carb jetting

i have a 78 kz1000 z1r...has new vance and hines header...race series baffle....stock ncarbs...does anyone have a jetting spec generally for this set up...also has a 1087 kit just done....seems to have stumble off idle and has surging sensation at cruise freeway speed... seems to be too lean overall...cold start painfull...takes choke for overly long time...any help would be appreciated....

Usually when changing to a free flowing exhaust and when increasing bore size you now have a bigger demand for fuel than the stock set up. Your off idle stumble is more than likely the needles in your carb slides need to be moved up one clip which will richen your off idle response. While riding on the freeway type speeds your carbs are on the Pilot circuit and sounds like it is running lean there also. Usually a good starting point is to increase your pilot jet and main jet size by 2. I have a 79 MK11 AND WHEN I ADDED A 4 INTO 1 and pod filters I increased my mains from 110 to 115 and my pilot jets from 15 to 20 and my set up runs great.I believe your carbs are 102.5 mains and 15 pilots.I would double check those numbers and rejet accordingly. I am no expert but did suffer some of the problems you described.P.S running your bike leaned out can cause overheating and engine damage espeacially when overbored. Hope this helps. Grant.

Welcome...

Could be a simple as a needle lift, or not.

Do you have pod filters , or stock airbox/filter...?

You will get the best/smoothest performance from that machine with a proper jetkit, with different needle tapers.

They need to bring on more fuel early, but not too much across the midrange.

Just raising the needle can cause the stumble to just move around sometimes.

GL.

i got both messages and will take apart and see what is there... re-jet accordingly and let ya know..thanks for the help...noone i no has anynidea about the old bikes....thanks again...troy