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1985 RTL 250s Headstock Replacement Bearing Assembly


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I found a person modifying taper bearing for use in the RS125R. That bike only uses it in the top.

He gave me a measurement to check on my RTL head stock. If I have the clearance his part should work. It may take a week to get back to this, but once I know something one way or the other I'll update this post.

If anyone else should have useful input on this subject please respond. Thank you.

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  • 6 months later...

Hello all,

I've just joined as I have the same Bearing issue. I am changing the forks (as I don't have the top clamp and stem) to USD Derbi forks. The method I am employing is this;

Measure stem width. Mine is 25 mm at bottom and top. (RS 125 stem is NOT 25mm top and bottom but it is same as 

Measure Honda RS 125 NF4 steering tube, this is 55 mm bottom and 47 mm top

the old ball races depth is 12 mm at bottom and 8 mm top.

The problem is Honda doesn't make/supply these parts for RTL or RS respectively



What i'm in the process of doing is first find bearing to suit stem then to suit outside diameter.


gives some alternative bearings for my 25 mm stem with/without seals. NOTICE these are ball bearings for the bottom and is 12 mm thick.

https://www.ebay.co.uk/i/321858810549?chn=ps    15mm thick 

this gives a ball bearing for the top.

these bearings are too thick for standard replacement. This issue was discussed by Kiwi Biker


for me im in the process of using taper bearings as they fill in the gap between the Derbi Forks and the Honda steering tube.


To get original ball bearings in it is a case of sourcing the correct size of bearing and get them skimmed/ground down.



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 Hi Ed,

I've had to put this project aside though I did buy modified taper bearings from:

Technical Sports One
9920 Prospect Ave Suite107
Santee, CA 92071-4349
(619) 258-0125
(619) 258-1450 fax

These modified bearings have the frame (steer tube ID) clearance necessary to work in my '85 RTLS. I couldn't speak to other bikes, but Leonard can provide the measurement specs so you can check your specific bike.

One other thing I recent discovered that has seemingly never been discussed in this forum. A Cota 4RT yoke and factory Honda part number bearings fit w/o any issue in the pre-disc brake RTL250S. Yes I'm aware this is an issue for some riders in certain classes. I also can't say this fitment works in the disc brake RTL250S ('88-'90).


Edited by slip_kid
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