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1990 YZ250 Triple clamps


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Does ANYONE own a 1990?

I'm beginning to think they're rare...

I'm working on a project bike using the front end off a 1990 YZ250 but I don't have the triples. I bought a set from a 1990 KX250 because the bearing sizes were identical to my project frame so I thought it would be a perfect swap... The problem is the KX spaces the fork legs farther apart than the YZ does. This is obvious when I bolt the wheel/spacers/axle/forks together and the width is narrower than the KX triple clamp bores. I need to know what is the "pitch" or distance between the fork legs on a 1990 YZ250. Can someone please measure theirs and let me know? If possible, in millimeters and it doesn't need to be from the center of the bores, just the distance between the fork tubes would be perfect. I can figure out the rest from there. Thanks for your help! Y'all are my last resource.

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You're awesome.

Yes, I need the distance between the 2 fork legs. I am only using the lower fork sliders for an all-rigid boardtrack styled bike project. These lower fork legs are being held by regular ol dirtbike triple clamps because I figured out the rake and trail numbers I want using these clamps, leading axle fork, wheel size, etc. What I failed to take into consideration was the fork pitch. Apparently, Kawasaki spaced their forks apart more than Yamaha did in 1990. So, I need the measurement Yamaha used. I can possibly machine new spacers to make up the difference, but more than likely I'll need to find a set of triples for a '90 YZ250 and fab up a new steerer tube to the length I need. I don't know if the YZ125 used the same spacing, but the upper and lower triples on the 125 are a different part number... 👍 I believe the upper triple clamp fork bore on the 1990 YZ250 is 51mm and the lower triple clamp bore is 56mm. If you find this to be true on your bike, then I just need the distance between the bores. I can figure out the rest. That may be a more accurate measurement than finding the center of the fork tube bores.

Thanks again! I REALLY appreciate it!

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going from the inside to inside of the fork tubes at the lower clamps looks to me to be about 129mm. other specs I got are 41mm for the fork tube diameter, and 27.5 degree front end pitch. Do you know what the "trail" of the front end is? In my manual it says the trail is 122mm, whatever that means. hope all that helps

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Here's another question, what are the steering bearing sizes on the 1990 YZ250? Everyone has kits, but no one lists the actual bearing sizes. Is there a chart somewhere or does anyone know off hand? I know they're different upper to lower... I think the steering bearings are common between 1988 to 1995? Does that sound right?

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