My 78 Z650d (sr) is hitting a flat spot midrange. It happens in all gears but because i have no Rev counter my only point of reference is I hit the flat spot between 55-65mph in 5th (the highest gear)..I can pull out of the flat spot with a wide open throttle and after that she shoots forward…but then it also happens around 70mph when rolling off the throttle. It also happens less when winding on the throttle Gently, might hit the flat spot at 60 rather than 55…

She’s got vm24 mikuni carbs with standard main and pilot jets, but I’m using generic pod filters and a Harris 4>1 exhaust.

I know with those mods I need bigger jet sizes and I was thinking 3 up on the main and one up on the pilot (that’s based on hours and hours of thrawling through z sites)..it was also recommended that I try two sizes up on the mains and leave the pilot alone, which k was up for trying but I was reading least night that if the idle isn’t smooth, or doesn’t come back down, and the exhaust pops when coming off the throttle I need a bigger pilot jet? Which brings me back to 3 up on mains and one up on pilot? 110 mains and 17.5 pilot? I think the standard is 102.5 mains and 15 pilot. And leaving the needle on 4th groove and airscrews as Is.

Anyone a genius with carbs or do these mods on their own bikes have any experience of playing with jetting?

Cheers!:thumbsup2: