Float needle valve

[xenia1]

Sticking float needle valve- n.o.s carb from the 50's. Will fire up and run fine but if left for a while when the fuel tap is turned on the carb floods and sicks all over the floor.
A car/truck mechanic i am (was) but scooter/bike grease monkey im not Obviously i dont want to go ruining the tip of the needle as there are no replacements but what to clean it with? 2000grit wet and dry, metal polish? Carb has been dismantled and cleaned with carb cleaner.
Any help appreciated- Andy.

[Captain Pugwash]

If the tip is swelling because of the modern fuels its in contact with then I'm not sure what you can do about it, but if it's just a build up of small deposits in the valve seat and on the rubber tip then maybe using an ultrasonic bath with the correct cleaning fluid might help.

Ive only just Bought my own ultrsonic cleaner and found if it's used with the correct carburettor parts cleaning fluid it seems to work on most carb parts without damaging anything, it's also very good on any other engine parts.

Good luck, Mark.

[Scooter Paul]

Is it a non soft tipped nose? If so I think something like Solvol Autosol on the tip and then twiddle it in the hole, varying the direction, like grinding in 4 stroke valves should help. I've done this before and it worked. However if the carb body has corroded so badly you'll never get a seal you may have to resort to more drastic engineering. You are looking for the taper of the valve needle to match exactly the seat taper. That's why soft tipped noses became the norm. They give more tolerance in the seal. But as said before older soft tips are ruined by ethanol.

Paul

[xenia1]

Thanks for the replies Mark, Paul.
Its a soft tipped (black coated) valve and the carb being nos is perfect condition. Will try an ultrasonic clean and see if that improves it although i cant physically see any kind of deposit or residue..

[Scooter Paul]

Black tips are non ethanol proof. So if this is all you can get use fuel stabiliser. Have you contacted Delorto UK. They are very helpful. Often non available Lambretta parts can be cross referenced straight from Delorto. Parts for carbs can be common across different manufacturers of machines. As to deposits causing poor sealing it really doesn't take much and hard to see with the naked eye.

Paul

[xenia1]

Ah...didnt know this type wasnt ethanol proof and probably here lies the problem. Will see if a replacement valve is available.
Thanks to you both for your help.

Andy.

Ps- another thing thats crossed my mind is timing. My Tv1 is supposed to be at 26 degrees but thinking with modern fuel this could be adjusted somewhat.
Whats your opinion ?