For the specific size, which I do bet is out there, to get that kind of knowlege the only places I can suggest are the companies that have a lot to do with track racing or suspension setup like penske or stoltech. That really is a good question. I might just do some homework on that.
Okay, the non motorcycle trade term for this tool is the hook spanner wrench. Goes by C spanner, pin spanner wrench.
Thing is these types of tools may just be eccentric to whatever they're made for. Yamaha made the oem twin hook spanners in the tool kit just for their shocks. Nearly all aftermarket options are universal or adjustable types. Best bet may be getting a set of oems. Though I'll say I don't like using them myself. The design could be better.
Last Edit: Jan 20, 2019 8:57:46 GMT -7 by lastwish
Yeah, your bike should have come with 2 spanners. Don't you have them? If you bought the bike used and didn't get them, just buy them. They should be cheap. But like Lastwish said, they don't look very good. I'd also mark the rings with a dot to know when you did a full turn, in order to turn preload back to stock, if needed. Good luck.
Last Edit: Jan 21, 2019 18:20:44 GMT -7 by elptxjc