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CB rat / cafe

98K views 415 replies 106 participants last post by  rabies  
Looks like the bearing sizes are

top
35 x 55 x 14

bottom
35 x 55 x 14

My opinion is to have the 636 stem turned down so that you can use a 30 x 55 x 17 bottom and a 25 x 47 x 15 top. or press your original stem in to the 636 triple.
 
Its possible to change the lower race and use the 636 bearing, but the top is going to require machining. Is the stem hollow? If it is then I would have the top turned to to 30mm and use a 30 x 47 x 15 conversion bearing.
 
I did a little research for you and this is what I have come up with. The best solution for you is to swap the stem from the cb into the 636 triple its going to require some welding/machine work but you will be able to use stock bearings. This is the other option: is requires a 35 x 55 x 14 tapered roller bearing, you will need to press the stem out and have the upper bearing surface turned down to 30 mm, then you can use a 30 x 47 x 15 conversion bearing available here http://www.twfracing.com/images/zparts/steering_head_bearing_lg.jpeg