Do I need this part to ride?

OK I need some help here. I want to ride but got a part that I think I need to replace in my speedo gear drive assembly. Any advice?
I removed the part below because it appears to be damaged and not being retained by the C-clip. Bike rolls fine without this washer but the speedo gear makes a little winding noise.
Nobody seems to know what this part is called or where I can get a new one. Tried to order it but the part I got was not what I thought. I don't even know how to describe it. Take a look. Off an XJ550 Seca.

 

That is a shim that keeps the drive gear in the correct relationship with the worm gear. You can ride without it, but eventually the gears, and the holding clip, will wear to the point that the speedometer drive will fail and possibly cause you some big trouble (if the gears bind, and the drive ears on the wheel doesn't shear, the wheel will lock up).

I don't think that the internal parts are avialble individually, but Chacal may be able to get them.
The speedo drives are quite robust, and are the same unit across all Yamaha models from the Era, so getting an entire used drive unit would be a good option.

 

I got a "junker" if you need one to dismantle.

 

Thanks for the feedback. TIMRtoRIDE do you have the part I'm after?

 

I have a whole unit from a 750
I didn't take it apart, and it's weathered. Most likely the shim inside is OK.

 

Sounds great! Is that somthing we can arrange ? Probably can get that little guy in an envelope huh?

 

Sure - I'm busy this weekend, but I'll get the part Monday.

 

I was able to find it locally cheap. I think I'm good to go. Thanks for your offer TIMEtoRIDE.