Carb Rebuilding Service

I maybe too late in this, but let me chime in about the air box.

Not a KZ, but I have 89' Zx-7. Much more modern then the KZs (but not so modern now................). Back in the dark days of motorcycle, what I wanted to do was to free up the intake (exhaust already came with heavy, but 4-2-1 system) to match the exhaust. I knew from that time that these bikes came little on lean side (I can verify these by looking in the service manual comparing European models with US, specially we got Cal bikes). Bike came with Keihin down-draft type.

At that time, there were plenty of Mikuni's, but I couldn't find any Keihin jets on the island (before ebay, you know.................). Also no email so phone was your best friend, unless you live in the middle of Pacific Ocean. What I was going to do, I'm not sure but I think I was going to modify the stock air box somehow (too long ago to remember anything I might have done or thought).

All I remember is that as soon as the air box came out, just running the carb alone (it did have intake boots with two different length, two longer inner, and two shorter outer. Kept it that way after cutting the air box to retain the boots), bike refuse to rev above 4000 rpm without any load. That means just blipping the throttle, Not actually riding the bike. I tried to put the bike away so got on the bike, just to ride it to back of my apartment, bike didn't even move. As soon as you let the clutch go, bike just died. Had to tape off almost 2/3 or carb opening just to move the bike (I should've just push but I guess I was either lazy or just wanted to see what I needed to do just to move the bike).

So air box is not just piece of plastic design to carry the filter(s). It's pretty important part of whole intake system. So you should run either pod filter ( just mind you it's a whole different beast from not having any air box) or stock air box with filters. Unless you planning to run a set of stacks with net on it ( pretty hardcore if you ask me for a DD) but that's just whole different jetting nightmare (seasonal).

Similar story, that I've repeated previously, but I had an XS400 when back in college. I couldn't afford new OEM air filters, so I bought some cheap UNI pods.  Bike didn't run for crap, regardless of what jets were installed.  The stock air filters, two of them, were located behind the side covers, ducted through soft plastic piping.  I wound up putting the piping back on, but instead of drawing though the OEM filters, I clamped on the UNI's.  After that, the bike ran like a champ.  

Temps finally reached the 50's today, so i got that 6sigma kit installed.
the kit contains 150 main jets, 140 main jets, and shims to raise the needle.
Was a surprise, because i was expecting a complete set of jets...

Either way, bumping up to 150 main, and raising the needles slightly, did make a big improvement.
its now very clear i have an issue an issue with the pilot circuit on the second carb, and i'm still not 100% confident about the sizing of the jets from the keyster kit i used initially.

The info provided with the 6sigma kit lists the following as stock jetting for my 75D
Main: 135  Pilot: 35  Slow: 40  Starter: 72  Primary Air: 60  Secondary Air: 90

The Keyster kit included (as listed on the box)
Main: 135  Main: 60  Slow: 40  Slow: 110

i.imgur.com/ns2fbqk.jpg [/img]
 

These are the kits sold by Z1 enterprises