The pump and rotor to the right is the main lube pump and the one to the left is the scavenge pump, as far as I can see this pump acts like a dry sump pump by controlling the oil level in the engine and storing it possibly in the gearbox? The main pump feeds from the gearbox through the little thimble shaped strainer so this would make sense. Im kinda thinking this through while I write this so I hope it all makes some sense.
So more oil, the scavenge pump is the same diameter, rotor size and shaft size as the main pump but 5mm wider, I'm asuming that will mean it can pump more. I have thought about this a lot, mostly through last summer, I was busy with other stuff and not home to work on the bike so I was mostly studying the manual and pictures of the crankcases, clutch cover and oil pumps. The idea then was also to put the bigger rotor in somehow, I was thinking along the lines of milling back into the crankcase to make a recess for the wider pump to sit in. I eventually gave up on that plan as it kept throwing so much problems up. Even lately I had a new plan, the KLX c is built without a kicker unlike the R, the space could house an oil pump? I got a zxr750 pump off eBay so I could get an idea of the physical size of that pump. That still might be do-able if all else fails. I did consider driving a gear pump off one of the cams but it's not as neat as a in crankcase solution.
So latest version, and to me the least time and effort for hopefully a good result. The bigger rotor goes in the pump (normally a 7mm rotor, now going to be a 12mm scavenge rotor) making the pump 5mm wider. The scavenge pump will still be there and is driven off the outboard end of the oil pump shaft, so the whole clutch cover will have to go out 5mm too, a second gasket and an aluminium packer plate cut out on a waterjet bed should do for that. The clutch release rod would have to be made longer, also I could put an extra steel and friction plate in the clutch, coincidentally they add up to 5mm thick, so that's two possible ways to achieve that. The oil feed to the crankshaft and the piston and bigend lubrication goes through the end of the end of the crankshaft and to there from drillings in the clutch cover so the lip seal that seals around there would have to be shifted back inboard 5mm by an adaptor turned out of aluminium I think. The drive to the oil pump and the waterpump would have to go out, possibly not all of 5mm, 4 or 3.5 might do, it will still be enough contact with the gears to drive it surely. Oh and the oil pump itself, I will make a new shaft for it, 5mm longer than the original, the gear looks to be shrunk/pressed on so that will be pressed off and pressed on the new shaft.
All this should be reversible in the event of it being a flop. But I intend to run some tests so I can say, yes it's more or damn I wasted my time on that scheme.
I got a loom with the last motor I got and enough electrics to run an engine off the bike so I'm going to set up a test engine to try it out.
