I'm running a very standard 998 with hs2 carb and struggling with what I think is a fueling issue.
On the road, the car runs pretty well. It revs ok and pulls cleanly enough from low down. However, at tickover it chugs badly, puffs black smoke and generally seems to be running very rich. Plugs are very sooty. If I sit at the lights too long, or don't get going quickly enough in the morning, it fouls the plugs.
I've tried leaning out the main jet to the point where it starts to misbehave, but even then it seems choked up at tickover, puffing black smoke.
I would welcome any other thoughts, but at the moment I'm taking an interest in float height. According to the late, lamented Mr Haynes, I should have an 8mm gap between float and lid. Mine is much lower, more like about 5.5. Because this difference is measured quite close to the needle, this would make a significant difference to the float height. I have a couple of other, junky hs2 carbs and they seemed about the same as the one I've got in there.
The floats are solid plastic - no brass tang to bend. It seems I have to adjust float height by putting a washer under the base of the needle valve? I've tried putting a washer made from 0.4mm gasket material under there, raising the height to roughly 7mm, and I think it's slightly better, although I could be kidding myself.
Anyone got experience of these solid plastic floats, and able to say what the correct height should be? Or any other thoughts about what else I should look at?
Thanks in advance...