Mikuni Carb Throttle Shaft Butterfly Screw Removal Aide

So, I finally got to experience the joy of trying to remove the throttle shaft screws on the Mikuni BS35s for my '83 XJ900. Fortunately, I have some junker BS35's and I was able to practice on one of those and realized it's a really dangerous job. One slip of the grinder and its good-bye carburetor (yes, I know first-hand from practice).

I thought "if only there was some way to protect the carb, the job would be a lot less risky."

Then I remembered I have a 3D printer. I jumped in Fusion 360 and started whipping something up. The first prototype was a guard that screwed on to the end of my Ryobi rotary tool to cover most of the grinding wheel. While that seemed like it might work, it was kind of awkward and hard to see what you were doing, plus somewhat specific to my tool.

The next iteration took a different approach, and I made something that fits in the carb itself. Took a few tries to get it right, but in the end it worked fantastic!

I uploaded the model to Thingiverse. You can find it here:
https://www.thingiverse.com/thing:6836104

Here's a video of the insertion process:


Installed with backlight. Just need a small diameter grinding bit and you're set to go.


The guard after its first use. Caught quite a bit of the dust, though not all.


The screws after grinding:


Hopefully this will help somebody else out too. The model could easily be adapted to other size carbs as well.

 

Excellent idea!