Jetting for K&N 3 Double filters

[Des Brown]

Help needed for jetting my 1979 1000Z please
I was running last year until I have striped down and done the valves new viton stem seals and new rings
Total rebuild with frame blasted and powder coated.
So all back together now,when I was syncing the carbs I couldn't adjust no 3 as nothing was happening the threads had striped
on the screw,so carbs off and split the carbs and put another screw in I have some spares with collection bits over the years from auto jumbles.
I have always ran the engine slightly rich to stop my pipemaster exhaust from blueing,so while the carbs are off ill check on the jetting.

Whats in the carbs now
I am presuming 35 slow jets
2 turns mixture screw
primary 74
secondary 120
with standard slides and needles
I have also ran this setup with Dyna tune stage 3 needles and drilled slides but got a lot of black smoke on acceleration, the bike came with these on

The jets I have to Hand
6/115s 6/96s 6/98s 6/65 6/100s 6/68s
I use E5 fuel which is 5% ethanol in the UK so I am looking for the best setup of jets and needles
Any advice would be helpful

[steve murdoch icoa #5322]

80 primary, 120 secondary, 35 slow, 2 turns mixture screw with stock needles/slides and K&N pods.
Runs well.

The VAST majority will tell you to return to the stock jetting/filter set-up for optimal performance.

[NobleHops]

I’ve enjoyed several pod-tuned CBXs that generally ran great, were all big-bores too. The gas mileage sucked and they kind-of wanted firm inputs on the throttle, definitely not as dialed as a stock setup, but for a point-and-shoot CBX they are highly entertaining.

[Des Brown]

Thanks for the reply Steve I am hoping to put it back together today but I can wait to
try and get some 80 jets or do you think the 74s will do or will there be much difference
I don't want to go down the stock route as the bike is not standard

[Des Brown]

IMG_1455.JPG

[Larry Zimmer]

Looking good, friend! Enjoy.

[steve murdoch icoa #5322]

Des i can't speak to the the #74 primary as i have only used the #80.

Always liked the look of the gold boomies on a CBX.

[Des Brown]

Cheers Steve
I have ordered some 80 jets so they will come next week so Ill let you know how I get on
I have had the wheels on now for maybe 12 years now the rear 18in are easy to get from a vf750f
the front 18in are a lot harder to get I think I got mine off a CB1100f with vf750f discs and callipers

[daves79x]

I've used the 120/80 set-up with good success also on '79 carbs with pods. I always wanted to try 78s instead of 80s, think it might be just a wee bit crisper, but have not yet. Keep in mind 'good success' does not equal that of the stock airbox and jetting.

Dave

[Des Brown]

Cheers Dave the 120 jets are solex jets as I don't think that should make much difference I hope, the nearest and best price jets I can get are keihin 122.5
it would use a bit more fuel i presume

[daves79x]

I will only stand by my jet size recommendations if they are genuine Keihin. Others are notorious for being incorrectly sized.

Dave