I recently did a starter valve sync on my niner and found that there was a lot that the service manual left out. i also found that web searching yielded little in the way of good info. after doing it I'm probably gonna check it ever time i have the tank up because it doesn't take long and is beneficial. Here's my attempt at a decent write up that everyone can understand.
warning signs that sync is needed:
-rough idle
-a slight miss sound randomly while riding at a steady speed
-poor throttle response from idle
-uneven coloration on spark plugs when comparing all four
total time: 30-60 minutes
tools needed:
5mm allen wrench
10mm 1/4" drive wrench
10mm 1/4" drive socket
7mm 1/4" drive socket
1/4" drive ratchet
6" 1/4" drive extension
long 45 degree needle nose pliers
4 cylinder mercury or similar vacuum gauge i.e. carbtune , motionpro
large fan
something to prop up gas tank
laptop (for pc3)
5/8" vacuum caps (for pairs system)
prep:
-remove seat
-remove side covers <5mm>
-loosen bolt that is horizontal and keeps tank in place <10mm>
-slide tank bank and raise fully
-support tank with block of wood or something
-remove pairs hoses and cap the plates (skip is pairs system removed)
-remove vacuum hoses from throttle bodys 1 and 4
-remove the vacuum lines closest to center line of bike on 2 and 3 (the outer vacuum lines on 2 and 3 are tied to the fuel pressure regulator and should not be removed)
-remove the 5 way splitter that the aforementioned vacuum hoses are attached to, with the four hoses still hanging off of them
-remove the hoses from 5 way and attach to ends of the leads from the mercury gauge
-install the lead for cylinder 3 first using needle nose pliers
-install all leads from gauge left to right cylinders 1,2,3,4 for easy identification
-hook up laptop to pc3 to monitor idle speed
-set up fan in front of the bike to blow on the radiator
adjustment:
-turn on the fan
-start the motor and let the computer enter open loop. it will run like poo at first but don't worry
-observe levels for each cylinder on the gauge. they all should match cylinder 2 as this is the master starter valve
-allow motor to reach its normal operating temp
-adjust cylinders 1,3,4 as needed by turning the adjustment nuts just behind the mounting bracket for the starter valve linkage. <7mm> (cylinder 2 cannot be adjusted) these nuts will turn by hand with use of the extension. they have notches similar to a rebound damper knob. turn right to lower vacuum and left to raise vacuum. for cylinder 3 i suck the extension and socket between the umbilical cord of wires and the frame.
-make small adjustments and allow system to settle as changes aren't reflected instantly. adjustments also affect the other cylinders slightly so a couple rounds of adjustments may be needed. with some patience you can get all 4 cylinders dead on even with each other
-shut off the motor
reassembly:
-basically just reverse the prep steps to put everything back together (leave laptop hooked up)
-start the motor up again (i didn't need to reset the computer or anything but there may be a stored code that might need cleared at some point)
-adjust idle to 1200rpm +/- 100 rpm
-re-sync throttle position with pc3
-marvel at how smooth it idles
-disconnect laptop
-put on your riding gear
-take it out for a good flogging
-thank me later