What XS650(?) Or Yamaha Forks Are These ?

Fred Average

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I’m simply trying to find out and the prior owner didn’t build the bike or know,they don’t look like they were the original forks to an 1975 XS650B pictured here.
I can get more detailed pictures to anyone that can help , so I can get the correct new seals ,bearings ,wheel bearings seals etc. Thank you for the help
 

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Looks like early stock forks to me, swapped left to right, to get the caliper behind the fork slider. Should be 34 mm fork tubes.
BTW, I like those early calipers a lot better than the 77 and newer calipers.
 
:agree:
mebby a warp 9 rim on the stock wheel hub, looks like a stock brake rotor, drilled.
 
Yes, normally, the axle inserts from the left and the axle nut is on the right. Yours is the opposite. The main issue with doing this is you lose a functioning speedo drive. Normally it mounts on the left but now must be moved to the right side. It can only be used there as a spacer because it's drive part is now spinning backwards, lol.
 
Thank you all,any more input would be appreciated😊👍
Can anyone suggest the best place ,hood reliable source to purchase OEM fork,wheel bearing seals,damper rod bolt crush/sealing rings,riser bushings for the handlebar mounts etc?
Mainly I would like to know if that’s the original front end for the bike or at the least a XS650.
I have a perfect fully rebuild SR500 fork & leg tube assemblies,but the caliper castings/ears are in a different location. Thanks again all.
 
SR500 forks have 35mm tubes and are actually very similar to the later 650 forks. But, your current forks have 34mm tubes so the 500 ones won't swap, unless you changed to a later triple tree. But you would need more than that, you'd need a later style disc and a later type caliper too. You've noticed the difference in caliper mounts. There's also a difference in disc offset between your early disc and the later style.
 
Mr. 5twins , thank you so much,yeah I was wondering about that because we used to take a lot of the wheels,brakes ,hubs off XS650’s for TT500 dirt trackers and SR variants.
I was wondering if that 34 mm I saw was a typo on this site, as you probably know your Yamaha parts interchangeable.
And that’s funny that they went down 1 mm from the 500 forks to the 650’s Basically all I want to do is a service that front end , get Ferodo pads and keep riding it as it’s not a race bike anymore.
So does it look like a stock XS650 caliPER to you? And if so what year?
Lastly, Any thoughts on a good OEM parts supply house for replacement parts or decent quality supply source?
Thanks again for all your knowledge and input.
“Fred”
 

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The 650 34mm forks were before the SR's time, used up to '76. In '77, the 650 got 35mm forks very similar to the SR forks, as I mentioned earlier. The '77 and later 650s also got a new caliper, a "mirror image" of the SR one, mounted on the right side .....

NewWheelMounted6.jpg


You appear to have an early 650 caliper. It was used from '72 to '76. They were all the same as far as I know so I guess yours could be any one of those years. That early caliper could be fitted to either side by changing around it's mounting bolts.

I see you did the spoke wheel conversion on the SR. I always wanted to do that to mine but, alas, it's too late as I sold it last year, lol.
 
The 34 mm forks may be slightly inferior (i.e more flexible) to the 35 mm forks, but since a street tracker should be quite a bit lighter, they should at least be on par with a stock XS with 35 mm forks. Comparing stiffness vs bike weight (mass).
The early caliper has 2 x 48 mm pistons, where the later caliper has 1 much smaller piston (38 mm?)
That is a signinificant difference. I also fine the early 2 piece disc much nicer. No doubt the later type disc was some kind of cost saving exercise. Altogether, I think your front end is the better of the two.
On my 74 RD350, which has the exact same caliper, I use a 13 mm Brembo master cylinder. Even with the smaller 267 mm RD disc, that front brake is just as good as some current bikes. A genuine 2 finger brake.
 
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