VTR1000F Choke Nut

EDIT: The first version I uploaded should work with a bit of filing or sanding. The issue is that the thread engaged into the carburetor is too long. The base of the thread sets the most retracted position of the choke needle. Mine pushes the needle in 3mm too far. Maybe not a problem but I've adjusted the file to have a shorter thread. 

If you've done any carburetor work on your VTR1000F Superhawk / Fire Storm motorcycle the chances of you breaking the plastic choke nuts is very high. Replacement parts are available but only in a kit that costs north of $100. This part is easily made on a resin printer and fits like a dream. 

I've made a couple of modifications to the part to help in durability and assembly. The threaded section is 7.75 mm long instead of 4.5 mm long.  The depth of the plunger is compensated for so the spring preload is the same. The ring stop is slightly greater in diameter. 

There is another choke nut out there that someone has made but the threads were very short and not well formed. I had to tap them to make the part fit and then I didn't have any real confidence that the part would stay in place. It took some doing but I was able to render an ISO thread that prints nicely. It supposedly has 6e tolerance but the final value will depend on your printer. Running an M10 1.25 bottom tap into the carburetor to clean up the threads is a good idea if you have corrosion or have damaged them extracting the broken part of the old choke nut. A few minutes in a vinegar bath should work too.

You absolutely should pretest your nut fit in your carburetor. If for whatever the reason, your carburetors don't allow you to fully thread in the choke nut as I have designed it, take a file or belt sander or whatever and remove some of the thread to allow full seating on the ring boss. You need this feature for the stability of the part when installed. The spring pocket is indexed to this ring boss so you won't be affecting function of the part. 

Recommended resin is anything that has good strength and toughness. I am not too worried about temperature resistance because even though this area of the bike gets warm, the carburetor is cooled by the latent heat of evaporation from the fuel and has cool air shooting through it all the time. 

Good luck and keep these cool bikes on the road!

I do not know what other models this part may fit on. I imagine that many older motorcycles have similar choke arrangements on them. Let me know what you discover.