1981 xj650 info required

another question. the xj650 i have is actually a trike. its running pod filters and tho it starts and runs pretty good, i have noticed it running quite rich from the state of the plugs, also it sounds over-revved at 75mph....showing 7k on tacho (this might be down to tyre/wheel size tho). the jets are standard and the plugs are bp7es. i checked the float heights and they were between 12mm ans 13.5mm, supposed to be 17mm. could this cause the rich running? i was told by the previous owner that its had pod filters for years and he has had no problems as such but he never rode it hard. surely the pod filters would make the engine run leaner rather than rich as there is more air flow or am i being misled by my lack of physics knowledge!!