*Minor Small Engine Maintenance*

Lightweight Tune up

By Eli

20 April 2003


Itís a nice day today so I decided to get the roto tiller running. It still had some old gas in it from last year so the first thing I did was drain the gas tank into a bucket.


Disconnect the fuel hose and drain it into a bucket

Then I commenced to tearing open the carburetor.

Bottom of the carburetor

On the bottom of the carburetor is a flat-headed screw. This is the idle adjustment. Will get to that later. It is inserted into another screw (hollow), which is the one that holds the bowl on.

Use a wrench and remove the screw that holds the bowl. The idling screw remains inserted. Some gas will dribble out. Just have a bucket under it or lay some rags down.

Carburetor float

After the bowl is off youíll see the float. This is what controls the flow of gasoline into the carb. Itís held in place by a small pin. Use caution when you remove it because you might lose the needle valve.

To remove it hold the float and them slide the pin out. The float and needle valve will easily drop out. Reverse process to install it.

This is the bowl

Sediment usually collects in the carburetor bowl. Wipe it out with a rag.

Sorry, it got cut off- Idle screw

Look at the screw that held the bowl on. Inside you will notice a piece of metal with a point. Itís called a needle valve. If it doesnít form a point, itís no good and needs replacement. Same with the other 2 needle valves. Youíll need a carburetor rebuild kitÖ.thatíll be another article.

The big screw is my muffler (needs replacement too). Look at the little flat-headed screw. This is the high-speed adjustment needle valve.

Itís typically located on the side of the carburetor and is the uppermost screw. This lower one (on the bottom of the bowl) is the idling screw.

Once youíve checked and cleaned the parts and have reassembled the carburetor and fuel line.

Put some gas in the tankÖit runs better.

With a flat screw driver, tighten (clockwise) both the idling & high-speed screw. Donít torque down on them, just until they stop.

Back them both off (counterclockwise) 1 ľ turns. Start the engine.

At an idling speed, slightly adjust the idle screw until the engine runs smoothly. Then open the throttle up and slightly adjust the high-speed screw until it runs smoothly. You might have to tweak them both a few times at varying speeds until it runs well.

Thatís all there is to it. It takes some practice, but isnít hard. Go practice on your lawn mower. Works the same way!


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