running rich

[sean]

here is what I have389 - /239monobloc
                              needle D and pitted badly
                            25 pilot jet
                            106 needle jet
                               slide #3
                            310 main jet
the bike starts and runs but really rich I have checked for obstructions in the intake manifold and gasket the carb is slightly out of round at the flange but I dont see any interference with the gasket in place
I am wondering if having a pitted needle is allowing more fuel to leak into the intake manifold on idle?
seems to be using a huge amont of gas ,black smoke coming from exh,at idle and past,the carb was stripped and all jets cleaned and blown out .
any suggestions .........the choke is fully open  there is quite a bit of slide wear but I would think this would make the mix leaner
forgot to mention 1962 super rocket single carb alloy head

[Butch (cb)]

Pitted needle, worn slide ... time for a new carb?

[Triton Thrasher]

Replace the needle and needle jet with new parts.

What happens when you adjust the idle mixture and idle speed, with the engine fully warm?

[sean]

idle mix control seems to work slows down when screwing in and speeds up when unscrewing I have it about 1.25 turns out seems to idle fine just rich

[bsa-bill]

and speeds up when unscrewing I have it about 1.25 turns out seems to idle fine just rich

idle screw should be adjusted to get fastest/smoothest running, you don't say what happens when you continue unscrewing, it should start to falter again, if so it's good, if not (stays the same) then maybe you need a smaller pilot jet which might help your richness

[muskrat]

 Float height  ????. Float needle  ????
Replace needle & jet.
Cheers

[bikerboy]

This might sound ridiculous (it did to me when it was suggested) but i had a similar problem a few years back.

I cant remember what carb is was but it was on my Super Rocket. Under advise from a mechanic I increased the main jet to a 420. Common sense told me that if I had a bike that was running rich then increasing the main jet was only going to make things worse. Surprisingly increasing the main jet sorted out everything. It ticked over better ran a lot smoother and the plugs were that lovely brownish colour with a black ring around the outside. Even the fuel consumption increased quite noticably.

[bsa-bill]

IIRC 420 is specified for some of the Rockets

Could be explained I suppose by thinking about the venturi/ suction effect over an open tube, like relatively more pressure over a smaller tube - dunno  I think like you I prefer suck it and see to quantum physics

[bikerboy]

Could be explained I suppose by thinking about the venturi/ suction effect over an open tube, like relatively more pressure over a smaller tube - dunno  I think like you I prefer suck it and see to quantum physics
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Thats all to much for me I like things that are VERY simple to understand 

[bsa-bill]

Thats all to much for me I like things that are VERY simple to understand 

Yes me too, I don't think what I typed was what I wanted to say but it was as close as I could get.
OTOH maybe I could have said - Think of the effect when you blow across the top of a bottle, bigger the bottle the lower the tone
or just change the jet and see what happens

[morris]

Could be explained I suppose by thinking about the venturi/ suction effect over an open tube, like relatively more pressure over a smaller tube - dunno  I think like you I prefer suck it and see to quantum physics

shouldn't this rather refer to the needle jet instead of the main jet?

[bsa-bill]

shouldn't this rather refer to the needle jet instead of the main jet?

 

[morris]

Understandable Bill......
that's because quantum physics are more easy to grasp than the workings of an Amal.......