Some years ago, in a fit of pique, I acquired a set of split FCR 41's 2nd hand. I'm now in the process of getting the 900 back on the road after it was laid up for a few years. The FCR's came with the blue plastic velocity stacks. I'm looking to fit either the air box with K&N filter or to fit pods. To do this, I need the intake stubs and seal are there any recommendations about a supplier? Apart from fitting an electronic fuel shutoff to circumvent the needle valves wearing and leaking, is there any advice on how to run the fuel delivery/return circuits to the fuel tank? Thanks in advance. Martin
I bought mine from Chris at CCW many moons ago and they had adapters very like these but in ally, there is a small lip and flange where you can install either the rubbers for the airbox or a set of pods - I have done both. Used to run them on the long manifolds and an airbox with a K&N & open top. However now I have split them and am running short inlets & pods on the same bellmouths. I'd go with something like this if you're gonna delete the airbox or if not just get the ally adapters, not sure I'd trust someone's 3D plastic jobbies from ebay tbh. https://www.frankmxparts.com/KN-luc...arburateurs-Ducati-750-900-SuperSport-Monster The leaks are normally from debris keeping the float needles from properly sealing and the fuel then siphons from the tank - not from the valves wearing, I'd hope you'd service the carbs before that. No need for an electronic cutoff as the main feed is by a pump just make sure your tank is scrupulously clean and fule delivered well filtered. I'd just copycat the standard system, ensuring you put back the restrictor in the return line to have an ever so slightly elevated pressure at the float needles when the pump is running (4.2mm ID IIRC).
@mcr998 I have the banked 41mm, theyve been in the bike for years, so I have some experience of the issues. I had the engine get hydrolocked with fuel, as the float needles got jammed open due to something. I would absolutely fit a fuel tap, I switch it on and off everytime I ride the bike. I had an electronic one, but when it rained it got into the connections, so I went back to manual. The fuel lines just need to be copied from the standard, which has a Y shaped connector, with a restrictor on the return, I think mines the standard piping from memory. They are awesome carbs, split ones give better top end over the banked, which give a little more torque.
I have the split FCR41s on my Monster and as it would be near impossible to use an airbox due to the layout, I originally tried the blue stacks and foam 'sock' filters over them but when on the dyno, the filters took away around 6-7hp IIRC and you really can't run them open (like my old Guzzi) as the vertical cylinder carb intake is directly behind the front wheel. I bought some K&N stacks which are designed to fit K&N filters and they are a much better option as the foam socks wouldn't fare well on the vertical cylinder where the front of the filter faces the front wheel and so will get battered with debris. I made a long heatsink/deflector plate for the reg/rec that acts as a mount/heatsink for the reg/rec, a shield for said filter and also to deflect air to the rear cylinder for better cooling which seems to do the job of keeping the filter clean but the K&N filter has a rubber front anyway so doesn't get too battered as would the sock filter. K&N stack; With filter; Available direct from K&N along with the filters, note I have a straight filter on the vertical cylinder carb but needed a lightly angled filter for the horizontal cylinder carb as it points upward under the tank and needed to clear the frame rail & battery box - I did also modify the frame to better fit the carbs as they wouldn't fit right with the short Malossi intake manifolds. Also, I have an Ignitech ignition which has programmable advance but found that the timing jumped around a bit based on RPM only - not helped by light flywheel/lumpy idle so I fitted a TPS to one of the carbs so that could be incorporated into the ignition map and the throttle is much less on/off than before, making it much smoother to ride especially in town/city traffic but still very much 'on' when required. Though this may not be an issue if you are using the original ignition setup? TPS fitted to vertical cylinder carb; For fuel return, I have a later EFI tank with internal electric pump that, simply pumps fuel through a loop, returning to the tank with a 'Y' connector take off to a 'T' connector to the 2 carbs and it's been working great for the last 15 years. As for fuel shut-off, FCRs don't like too much fuel pressure so a return is a good idea and some means of shutting the fuel off when not running to prevent the carb flooding (if float valves stick) and filling the engine with fuel and for this I fitted an electric fuel shut-off valve from the 'Y' to the carbs that is only open when ignition on (has a manual over-ride in case the solenoid fails). In all, I did a lot of work to get my setup to fit but mine was a custom nut/bolt rebuild, to make something 'special' (to me anyway) and it maybe simpler if you don't go quite as OTT.
Hi Neil66, thanks for the information. Did you find much difference between the different air intakes. The parts from Frankmxparts seem to be out of stock, but I've added a notification address for when they come in/
This installation is potentially going to be the basis for my set up, as I remember you posting the progress on this on the forum.
If you're using the Malossi short manifolds (same one for both carbs) then I don't think you'll get any kind of airbox to work due to the horizontal cylinder carb (vertically mounted) having it's intake way back and high up. Mine is a Monster so the frame is different but with that setup it wouldn't fit with the standard frame layout. I had to move the crossmember (in front of the battery) back to get the horizontal cyl carb to fit and also the diagonal brace forward to get the vertical cyl carb to fit and even then I needed to machine a few mm off the alloy adapter from carb to manifold (cut off the first 'ridge' to use the second) to get the vertical cylinder carb to clear said diagonal. A banked setup is a much simpler installation. But I think the SS frame has a bit more space in there so should be easier?
