Thunderbird 900 Carb Refurb

I've posted a few times sorting out various issues with my once reliable and beloved thunderbird 900. Bike was overheating. Fan Switch is fine and I've had the thermostat out, testing it in a saucepan. It might well have been stuck closed as it seemd to stick when i was testing it but seems ok now. Maybe the bike overheating cooked it? Im leaving the thermostat out of the bike for now just to see whether it stops overheating. However I can't test the bike because it's now running like crap, oiling up the right spark plug.

Carbs are a strong possible source of gremlins. Anything else would be worryingly expensive. So I have got em on the bench for a thorough cleaning and a stern talking to.

I've messed about with old 2 stroke outboard carbs many times but this is the first time I have grappled with the Tbirds carbs.

They came out OK. Leaving the throttle cable on the carb and removing it at the grip was a great tip (thanks Carl Rosner Triumph). I had a problem removing the choke cable, seemingly unable to turn the rounded end tube connector out of it's metal mounting point. Embarrassingly i eventually I had to bend the metal surround. Not ideal. If there is a trick to it I'd love to hear about it.

On the bench two of the carbs came apart without issue. The very last screw on the third float bowl is giving me trouble. I'm soaking it with penetrative oil and will have to cut a slot as the cross head has dissolved. I am really hoping not to havr to drill it out. Maybe heat it up with a soldering iron to break the grip?
I assume it is possible to buy new screws, but one thing at a time.

The carbs intakes, where the black plastic vertical gate comes down, looked pretty grubby but the internals look clean. The inside of the float bowls looked clean. I've bought some liquid carb cleaner (as in not a spray can) and will soak everything once disassembled. It was interesting to read that ultrasonic cleaning isn't always the gold standard it seems to be as the liquid does not get into the narrow passages. I'll be using the carb cleaner and forcing liquid into the channels with a syringe.

I was tempted not to touch the idle screw though as I don't want to have to take it to a garage to get it balanced. I know I could count the turns, but perhaps just not touch this part?

I need to take the needle and jet bits apart of course. Are there any issues I should watch out for there?

I need to check the casting tonight to see whether the carbs are mikuni or keihin carb.

What carb kit should I get? I know I should get new gaskets and the little rubber washers. But some kits seem to have needles etc and cost £70 ish.

I guess I'll need to inspect the needles I currently have as I disassemble. Can I eye ball a worn needle and jet?

The carb rubber manifolds that connect from carb to engine block look a bit ropey . Iinternally they seem fine but I guess it makes sense to replace those now.

 

Thanks. Will have a look. I have been watching a few videos e.g. Superbike Surgery. Poor quality gaskets and o rings seem a common issue so Id rather pay a couple of quid more and not have problems in a few months.