Hi mate a bit late in the day but may help some one I learnt this trick when I was 7 years old.
If a motor isnt starting
a. Pull the plugs. Turn the engine over see that there is a bright spark at each plug.
b. before puling the plugs try starting the engine with the choke on. So when you pull the plugs look to see if they are wet with gas they should be.to wet and your flooding too dry and your not geting gas in.
This would eliminate your Gas or spark issue.
All this talk of shims do I take it the valves arent adjustable then.
when you say 'Turns pilot screw fit in 1/4 turn', what exactly do you mean? that you can only turn them in 1/4 turn (meaning the screws are only 1/4 turn out), or that you turned them in 1/4 turn? if the screws are only 1/4 turn out from all the way in, that's a bit too lean.
you don't need a timing lamp for anything, the ignition timing is electronically controlled.
try turning the pilot screws all the way in until they stop, and then turn them all the way out 2 turns. this way, you know exactly where you're at in terms of pilot mixture......if you just turn them in without knowing where they were to begin with, it won't really help much....
is the bike running rich, though? did the plugs come out very dark?
i don't know the exact float height for your bike, although a fairly good rule of thumb is to set them so that the 'lip' on the floats is parallel with the float bowl mating surface as the tangs on the floats just touch the float valves. (your mileage may vary, though)