Fork I.D. needed, non-XS...... ID FOUND, THANKS

[DogBunny]

This has me really stumped. I suspect it is non-Yamaha. tubes are 35mm, LONG, and enduro-style. Axle is 15mm (smaller than XS650). Fitted to an XS650 frame.

Left side has multiple mounting eyes. Right side has a single locator. Right leg says "ALCOA".

Has horn mount holes, so must be from a street-legal bike (red arrows). Fender mounts to bottom triple (green arrows).

Has mounts for speedo/tach/dash and for ignition switch.

Thank you!

 

[DogBunny]

solo, good eye, except... Yes, I actually went to the trouble of removing the fork bolt under the black cap -- it's exactly the same as the fork bolt on some years XT500 and TT500. So, I looked up the part number, saw what other models it fits, checked them all out, and got nothing. I just tried the same thing with the SR500 fork bolt, (and black cap) still nothing.
This leads me to believe that my fork is non-Yamaha. I think the same fork bolt must be used on a different make, with a different part number used by that brand.
However, it could be Yamaha. The horn mount holes are exactly like an XT500.

 

[DogBunny]

Yes! Wow, excellent. I'll never know how in the world you found that. I did a little part number cross referencing, and the 1990 RT180 front end is also the same as the 1991-1993 RT180 front end, except they have black-painted top steering crowns. I also cross referenced the RT180 top fork bolt and cap -- they have part numbers only shared by the 1990-1993 RT180, so they re-numbered the old XT/TT/SR500 parts.
Honestly, I spent a lot of time searching, and was about to go down a Honda models rabbit hole. Thank you! I owe you one.

 

[jddenham]

Coming in years later here...I picked up a project bike with these same forks fitted to the frame. Did you end up using them on your build? Im curious if the calipers and rotors of the RT180 are "safe" to use for the weight of the xs650.

 

[DogBunny]

No, I did not use them. They are long gone. I probably sold them on eBay.
BTW, I am in Austin, and I have tons of XS650 parts. I have a good set of XS650 forks if you are interested.

 

[jddenham]

That's great that you are in ATX, I have another frame with the original forks, so I'm covered there; though there are several other parts I will be needing like a left crank case cover for a '79 or '80 xs650. I'm going to be pulling apart the engine and seeing what service needs to be done. After that it'd be great to link up and see what all you have.

 

[DogBunny]

Sounds good. I'll PM you.