1984 GPZ750 SURGING

[leep]

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

[bigkevbusa]

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

[leep]

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

[Gosling1]

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.

[leep]

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