Need some jetting suggestions.

I've got a 76 900 with a 1015 kit (supposedely), web 110 cams, dyna S ignition and grn coils, Emgo pod filters, a MAC 4 into 1, and it had some original Mikuni VM 26's that someone did a home port job on???. I don't think they had any idea what they were doing (they looked pretty tore up) so I bought a set of unmolested 26's off ebay and cleaned them up and am going to try and use them instead. I've got the original 115 mains and 17.5 pilots in it right now. The old carbs had the needles set with clips on the very top (highest). Should I start off with the clips in the middle with the new carbs and do I need to change any of the other jets right off the bat because of the other mods. Just not sure where to start.

It wasn't running when I started. I did get it to fire up but I am waiting on some plug wires and I need to swap a couple of valve shims out before I mess with the carb some more.

Maybe somebody who has done it before will chime in, but if not here's what I might try:

Look up the stock jets for it, I suspect they are the 115 and 17.5 you have because those are the ones I remember. Mac headers are not known for great flow characteristics. Add pods and you might want to start with one size larger on the pilot and two sizes up on the mains, which would be 20 and 120. I would set the needles to the center notch for starters.

Bear in mind that's just a guess.

bountyhunter wrote:

Maybe somebody who has done it before will chime in, but if not here's what I might try:

Look up the stock jets for it, I suspect they are the 115 and 17.5 you have because those are the ones I remember. Mac headers are not known for great flow characteristics. Add pods and you might want to start with one size larger on the pilot and two sizes up on the mains, which would be 20 and 120. I would set the needles to the center notch for starters.

Bear in mind that's just a guess.

i m no carb guru, but that sounds like an excellent place to start...if you have to adj from there, it wont take much...keith

Am I reading this correctly "it had some original Mikuni VM 26's that someone did a home port job on" where they ported the carbs and not the head ports? :blink:

As Bounty mentioned, start with what you have (OEM stock jets), ride her and see where she presently lies in performance, throttle response, spark plug insulation and ring color, how does she idle, response in low-med-high rpm ranges etc...

Even with new Keihins, pods, 4-1 exhaust, head P&P you pretty much end up with 2 jet size changes on the Mains and pilots... A clip position here & there... It's been pretty much the same for all of us....

But keep in mind, all motors are different, intakes, vaccum pull, manifold no leaks, exhaust no leaks, head P&P, valve seal conditions and of course carb synch etc....

Then of course, whats the true condition of these 30 year old carbs of yours... You are rebuilding them with carb kits while you have them out right...

What worked for our motors may not work for you.... Close yes but dead on... no...

Thanks for the advice. I hope to get it running Mon when the coil wires show. I still need to finish the valves and probably degree the cams since it's got adjustable spockets and I have no idea where the original owner set them or how.

The "home port job" looked like someones attempt at turning their set of 26's into a set of "29's". They took a dremel and removed material in front and behind the slides. On the back they actually flared them to a point where they meet the boot. They actually didn't do too bad for doing it by hand but there's no way they are right like this. I've seen this done before but you need to set them up on a machining center to do it right. I'm not even sure if these are good carbs to do this to in the first place.

I have torn the old carbs apart soaked and rebuilt them but just with the jets I alread have. They cleaned up pretty good.

I have another question I'll post in the engines forum about the web cams. The clearance varies quite a bit when you rotate them long before they begin to open or close. Makes it hard to decide what shims to use. Go by the smallest gap?? I've never run into any cams that were grouknd that "unround" on the back of the lobes.

Thanks again for the replies.

With the 110 web-cams the 26mm carbs will be drastically restricting your airflow. You should have bought 28s instead. Even those would be too lame for a set of cams that potent. A set of BS34 CV carbs would have been the best and cheapest choice for that motor.

I might have to look into that once I get it running a little better. Got the 26's for next to nothing so I just thought I'd start with them. They used to use them on the 77 1000 but with the cam you are probably right.

It sucks waiting for something as simple as a couple of shims and plug wires. I went an tried some local places but nothing is open today.

The 77 1000 had the same cams as your 76 900 only 100cc more displacement. Out of all of the Kawasaki bikes the 77 and 78 KZ1000A/B were the biggest waste. I don't know what Kawasaki was thinking when they did those engine arrangements. The only thing that made more sense was the 78 Z1R.