As above. I have given the carbs a bit of an overhaul, replacing choke rubber o rings. All pretty clean inside carbs. Starting easier now but still running rich on the right cylinder, spark plug sooty, left side very clean. Checked timing and it seemed accurate.
What should I be checking next?
Make sure both choke cables have a bit of free play when the choke is off or the slides may not drop right down to the bottom. Also well worth oiling the cables up (assuming you have cables and not the flip top type) Are you on the standard air filter or K & N type of thing? Check the airway is nice and clear.Have you got the rubber seals in place on the mixture and tick over screws.Check both needles are in the same slot and you haven’t counted up for one side and down for the other.Clean the carbs again, dismantle the accelerator pump bit inside the brass tube and check everything is clear and moving smoothly and assembled in the correct order.
I presume it has just gone wrong but was OK before? Check choke piston is closing fully, (not tight in cylinder or no cable slack); check the seal thingy in the bottom of it is OK. Also check float not sticking, leaking, swelled so catching on the side(s) of the float chamber, and needle valve actually shuts off the fuel. Simple test is take float bowl off, turn tap on then hold up float, petrol should stop running. Check also the air gallery that feeds the idle system is not blocked. Is idle screw correct, not too far out?
A few things to check then.
It was like this before dismantling. When I found the perished o rings I thought that was the problem.
I assumed needles were correctly setup so didn’t check. Chokes oiled and free play, seemed to work ok. Is there a plastic ball inside these carbs?
There is something inside the little brass bit that goes on the end of the spring, or at least mine has something that rattles around in there, never managed to unscrew the two halves to see what it is. I just make sure it is all clean and clear.
Yes it's a plastic ball. It's a one-way ball valve inside a piston (the "brass bit", lol) which gives a little squirt of petrol when you whack the throttle open. But has to start from below fuel level to be effective though I would have thought. In all the literature I've seen this is called an "atomiser", which I still think is a misleading name. HTH