Starting The Top 80 Engine (Standard Walbro membrane carb).

Important! Do your usual pre-start safety checks.

When the engine is cold (i.e. 1st start of the day) or the fuel exhausted from the tank, the carburation system will require priming.
To enable this there are two devices that you will use, the first is the primer bulb to pump the fuel from the tank to the carb', the second is a hole approx. 10mm in diameter located on the propeller side of the carburettor which provides access to the fuel control valve diaphragm (annotated (B) on the attached picture). Using your fingertip or a blunt object, gently depress the diaphragm which can be seen through the hole, this way when you pump up the fuel it will vent the system of air very easily. Later versions have a button so that you don't have to insert anything into the hole.

Watch for fuel passing through the clear plastic filter located in the fuel line near to the carburettor, as this will warn you that fuel is nearly at the carb. It is important to avoid pumping too much fuel into the carburettor as this will lead to flooding and in severe cases can lead to hydraulically locking up the engine or at best a "kick back" on the pull start handle as the engine fires prematurely and pulls the handle from your hand. As fuel reaches the carburettor you should feel a small movement of the diaphragm, at this point stop priming the system (You will only feel fuel entering the carb if you have a light pressure on the diaphragm, just enough to depress it).

Now move around to the harness side of the machine, apply the choke by pulling the choke activation wire(not all models have a wire, so just use the choke arm) towards the front of the machine and applying approx 5mm of throttle, pull the starter handle, if you have primed the engine correctly then the engine will start and immediately stop.

Sometimes this starting of the engine is just a very easy pull of the rope and you don't always hear it run properly, so if this happens just treat it as though it has run and stopped and return the choke wire to the run position by pushing it back towards the carburettor. That done, then pull the start handle again and the engine should start.

N.B. Some motors will start happily from cold without the use of choke, so try priming and starting without choke, if it starts then you can leave out the choke procedure.

Other tips:

1. Ensure that you are holding the machine firmly with your left hand on the frame above the start handle. Hold the frame to the ground also with your foot on the corner by the fuel tank. This is so that when you pull the start handle you have a hand above it and a foot below and this way the machine will not move when you pull the starting handle.
2. Avoid pulling the rope so strongly that you use its full length. If you do this then you will eventually break the handle, the rope and perhaps the starter mechanism.
3. Use a little squeeze of throttle when starting, by a little I mean move the throttle lever no more than 5mm, just a little pressure, then when the engine starts and runs smoothly, release the pressure to tickover position.
4. Sometimes when the weather is very cold, or the carburettor is set a little too lean, then you may have to repeat the application of the choke. This happens if on the second pull the engine starts and runs but in a short time the engine dies away and stops. So apply the choke, pull the start handle, release the choke and pull the start handle and it should run OK this time.
5. If you have pulled the starting handle 3 or maybe 4 times and the engine hasn't fired or started to run then something isn't right. Stop and think, don't just keep pulling the rope like a lunatic! Have you primed the system correctly, maybe you primed it too much and the engine is flooded. To cure this, holding the machine firmly open the throttle fully and with no choke, attempt to start the engine. If it is flooded then after the 1, 2 or 3 pulls the engine will start, there maybe a lot of smoke and quickly the engine revs will increase so once it has started be ready to quickly reduce the power setting to tickover. Next time watch the fuel going through the filter and feel for the fuel entering the carburettor
6. Maybe though there is not enough fuel. When this happens the engine is a little harder to turn over with the starting handle and sounds dead. Just try priming it a LITTLE more as for the engine to run there must be some fuel in the carburettor and then follow the procedure with the choke etc...