As simple as most seem when opened, they are quite exacting in their design and construction to perform their job. They must also be cheap to manufacture and provide hours and hours of service with zero maintenance and no loss of performance. NEAT!

Below is the port where the muffler fits. Being a two-stroke this port is in the side of the cylinder wall about midway up the stroke. The black crusty stuff is the carbon build up. Where you can see polished metal is the side of the piston, the semi-circular area being the wrist pin. Notice the small area of the port on the cylinder side compared to the much larger area of the round muffler port. This expansion is very important for the operations of a two-stroke.

A shot of the crankcase sans the cylinder.

Here the cylinder with crankcase gasket and connecting rod protruding.

A close up of the connecting rod bearing. Interesting that it's a needle bearing. In most four stroke engines this is a plain type bearing which works on a film of oil from the crankcase. A two-stroke on the other hand is supplied oil from the oil/fuel mixture. There can be no oil sump because the crankcase of a two-stroke is used to pump the air/fuel mixture into the cylinder for combustion. The image above and below show the grooves or passages that allow this transfer from crankcase to cylinder.