About 6 months ago I was able to get a reading from my timing light. I just tried to check the timing this last weekend and all I get is an intermittent flash if anything. If I bump the gas I get a normal flash(during the rev), but with no way of actually checking the timing. It is not a cheap timing light. I have the carbs adjusted as best as I can. Can it be the 8mm wires? Which is the conductor for the timing light. Or possibly a weak coil? Only mods are: 2 1/2 pipes, glass pack, muffler, 8mm wires and ngk spark plugs. Any ideas of why it won't register with the light?