VM 29 Smoothbore Air Mixture Screw Setting?

Ok I just received my 120 mains, 17.5 pilots and will install them tonite. I also think my air mixture screws are off a little. Should I start at 1/2 turn out from closed or different? I still have the Kerker Competition Baffle in. Bike runs good now but it pops a little upon down shifting. Not sure I will ever stop that with the current baffle. Previous experience with a similar set up I was never able to make it stop...Russ

want to get led by the blind...here goers...un-burned fuel entering our headers explodes ...making the pop...i'm sure you know that...but just in case thats the simplest explanation i've heard????
i have the same jets on 29 smbr and pods and opened(lot of disks)supertrapp...stock motor....
i believe george told my to start a 1 1/4 turns from lightly seated mix screws....i'm sure he'll chime in soon...
was i a good student????we'll see...best of luck russ.....
p.s once after i used really fine wires to clean my carbs tiny passages in the jets (in bowl of c.cleaner)i had the best non popping carbs...they pulled clean and hard and returned to a nice idle.....eventually they went knida back to a popping a tiny bit on hard downshifts too!!!
i cleaned em last week to try and fix that sputter(coil wire) and now they seem to pop a slight bit more....who knows.....best of luck bro....craig...1 1/4 turns????

Here's the link to carb info on Z1E website.
Mikuni 29mm Smoothbores]

The charts for various carbs include the following:

29mm smoothbores Z1 / KZ900 / KZ1000
Main Jet 120
Air Jet 0.9
Needle Jet O-6
Jet Needle 5DL31-3
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 17.5 or 20.0 (or 25 in the later versions)
Air Screw setting 1 1/2 turns out


As I recall, some folks have derived improved fine tuning with richer air screw settings (meaning lesser turn out whereby the air is diminished).

I start with 1 1/2 turns out from lightly seated, and go from there.

Remember to assure correct service fuel level in float bowls via clear tube test (and not rely on the upside down on the bench measuring method).

Good Luck!

it definitly sounds like your a bit lean down low try those stock settings and i bet your problem will go away.

Air screw should be somewhere from lightly seated to 1/4 turn out. Tune each carb for highest idle speed. If no difference can be heard in this range, leave the screw at about 1/8 turn out from lightly seated. The air screws 1 1/2 turns out as has been suggested will be very lean with #17.5 pilot jets.

Well I think I have figured out the solution to my SMOOTHBORE dilemma.

pjmotorsports.com/Jets%20Pics/expvm29.gif

Part # 19 on this exploded view of this fine carburetor the starter screw which attaches to the starter lifter was not completly in the groove of the shaft starter causing carb #4 to depress the starter plunger slightly to deep into the carb. Thus causing undesireable bogging and poor throttle. It would idle fine but at around 3800 rpm it would bog till 5000 or so. These are very tempermental carbs and I am sure many have thrown in the towell in the past. On the bright side tommorow in Ohio it will be 70 degrees and route 35 and 68 have my name on them. The competition baffle in my Kerker has attracted a few neighbors the past couple days as some of them have been coming by to watch as I have been tinkering in the early evenings. They also dont mind the free beer in my fridge. Performance is important but would it be wise to have a stock set of carbs around for general crusing or do these carbs remain pretty reliable once dialed in?...Russ

29's go from pilot to main..... and thats it. Popping sounds lean to me. Go up on the pilots, minimum of 20. Are you runing an air box or pods ?

arai59 wrote:

29's go from pilot to main..... and thats it. Popping sounds lean to me. Go up on the pilots, minimum of 20. Are you runing an air box or pods ?

Pods today air box tommorow...Russ