I bounced between lean and rich , but it's right there on the money now , the jets sizes so close I can call the optimum by chosing the middle ....
I've put a summary below.
1998 VZ800 Modified to Stage 3
The pilot system required no modification , and at time of writing, no reason to displace the (new) needles E-clip either up or down from the middle position, could be found.
Presentation of "Before" and "After" performance curves provides defining and valid proof of the performance gain.
Test Bike :
Vin JS1AF111500100405 , series VZ800"V" ,assumed 1998, 7th owner or more !
Engine Number S506125843
Odometer Approx. 21 000km
Altitude: Coast , 10m MSL
Conditions: 15-25 deg C , Cape Town , sunny South Africa
Bone stock , Full-Throttle switch found and remained connected , no "PAIR" system existed , the 98 model is characterized by the rear cylinder header routed around the base of the engine, and not around the back of the cylinder. The only departure from OEM original was a pair of exhaust end cans with internal dia of the baffle tubes in the order of dia 24mm , through-flow. The 'before' run was compromised, by one of these baffles getting lost en route to the dyno. As the stock clutch was already showing signs of slippage , the clutch was disassembled, the steel plates deglazed with 800 grit waterpaper , new OEM friction plates where installed , but the original springs were replaced with high performance Vezrah units , SK329 , a very common fix. Lever effort is obviously increased. A wise man very accurately sets the valve clearances about now !!! Engine oil was Putoline 20W50 mineral , used generally for hot summers , 10W40 is prefered for winter and the recommended viscosity grade by Suzuki.
After the "before" condition was dyno'ed , I had two new 38mm core baffles hand made , which became therefore, part of the "After" condition variables. This could have had a small influence on the main jet selection, but by < 5 'units' , is my guess.
K&N filters, 1 of RU0680 for the front , 1 of RA0470 for the rear , which includes a plastic elbow
Mikuni Carb Needles 2 of , both "5DP7"
Vezrah Clutch Springs SK329, & Suzuki clutch cover gasket 11482-48E01
Mikuni Main Jets ... depending on baffles diameter mainly, recommended, almost certainly optimum, or very close start point ... 142 front , 145 rear
A roughly 12mm slice of any old 2" ( 50mm ) PVC pipe fitting , to fit in the front filter mouth...from your pool shop, plumbing supplies, or shed.
A new or good condition 2.5mm drill bit
It is assumed you are competent and have a little experience , essentially, get the carbs loose and free but keep the cables attached, extract the airboxes and bid them farewell by recycling what you can. Replace them with the air filters , but I recommend you first bend the old mount tab on the right side of the frame at the front, out of the way of the new front filter, or it will chafe it. You will lose the cable securing mount for the same reason, carefully applied cable ties will do the same job. Loose the metal tab or it will chafe the filter.
The rear filter and it's elbow punnched through the rubber, can accommodate the old crankcase vent piple, with thought. Not quite positive crankcase ventilation like before , but better than being open to atmosphere.
Open the carb bowls , if you are smart , use "Hexagrip" on a clean screwdriver ...it increases the friction between tool and screw head by some 500%...you may need this, they are tight, install the 142 on the front (replace the 90), the 145 (replace the 100) on the back, close up. If you don't have Hexagrip , try course valve lapping paste.
Open the carb tops , remove the 5C29 (F) and 5D27 (R) original needles, note very carefully what you are doing, and the orientation of the retainer plates ! Drill both slides vacuum holes to 2.5mm all the way through. Only a little material is removed, this is correct
Install the E-clips on the middle slot of the 5 slots , of the new 5DP7 needles , ( thank you Grant STL over in the USA ! )
Now, be very, very attentive ! Needle pointed sharp end down ...E clip in the middle slot....push the plastic spacer up from the bottom so it's now UNDER, not over, the E-clip !!! Then the small metal washer, then the spring.
You now have, from top to bottom, e-clip, plastic spacer, metal washer, spring. Yes, nothing UNDER the e-clip has any effect on the needle height ! But it does STABILISE the needle in the slide. Put the needle in the slide, replace the retaining plate to push it all down, make sure the needle is centred, and tends to snap back to centre if displaced to the side. Are you SURE ? It's free yet self-centering? Yes ?
Replace the carbs with care , be very careful with the choke cable, you will see what I mean.
The slice of PVC pipe fitting should make an ideal internal re-inforcement INSIDE the front K&N mouth , so you can clamp the link pipe firmly ... you will understand when you see how it needs to be employed.
With the bike painstakingly assembled , the carbs sync'ed , and the idle mixtures dialed in , you are done.
It should ride without missing a beat , behave like a stock bike off idle at part throttle , then accelerate like a bat outta hell at larger throttle openings.
The honk of those open airfilters will let you know you're now riding a very modified beast , you'll get used to it in time.
Be warned, it will most time wheelspin in 1st given a heavy hand ...