TOPIC:

I'm about to install a set of 29mm carbs on my 1976 kz900. What i want to know what is a good starting point for pilot jets and main jets and any other adjustments. Will I need to install a high flow petcock?

The bike currently has Dyna S ignition and wires, K&N pod filters and 4 into 1 exhaust. Everything else engine wise is stock.

tom

Did you check to see what jets are in them now? Assuming they are used I'd never trust them to be stock.

#120 mains would be a good start. The pilot jets depend on which slide cut out is used on the assembly.

no i haven't checked. these carbs have been sitting on my workbench for a few months and just haven't had the time to check. I was planning on giving the carbs a good cleaning and test ride this weekend.

900 are usually 17.5/117.5

oldkaw79 wrote:

900 are usually 17.5/117.5

I have the 117.5 jets in my 26mm carbs and they are dead on.

The VM29s that fit a KZ900 were originally sold for a KZ/Z1 OR a GS750/850/1000. The slide cut out for the Suzuki version is much bigger and requires a MUCH BIGGER pilot jet. Since these carbs have fussy pilot circuits, you had best know which version of the assmembly you have by checking the slide to see which cut out is installed as they are identical otherwise. Since the 29s are fundamentally a different carb with different internals than a VM26, the jetting for a VM26 isn't going to help much.

what size is for the kawasaki and what size is for the suzuki?

Are these "smooth-bores"? I thought all Mikuni 29mm were! If they are, then the pilot jets will be a different configuration (length & size) than the usual Mikuni's, hence, not interchangeable. Whereas, the mains are common.
RegardZ.

Mikuni uses five basic types of pilot jets. The first is the early Z1 style. I don't have a clue what the Mikuni nomenclature is but the 73/74 Z1/Z1A carbs are the only one that pilot jet fits. The second is the style used in a VM26/28 series (includes Z1B and 73-80 900/1000 models as well as many GS VM26 models) and it is called a VM28/486, the third is the 22/210 which are used in all VM24 and VM29. The fourth is the BS30/96 which are used in BS (constant velocity) carbs as well as the carbs on a Venture and possibly other later Mikuni carbs (don't know all that much about newer aftermarket varieties) and last is the Mikuni N151.067 jet needles which look the same as the BS30/96 except don't have holes in the sides like the BS30/96 pilot jets do. The N151.067 are used pretty much interchangeably without noticeable performance effect is the BS series carbs.

When you say "normal" pilot jets, Garn, I stock all of them because I use all of them.

The slide cut outs for a Kaw VM29 are 1.5 and Suzuki 2.5.

I run 17.5 and 117 in my 1075. Roy

Then you have the Kaw version of the VM29 for sure Roy. The bike wouldn't even begin to idle if you had the 2.5 cut outs. Those things start at about #22.5 pilots. You could probably go a bit bigger on the main jets as well... what does it do over 7K rpm?