Vintage Dirt Bike Q & A

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PostPosted: Fri Sep 18, 2009 8:00 pm 
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Joined: Fri Jun 02, 2006 11:12 pm
Posts: 159
Location: Salinas, CA
I am having steerer tube length issues trying to put these 83 model forks on my 79 rm400. Is there a known steerer tube that works with these thicker tripples and longer steering head tube of the 79?
Thanks,
Jon


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PostPosted: Sat Sep 26, 2009 4:04 pm 
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Joined: Sun Nov 30, 2008 12:10 pm
Posts: 1010
Location: Connecticut, USA
Jon,

I have '83 RM250 forks and the DLS front brake setup, but they're to be put on an '82 RM250 so I don't really have the answer to your question (they should drop right in).

Would it be feasible to have a machine shop bore out the '79 triple clamps to 43mm, and then use them with the '83 fork tubes? You could probably find a spare set of '79 clamps on eBay if you wanted to bring it back to stock someday.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric


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PostPosted: Mon Oct 26, 2009 11:11 pm 
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Joined: Fri Jun 02, 2006 11:12 pm
Posts: 159
Location: Salinas, CA
The 1980 steerer tube seems to be the easiest answer. It has the same overlap as the thick 84 tripples, and the proper length for the bike's steering head. Yeah! Easy.


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PostPosted: Sun May 09, 2010 1:36 pm 
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Joined: Sun May 09, 2010 11:32 am
Posts: 9
Location: Rancho Cucamonga, CA
hi, i did this same convierson it can be done but i used a 43mm 82 rm 465 front end, the 79 stem uses loose ball bearings top & bottom where the 83 uses taper roller bearings use an arbor press and a little heat on the 83 bottom triple clamp to press out the stem. the 79-82 rm stems are all the same size and posible the 83 is also. now for the fun part, the 83 bottom triple clamp is thicker than the 79 so you will need to take an 1&1/4 inch hole saw and dill out the bottom side of the bottom 83 triple clamp stem hole 3/8 of an inch deeper. (this lets the stem press deeper into the bottom triple clamp) now press the stem back in and use the 79 bearings top and bottom i also used the 82 front wheel, axle,& brake, the 82 wheel is much stronger. the fender bolt patern is same for 79-83 thanks terry


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