1984 GPZ750 SURGING

Hi All

My 1984 gpz750 has a slight surging problem at approx 3500rpm. I first noticed it in top gear,approx 100-100km/hr,its slight, almost like your backing off on the throttle real slight and then back on again.I dropped it down a gear and ran at the same RPM and it seems the same slight surge exists.
Has anyone else experienced such an issue???? any help would be greatly appreciated. I was thinking it might be the tank vent not allowing the fuel to draw into the carbies quick enough but I'm not sure.

cheers

that can do it being that its an 84 what fuel are you putting into her? and have a look at all vacum lines from the tank to the carbs if there is a leak there will hesitation in the throtle

Cheers for the advice
I'm just using unleaded as it says to, it seems more of a blockage/starving for fuel type feeling. I'll check out the Vacuum lines as you suggest

cheers

There is only 1 vacumn line on those bikes, from the #1 inlet manifold to the fuel tap. If it is old/ perished/cracked, it can suck a bit of air, reducing the vacumn effect on the tap, and this can cause issues with fueling. If you haven't replaced any of the fuel lines - do them all, including the vacumn line.

Regular unleaded should be fine. It won't hurt to throw 1/2 a bottle of Wyns Carbie cleaner into the tank either. This will help remove any gummy deposits in the carbie innards.

Get the carbies balanced ASAP - these old CV Mikuni's are pretty good, but they do go out of synch over time, and a carbie balance can often make a world of difference through the entire rev range.

thanks all for your help, Ill check them out and let you know how it goes
much appreciated