The manual goes into the tuning process, but it does miss one point...

That is not only do you need to tune the engine, but you also need to perform a nose up and nose down tuning test as well.

e.g.

With 1/2 a tank of fuel but no more...

Tune up the engine, so that it runs at MAX RPM's at WOT, then back it down about 3 clicks. The engine should slow down slightly.

Still at WOT, pinch the fuel line for a second ( no more ) you should hear the engine briefly speed up a bit then go back to where it was before.

If so, point the nose up. Again the engine should or might speed up, but it should NOT quit.

Adjust it so that it doesn't quit when pointed nose up at WOT.

Once done, point it nose down about 25-30 degrees.

The engine will slow down a bit, but again it should not quit.

If it does quit check for air in the fuel lines. If there is air the clunk was uncovered during the nose down test, and you may have to re-test with more fuel in the tank.

Make sure that the engine does not quit at WOT nose down.


Now bring it back to idle and adjust the bleed screw.

On the LA you need to UNSCREW ( open ) the bleed screw to lean out the engine.

I find it impossible to get the low end TOO lean, and usually it remains way too rich no matter what you do.

Perform a PINCH test... but this time pinch the line off longer.

The engine should continue to run for 2-3 seconds and speed up as it does so before cutting out.

If it runs for more than 3-4 seconds it's too rich.

If it stops immediately it's too lean.

Now peform a nose up and nose down idle test. In either position the engine should not quit.

Finally leave the engine on the ground at idle for about 5-6 minutes.

The engine should not slow down or cut out.

If it slows down it may still be too rich... ( typical for the O.S. LA's though... ).