I built a version of this for my old Bandit, and used it on my R6 as well, for about 10 years all in. It was all discrete components and worked fine. It went with my R6, so I designed a version 2 to go the gsxs- this one using a cpu (Microchip pic) which adds a bit of flexibility. Pics follow;
The reservoir is an HDPE bottle which goes under the pillion seat. A submersible micropump (TCS micropumps, out of the UK) goes into the bottle, along with associated plumbing. The external hose is the air vent into the bottle, with the pump leads running in it. The unplumbed external fitting leads down to the chain. When rigging the outbound tubing, it should lead up above the level of the bottle with a vent, then downwards to the chain so as to avoid siphoning.
The pump wants 3v or so- a bit less- so the board runs it via a resistor, to prevent overdriving. TCS makes an interesting variety of pumps. My previous design used a self-priming diaphragm pump, I wanted this one to use one of their submersible impeller designs, to reduce the plumbing and hopefully avoid the need for a check valve.
Having a display is one advantage; the leftmost digit shows the count up to the wheel rotation limit in 16ths, so progress of the wheel tick count can be shown. The middle two digits are the wheel limit in hex, meaning from 3 wheel counter ticks up to 255. The rightmost is the pump run-time in seconds from 3 up to 15. The two multiturn pots beneath the display are sampled via the pic's adc to facilitate adjustment. The software computes a running average of 8 samples taken on 100ms intervals, so the least-significant bits are more stable.
Operationally, the box goes under the pillion seat next to the bottle, with the top easily removed to afford adjustment of the pots. I like to get the settings adjusted so after a 30 min ride on the highway no more than 1 drop will fall onto the ground from the chain after a few hours of sitting. Once thats dialed in the only maintenance is checking the bottle's oil level and occasionally cleaning accumulated dirt off the swingarm.
Inputs are accessory power and a 3 wire connection from the ECU's sensor power, rear-wheel rotation sensor, sensor ground. As seen in the schematic, I run the ECU signal thru an optoisolator to a 4020 counter tapped so the pic gets a wheel counter tick at a rate / 256- the wheel sensor is quite high resolution. The only output is a wire pair going to the pump.
When I integrate it in the bike, having the logic in software makes it easy to adjust the tick counter divisions. I certainly could change the 4020 tap also. Once the software is stable I'll burn it onto an OTP device... these eprom chips are great for development but its better leave them in the project box when not in use...
I got the software working properly tonight driven by my signal generator, so its nearly ready to test on the bike- next is to get the board mounted in the project box and the harness finished. I'm using Sumitomo connectors- a number of HM and MT's to spare so it will be nice to use them up. The only big mod on the bike is to tap into the ECU wiring which will be a careful bit of work- the idea being to cut off a short bit of insulation from the given wires, then solder on the leads and re-insulate.