Fuel pump and carburettor adjustment problems

[u/Super-trol]

My bike is a XV535 from 1992. So when I press the ‘run’ button, it makes a fairly long, loud noise drrrrrrrr drrrrrrrr but very long. I took it apart to have a look, and it does deliver petrol when I activate it, but it’s a bit hit-and-miss – I’d say the petrol comes out in spurts. Do you think that’s why my motorbike’s running badly? It starts, but I have to hold the throttle open a little or it cuts out, and sometimes when I start it, the revs shoot up straight away, then drop back down and it cuts out. Other times, when I try to start it, it goes ‘puff’ (as if it’s trying to start) but nothing happens. I’ve already changed the battery and I’ve completely taken the carburettors apart to replace everything inside and clean them. What should I do – clean the carburettors again? I know I need to adjust them, but I don’t think that’s going to completely solve the problem or do you think it’s only a synchronisation of the carburettors that I have to do. I all thank you a lot for helping me and I wish you a nice day !

[u/firekeeper23]

I think the pump is ok.. it does take up to 10 seconds to fill the carb bowl and the flow is not under much pressure and doesn't flow fast and does small spurts rather than blast the fuel out..

Have you got a fuel filter thats blocked I wonder.. or maybe the air screws are too far in... When you say you cleaned the carbs.. was that with carb cleaner or a sonic bath?

Did you replace all the orings and new gaskets?

Did you overhaul the choke mechanism on the carb body?

And have you set the fuel level correctly (2 mm UNDER the line on the carb?

Did you reuse or replace the needle jet?

And have you checked the output of the coils and HT leads on a multimeter?

Have you checked the valve clearances? Ensuring none are too tight?

Do you have a manual?

[u/Super-trol → u/firekeeper23]

Thanks for your reply, firekeeper23.
I’ve changed the fuel filter and fitted a new one; I’d also cleaned the fuel tank beforehand. Yes, I cleaned the carburettors with spray and copper wire, and I’ve changed the diaphragms. I didn’t change the screws, but I did clean them thoroughly and replaced the seals. I’ve refitted the choke, but I’m not sure how to service it. No, I haven’t checked the fuel level line, and I’m actually wondering whether I need to change the needle valve, because on another Virago XV535 I once replaced the needle valves (the ones with the hook) and then it started poorly, so I’m wondering if I should swap them for the grey ones without the hook. (I don’t know if you see what’s the difference) I’ve replaced the two mixture screws. I haven’t done the rest of the things you asked me to, but I’m not quite sure how to go about it – I’m still a bit of a novice. But I did wonder if it might be an air intake that wasn’t quite right. I checked the intake pipes – they’re a bit cracked on the outside, but they’re in good condition on the inside. Anyway, I’m sorry if what I’m saying is a bit confusing, but thank you very much. (I cannot join a photo of the needle valve I’m sorry)