Setting the float height:
First and foremost, set the float height correctly before you start diving way too deep into fuel head pressure/intake signal stuff. Remember the KISS theory Keep It Simple Stupid.
So, on your delorto......Which is probably pretty close the same delorto on my 2001 501. Let's talk about the function of the fuel inlet needle and seat. First examine with a magnifying glass the needle. The little sythetic rubber point should have no flaws whatsoever. If there is any question at all replace both the needle and seat. Now, the needle. If you will notice, there is a little plunger in the center of the needle that rides on the float arm. You will also notice that this little plunger has a spring in it. This is to take up the gyrations and sloshing of the fuel in the bowl during riding.
Now, to set the float height, which by the way has nothing to do with the actual floats themselves, but, rather the arm that the float rides on.
With the float bowl off and the float arm and needle and seat installed. Hold the carb upside down, and at a 45 degree angle with the float arms pointing down. You will see that the center of the float arm is what is in contact with the fuel inlet needle plunger. At this point you can lightly push on the float arm to see the action that the spring loaded plunger has. The reason that we are holding the carb upside down and at a 45 degree angle is so that we can see the float arm in contact with the plunger on the fuel inlet needle, and, this is most important, to make sure we are not compressing the fuel inlet needle plunger spring.
Now that you are holding the carb in this fashion, the long float arms should be parallel to the flange that the float bowl seats against. If the long float arms are pointing towards the flange, the float level will be too high, and would/could cause excessive fuel enrichment, IE flooding. If the long float arms are pointing away from the flange the float level is too low and would cause fuel pick up problems for the pilot circuit. Which in theory could give you a big flat spot as you are opening the throttle and transitioning from the pilot circuit to the needle circuit, as the intake signal starts to drop off.
I found on my deloroto shod 94 & 1/2 501 that the float level was way off, (lean or too low) which contributed to hard starting problems. Sometimes a huge impact can bend this adjustment, but, I think if that happened the float level would be the least of your worries. More likely would be that it was not set correctly during assembly.
And as another post said quite correctly: "If you raise your idle too much, the intake signal at start up will be weak and make it hard to start". This is also very important. All three of my Husaberg's have been very easy starters when hot, or cold. You just have to get it set up right.
So as with most mechanical things, make sure the float level is set correctly before starting any jetting changes. Otherwise you could end up chasing your tail and never catch it.
If you have the need, don't hesitate to give me a call. 818-383-6035.
P.S. Make sure that the long float arms are parallel with each other. And there is one other thing. Make sure one of the floats doesn't have a hole in it. To check this leave them submereged in fuel, then take them out wipe them off and shake them indivually. You'll either hear the fuel sloshing inside, or you will see a lttle wet spot where the leak is.
