These Mikuni RS40-D1-K RS carbs will breath a whole new lease of life into your machine with around a 25% increase in power, whilst making it perform and operate as it should.
You will very quickly realize that the expense of a rebuild of your old worn OEM carbs can far exceed the cost of these new units and also unfortunately as with many rebuilds now days you only have the option in many cases of gambling with very poor quality aftermarket parts. Considering this and if intending to ride and enjoy your motorcycle it makes good sense to retire your OEM carbs into the cupboard and step up to a set of Mikuni RS’s.
Before rushing in and ordering please firstly check your carb spacing and carbie sizes for compatibility. These are not suited for downdraft engines.
This Mikuni RS kit comes with the following carb centre to centre spacings for direct fitment to GSX-R ’90, Kawasaki KZ and other Race engines
A= 77mm (spacing centre to centre between carb 1 & 2)
B= 93 (carb 2 & 3) see note below if different
C=77mm (carb 3 & 4)
If the centre spacing between the centres of your carbs #2 and 3 is 85mm, rather than the as supplied 93mm, two of the outside carbs will need to be unbolted and then slid in so as to align with the second set of provided securing points and then re-fixed. Due to limited demand for these carbs to suit 86-87 Yamaha FJ 1100 and 1200 engines along with some other applications with the 85mm centre measurement the factory no longer markets them assembled in this configuration thus requiring you the end user to make the adjustment and then re-synchronize the slides.
The OD at the motor end on 40’s is 44mm
OD at the air-cleaner end is 55mm
Front to back length is 100mm
Pilot Jet: VM28/486-17.5, Needle: 9CHY3, Needle Jet: Y-6 (568 Series), Main Jet: N100.604-140
We have twin throttle and cable assemblies available
Velocity stacks which have no form of filter in them (15, 30,50 and 75mm long) for racing