twin oil circulation

[bjork]

Clive, you may well need to go down on the pilot jet, modern fuels do seem to affect some more than others and as you have a filter as well...
But another problem I found recently with a Monobloc was the damaged pilot jet not seating properly/damaged taper end and fuel leaking around that. New jet fixed it and yes the float/fuel level could do this too.

[clive]

Thanks guys, somewhere I have a plastic window to fit to the monobloc so I can check the level, I think I will start there if I can find it and I might even have a 25 pilot jet in one of the knackered carbs on the shelf.

[SPRIDDLER]

I might even have a 25 pilot jet in one of the knackered carbs on the shelf.

Probably next to the box full of knackered plugs.

[iansoady]

I put it back on without the pilot adjuster fitted and it seem to run well on tickover.

That would suggest a blockage in the pilot air passages as it shouldn't run at all in that state.

[1608]

An unresponsive air screw suggests its blocked.

[clive]

checked the fuel level today, seemed ok but changed float and needle (and yes there are rather a lot of knackered plugs sitting in a box Sprids). Slight improvement but still sooted up after 3 miles tootling around. So back tomorrow and carb off again although last time I could not spot any blockage, presumably it has to be in the air supply to or from the air screw.

[SPRIDDLER]

Try it without the air filter?

[clive]

Did it then too

[clive]

In the absence of an airline I blew through the airscrew with a footpump connected up using the airbed connector. Not much difference so I fitted a 25 pilot jet in the place of the 30. Big improvement but still seems a bit rich but its much better. Is there any risk in going down to 20? (thanks Fred for the Pilot jets)

[1608]

I think just reducing the pilot jet size, although alleviating the symptoms, is the wrong way to go about it. I don't think you can ignore the fact that if the air screw is unresponsive then there is a blockage. Having had a number of bikes with these carbs over the years, as many have, this is a common problem. I make sure that the jet is clear and that a piece of wire will pass up through the jet and into the carb inlet tract. Also made an adaption with an air-bed inflator nozzle and taken it ( with the bike ) to a garage air-line. Try squirting a little carb cleaner or WD 40 into the air-way first.