running to rich

Hello, I am having some issues tuning my 1974 Kawasaki z1 900. I rebuild the cylinder head and adjusted the valves, got the engine bored out to 983cc. Installed a dyna s electronic ignition and dyna 3ohm coils. Also wired up a relay so the coils get battery voltage. Then I rebuild the carbs, new needle and seat, new metring rods, and gaskets. The bike has some kind of 4in to1 header. I also installed an air fuel gauge with a wide band sensor to aid in tuning.
idle is good air fuel ratio is 13-14:1. Wide open throttle is good ratio is 13:1 with 115 main jets. The problem is cruising at 25mph the air/fuel ratio is 10:1 and at 60mph cruising the mixture is 11.5:1.
I have the jet needles set to the leanest position (the clip is in the top groove) The carbs are synced and fuel level has been set precisely with clear vinyl tubing in the bowls to measure height.
I believe the emulsion tube to jet needle clearance is to great but I can't seem to find a replacement anywhere.
Anybody have any ideas where to get these parts? Or should I just get leaner jet needles? The onea in my carbs are stock 5J9.

canadien wrote: ...1974 Kawasaki z1 900...rebuild the carbs, new needle and seat, new metring rods,...
I believe the emulsion tube to jet needle clearance is to great but I can't seem to find a replacement anywhere.
Anybody have any ideas where to get these parts? Or should I just get leaner jet needles? The onea in my carbs are stock 5J9.

What are metring rods?

Perhaps the needle jet in one or more of the carbs has become enlarged (wallowed out) due to wear.

If the carbs have P-8 needle jets, they are listed at Z1Enterprises:
Click here > www.z1enterprises.com/ItemDetails.aspx?i...73%2f74&item=SIK-648

Good Fortune!

I meant the jet needles are new. The needle jet is exactly the part I'm looking for. Thanks for you reply I hadn't found those on there site. THANKS!

Try this site
www.jetsrus.com/a_jets_by_carburetor_typ...ejet_jets_mikuni.htm

The needle "rods" I got with a 26mm kit last year was pure crap. The taper was paper thin point with nothing in common with the original slide needles!!!
If you replaced yours with something like this.... yank them out, junk!!

if you are trying to get close to stoich on cruise, consider that the carbs have no method of power enrichment change. The midrange will be close under load, where you want it to be, but the same throttle opening can also be used for cruise, and will meter the same amount of fuel, so will then show rich. Sure the slides will be at a different opening point but apples to apples, you will have a hard time getting close to stoich in both situations.

My biggest concern is just off idle at 25mph where its running at 10:1 the spark plugs get sooty and the engine isn't running smooth at that speed.

canadien wrote: My biggest concern is just off idle at 25mph where its running at 10:1 the spark plugs get sooty and the engine isn't running smooth at that speed.

The pilot circuits are still significantly influencing the mixture at this throttle position.

Could try leaning the pilot circuits by turning each pilot air screw out counter-clockwise 1/8 turn, and repeat the test with pilot air screws turned out 1/4 turn.

Good Fortune!

The 74 900 came with VM 28 carbs. You have 26's? The pilots should be 17.5. Pics?
Steve

I havevm 28 carbs. pics of the carb, or the needle jet? The needle jet# is 253-O-8. Can't seem to find them anywhere.

What size pilots do you have? The 74 had 20 pilot with a 2.5 throttle cutaway, 5J9-3rd needle and a 112.5 main, stock. Check what your cutaway is.
Steve
The needle jet was a P8.

Mine has 115 main which I installed. I tried a 112.5 a little lean at wide open throttle. My carb slides have a 2.5 mm cutaway. The late 74 carbs have a needle setting of 5J9-2. I am using the 17.5 pilot jets currently.