alanhugs

Hi there, I bought an old (1982) XJ750 a few months back, which I have been fixing up. She has got nearly 80000km on the clock. Currently I have problems with the way she is running: She starts ok, idles a little unevenly, but rides away ok. As she warms up, literally after 2 or 3km, she develops a "flat spot" at lowish revs (2000 to 2500 rpm). This gets worse and worse as she warms up, till (after 8 or 9km) I have very little power at anything under 3000 to 35000rpm, making slow riding almost impossible. She feels really flat as I try and accelerate, and then a surge of power as the revs gets over 3000rpm. She sounds fine at higher revs. And if I stall her I can not get her to restart. Oh and she didn't have this problem when I got her, she had other things wrong with her, but was not doing this... I changed oil, air filter and plugs when I bought her. The new plugs have some carbon now, so guess she runs a bit rich. I suspected the carbs, so took them out and cleaned out the float bowls. Haven't balanced the carbs yet (as I don't have vacume guages). If anyone else has had these symptoms, or knows how to go about solving it, I would be very grateful. Thank you from a newbie on this site, Alan.