Im renewing the fuel lines on my 900SS 1994 (carb model) and adding a cut off valve (manual type) to the fuel line between the Y piece and the carbs, but what is the story with the item #32 in the attached picture, it seems to be a sort of flow restrictor to the return fuel line. Is it really needed and if so what can I use if the original part isnt available? Thanks Ps. For information I found a 'Sytec' low pressure fuel pump suitable for carbed bikes for fitting inside the tank for about £40 (new, inc the gauze filter) on ebay
The jet, or restrictor was put in the return line to ensure the flow of fuel always went to the carbs as a priority rather than loop around the feed line and directly back to the tank. The feed to the carbs offers route of least resistance until the float needles close, fuel can then follow the return line.
Thanks, it sounds like pretty much anything will do to reduce the inner diameter of the return pipe "a bit" relative to the pipe feeding the carbs, meaning the carbs will get 'priority'. Does anyone know the size of what they're calling the 'jet' required to restrict the retuirn flow the right amount ..... are we talking a big restriction to return flow or not?
The 900ss I had didn't have one and got on fine without it. It is there to provide a slight positive pressure to carbs. The Pasos 750 and 906 had a similar arrangement and some owners have fitted a carb jet. I don't know what size but I imagine it would be pretty big. If you have too much pressure the float needle will have difficulty closing.
As Derek mentions, there are loads running without one nowadays. There is a reduction of sorts on the return line at the union on the tank. The internal pipe is also smaller than the hose which is probably why it works without.
The only reason you would consider trying the O.E.M. restrictor is if you were using it on a 400 or 350 (38 Mikuni still) or with aftermarket Keihin carburettors, and this would be as a last resort, in an attempt to help with persistent flooding.
Thanks Chris, but I do have 38mm Mikunis (38 BDST) on my 1994 900SS - they were standard fitment on my model (and also the 750SS from that era I think) so are you saying I should be using a restrictor or not? Pete
