Where can I get a float needles / rebuild kit?

The Long Story:
(Might help someone in future)

So the first attempt just doing it by eye was crap, idled way too high. Second attempt I bought some better verniers and measured from the center hole to the outer edges and tried to match it the whole way around, that took about 3 hours and seemed to be going well. I just kept filing it bit by bit, eyeing it up and filing as necessary. Seemed to be going well and I almost had it sealed the whole around around, but when I reinstalled it alongside the other 3 carbs I found it was too small in the vertical dimension and there wasn't enough adjustment to allow it to close properly, hence massive air gap. Big /sigh as I threw it away and started again

Third attempt I decided to do it a bit differently. I firstly took the assumption that the bolt holes were wrong (and sure enough upon very careful measurement, they were slightly off center still)
I measured the diameter of one of the original butterfly valves in both the horizontal and vertical dimensions. Mine read 25.95mm horizontally, and 26.90mm vertically
I filed the top, bottom, left and right edges of one of the templates down so that measured about 26.00 and 26.96mm respectively. This left 4 flat edges which turned out to quite useful actually. I inserted the new one into a carb, sure enough it was a very tight fit but they went in. I proceeded to remove and file the corners of each edge until it allowed me to rotate the butterfly valve enough to get a good look at the bolt holes, and YES the bolt holes were off center about half a millimeter. So I enlarged them with a round file in the appropriate direction so the bolts wouldn't cause it to skew off center

Then I attempted to measure and file the valve around the edges to get the same diameter but this proved to be insanely difficult and time consuming. And it's very hard to know how much to file each half, if I do too much on one side and not enough on the other, the dimensions might match but it'll be off center and leak air in the carby. After thinking about it for a bit I decided to use this method


1) Place the 'NEW' butterfly valve in the calipers, starting horizontally. Make it snug and then tighten down the locking screw so it just sits there by itself
2) Place the 'OLD' butterfly valve on top of the new one and see if there's any wiggle at all side to side. If there is, check the position of the bolt holes (so as to know which side is off center, or if both are about equal). Undo locking screw, remove the old one and file the appropriate side, or both equally if unsure. Repeat this step until its a snug fit
3) Put the OLD butterfly back in the calipers, rotate it 20 degrees or so then use the locking screw to lock it in place. Place the new butterfly on top of the old one 'horizontally'. It'll be a loose fit, this is fine. Rotate it until it becomes snug. It won't rotate as much because it's a larger diameter.
4) Remove it, file it slowly and recheck until it can rotate and the bolt holes line up.

I kept doing that and then just periodically checked that there was a smooth and consistent increase in diameter around it. I got it within a bees dick of the original, installed it back into the carb and checked. Still a decent gap, but it was quite clear where the high spots where. I just kept removing it, filing down the high spots and re-checking. Being sure NOT to file the very top, bottom, left or right edges (as I checked they were spot on before). Took quite a while but I got it to the point where there were several high spots at the same time, but overall the amount of light leakage was fairly even all the way around. And I'd rather err on the side of caution by having it slightly larger than to be too small and have to start all over again

I reinstalled it alongside the other carbs. Because I couldn't get it to provide a perfect seal, I simply sync'd the other 3 carbs by themselves. Then turned in the idle screw so the other 3 approximately matched the amount of light leakage as the other. Then snugged up the adjustment screw for that carby. Snapped it open and closed a few times and just made sure it was fairly consistent across the board

The Short Version:

File, file, file, check, file, file, check, file, keep checking, file, file, file, stuff it up and start again
File, file, file, file, file, check, file, file, check, file, check ........... reinstall

IT BLOODY WORKS! It started with a bit of choke, then I just turned the idle screw in a bit and holy crap it runs perfect! better than it ever has. Idle is extremely smooth and consistent. Can shut the motor off, walk away, come back and simply hit the starter button. Zero throttle input needed. Revs up and down quickly and consistently
Next step is to reassemble it and take it for a ride, but either way i'm stoked. If I do find an issue it'll only need very fine adjustment

The Bottom Line: Do NOT damage those bloody things in the first place! At the very most these things need to be within a few hundredths of a millimeter all the way around. It's an extremely time consuming and fiddly process
I did this with nothing but hand files, 1200 grit sandpaper to remove any burrs and vernier calipers that measure in 100th's of a millimeter. So it is possible to do but NOT easy

 

Full credit to you, most impressive job and to top it off...........she goes

 

So after the last post I had coolant leaks and an electrical problem. Still chasing the electrical problem but I did fix the coolant leak. After all the spark plugs dried up and stopped shorting spark, I took it for a ride. I've currently got it idling at around 1200rpm, this is low but it doesn't stall out at all so I can tick the 'does it idle?' box. I can hear the revs fluctuate by around 100rpm cycling up and down every second or 2. On decel at 0% throttle its very, very slightly off, with 1 cylinder wanting to fire just a tiny bit more than the rest. Though unless I was specifically listening for it I wouldn't know
At very small throttle opening, up to about 5% I can feel and hear it's uneven, it sounds like its running on 3.5 cylinders (if that makes any sense) but for a homemade butterfly valve thats fine. And is currently the reason why I have the idle at 1200rpm and not 1600rpm. Since on decel it's a bit uneven for the moment. Otherwise its extremely smooth through the revs now, infact I actually preferred it before as there was a noticeable increase in power at 10,000rpm which made it more fun. Now its pretty linear from 1000-18500rpm, though does feel like it runs stronger overall

Bottom line is its running pretty damn well for a homemade butterfly valve. And this is without even touching the adjustment screw for that carburetor, so it may simply be a matter of fiddling with that. In the meantime i've ordered some new spark plug wire, caps and seperators, as #3 shocks me when I wiggling the wire. After I make sure the leads and caps are 100% i'll make another butterfly and keep this one as a fall-back, as I know its good enough to run permanently if I have to