Hi all I have had a weird problem on my Classic for a while now where it would not come off idle instantly when hot, opposite to our normal problems Anyway I was bored the other night and thought I would strip and fit a carb refurb kit but on removing the petrol tank I noticed that the normal hard vacuum pipe to the fuel tap had been replaced by a black silicon pipe at some time in the past.Just something I had never really looked at or thought about really.At idle where my problem was this is when maximum vacuum is applied to this pipe i.e only on the idle bypass pipes and I found that when hot the silicon pipe was collapsing where it was bent around corners limiting fuel flow, now with the standard pipe fitted from Andover Norton everything is back to normal fault cleared.I think here's an example where a nice flexi hose doesnt work hope this helps someone in the future.
My hard nylon vacuum pipe popped out of the rubber fitting on the inlet manifold and then melted itself to death on the engine. This was coming off the ferry in Dublin for the NW200. Made life pretty tedious through the city centre with a high tick over and a very hot engine. I carry a spare and a small syringe and rubber connector to allow me to drain fuel through the vacuum tap. The syringe is use to apply a little suction to the vacuum pipe and fuel flows. Much better than the manual method.
Anyway I was bored the other night and thought I would strip and fit a carb refurb kit but on removing the petrol tank I noticed that the normal hard vacuum pipe to the fuel tap had been replaced by a black silicon pipe at some time in the past.Just something I had never really looked at or thought about really.At idle where my problem was this is when maximum vacuum is applied to this pipe i.e only on the idle bypass pipes and I found that when hot the silicon pipe was collapsing where it was bent around corners limiting fuel flow, now with the standard pipe fitted from Andover Norton everything is back to normal fault cleared.I think here's an example where a nice flexi hose doesnt work hope this helps someone in the future. 