G'day

The OS LA 46 is a great simple engine which is very suited to trainers.

If the engine is new then it needs a little running in before it will perform to its best. It may be difficult to start in this process.

If it threw a prop, that usually means that the engine had a lean mixture in the cylinder when you tried to turn it over (or a really rich flooded one).

This is what I would do.

1. Put it in a test stand or mount it in a piece of wood with a cut out to fit it. Use 4 nuts and bolts to secure it.
2. Mount a tank behind it so that the centre line of the tank is level with the carby. If it is too high it will flood the engine and if it is too low it will have problems drawing fuel.
3. Put an 11 x 6 prop on it so that when you turn it over anticlockwise (looking from in front of the engine) it comes onto compression with the prop at the quarter past 9 position.
4. With the tank full and connected to the carby, open the needle about three turns. This will be quite rich.
5. With a muffler pressure line from the fuel tank vent connected to the muffler pressure connection, open the carby fully, block the end of the muffler and turn the engine over several times by hand. You should see fuel come up the fuel line to the carby. When the fuel gets to the carby, turn it over a couple more times to prime the engine.
6. Set the throttle so that the carby is open about 1/32 inch or a little more.
7. Turn the engine over by hand to make sure it turns over freely. If it does not, it is flooded. Turn it on its side so that the muffler is lowest and flip the prop back and forth to try to clear the excess fuel into the muffler and drain it out. If you cannot get rid of the excess fuel like this, remove the plug and turn the engine over with the plug out. Be careful putting the plug back. Use your fingers to get the plug started or you may wreck the thread. Do not overtighten. About 1/4 turn after finger tight.
8. Attach a glow plug driver or 1.5 volt battery to the glow plug.
9. Turn the engine over with the starter. If the engine does not fire, it probably is too dry and needs more prime (Step 5). Else, the plug may not be glowing. Check by removing.

Once the engine starts, let it run rich for about a minute and then gradually close the needle. It will need about 10 minutes running before you try to fly it. Leave it tuned a bit rich for the first few flights.

But the best advice I can give you is to find someone who knows about these engines and ask for some real help. A local club is the place to ask.

Cheers

Mike in Oz