Interesting chewy, as I've got a spaghetti system on mine and running high compression pistons. I've sent Steve Jordan motorcycles in Great Bookham in Surrey a message as he's got a rolling road, for what these carbs cost, albeit 12 years ago from cycleworks, and what I know they're capable of, I feel it'll be money well spent. At the moment I'm doing three quid in petrol to run the bike and fifteen quid in petrol to wash the drive! When I first got them fitted they were good as gold, so this is a recent occurrence resulting from having sat idle for so long. I owe you a drink or a favour for all this advice and help for sure
Looking at your last comment, maybe the float needle is worn. 12 years is a long time and if they are of the rubber type possibly due for a change. i agree with chewy here that it has to be float/needle/seat related. if the carbs were ok for 12 years it is not the angle that is the problem. incidentally, looking at your pics the carb mount angle seems fine. the correct angle is with the acc pump flange level (as yours is near as) then the carb can be swung 45deg from this front to back. you may find that the jetting does need compensation when going from anything but level but not drastically. Also I don't think its the fuel tap not fully turned on as the fuel will find its own level when sat idle, this will only give you a problem at full power for long periods. good luck!
Spike, it's the rubber type - a brass/aluminium body with a conic rubber tip. I'll call the UK importer to see if there is an up issue on the part. The irony is that they've only done 1000 miles if that.
The pump to fit is one of these....much cheaper than demon tweeks to start with....... Facet Posi-Flow Electric Fuel Pump 1 5-4 00psi 60104 - special offer with straight unions As to the fuel level in the tank, I would find / make an adaptor to fit in the original tap thread (I don't think there are any taps that will fit the thread with the right bore....8mm I think) so that a fuel tap from say, a Guzzi, Jap or Brit bike with reserve can be fitted.........The tap will have to be correctly sourced owing to what is below and in the way.......so I reckon a shortish one with a side lever needs to be used.... AL
I think the weight of fuel in the tank can push past the pump and force a dicky needle valve open.........(at least that's what seemed to be happening to mine)..........once it starts, then the siphon effect takes over. The same might happen if the float/fuel levels are wrong, but then that would mean overfilling anyway........but again it could start a siphon effect I suppose....However as the bike runs OK, I am inclined to think the fuel level is OK. If there is a distinct line or tiny ledge around the needle tips then change them. Can you establish if it is running out of both overflows or just one? AL
Can't comment on FCRs but my recent experience of new rubber ended float valves on SUs is that they are a POS, they work for a couple of months then just fail. I reckon they're probably made in China out of old shoes. I'd get the float levels right and fit a solid brass float valve/needle.
Bad news about rubber, it has a life, if only a short one when sat in fuel. i cannot see the fuel syphoning out of the tank, unless of course there is a ridge or mark on the rubber tip, it only needs to be the finest mark and it will dribble. of course if it is/was in good shape it will stand up to 4psi without leaking (well thats the spec). As for the pump i think the original is fine if it is correctly plumbed with the return (without the return it can over pressurise), on bikes with no return i use a pump from an r1, the old mitsubishi type found on carbed bikes (£30ish on ebay). I do like the comment about the old shoes, however dissagree as the quality would be too good. Try allens performance for new needles, they are the uk importer and are a nice helpful bunch.
thanks spike, all the while it sat dormant the fuel was drained out. But I'll get new float needles and go from there. The other option is just to let the dyno station deal with it all, but it still involves getting the thing running to get it there - buggered if I'm paying fifty quid for them to drive it 10 miles.
I set the floats to 9mm, +/- 0.02 but thats the best I can manage. I also took the opportunity to unscrew the main jet and blow that through, and have reset the mixture screws to 1.5 quarter turns. Lets see. I've booked it in with Steve Jordan motorcycles for a full rolling road tune and setup at the end of the month.
If you are thinking of fitting an external Facet pump, you need the 1 - 4 psi version.........the carbed SS pressure is not very high. But FYI, when I was testing the 'blow open' of my float needle valves with a filled float bowl on the OEM Mikunis, I generally saw them burst open at approx 10 - 12 psi. With a return flow fitted to the fuel line, the OEM carbs are basically working as a gravity fed system........In fact, carbs & float needle valves weren't really intended for pressure, just gravity....... The SS has the pump because without it, there isn't a great deal of head unless the tank is fairly full and because the carbs are quite high up........so the pump maintains a constant feed similar to the gravity / pressure of a full tank. AL
Thanks Al, It was more that I was talking with the dave and steve at Allens Performance, and they mentioned that the float needle seats vary for pumped and gravity fed applications. As it is mine had the 2.0 seat so there wasn't a problem in that respect. I've ordered new float needles, seats and also a mixture screw and spring/washer/o-ring as the heads on mine are getting pretty battered. I've got my carb cleaner and airline ready so when they arrive I can just methodically sit down at work, blast it all through and then redo the float setup. Ultimately its still getting its rolling road tune, but I'd like to get it there under my own steam and knowing that the float needles and seats are new.
Dead right, i checked this one out at a tad over 4psi. obviously with no return. On another note, i was in Allens yesterday morn getting some jets and cable nipples, very helpful.
