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Thread: 20 -> 25mm axle conversion

  1. #1
    Board Newbie Danimal's Avatar
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    20 -> 25mm axle conversion

    First post, and hopefully many more to follow. I have a question about changing axle sizes on a KX 250. I am currently in the middle of a supermoto conversion and I am going to make it street legal. In the process of doing this I found some SM wheels that were just too good of a deal to pass up, and they are Kawasaki hubs that are the correct width, but they are for a 2003 when they changed the rear axle to 25mm. I am trying to decide if I should do one of the following:

    1) Shave my swing arm (2.5mm) around the axle channel and buy a 25mm rear axle

    2) Try to locate the all elusive sleeve needed to fit the stock axle to the bearing size.

    3) Find a place that has bearings that fit the old axle and the new rims.

    Any advice is appreciated and links to places that have the products that I am looking for would be awesome. I have been looking all over for the last couple days and these were common solutions to the problem, but I am not finding a place that sells the correct bearings, or sleeves for this application. Also I am not crazy about shaving my swing arm, although I have been reassured buy a mechanic at the local bike shop that it would not structurally affect the bike if done properly.

  2. #2
    Member Penadam's Avatar
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    Re: 20 -> 25mm axle conversion

    Have you considered going to a machine shop and having a sleeve manufactured? Or try grainger and see if they have the size bearing you need.

  3. #3
    Board Newbie Danimal's Avatar
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    Re: 20 -> 25mm axle conversion

    I have looked into both options, and I think that buying the 25mm axle and spacers is the best way to go. Even though I am shaving some of the aluminum off, It is supposed to actually be a more rigid system due to the larger stronger axle tying it together. Also my current axle is not in the best shape due to me riding the bike in the sand dunes a lot when I first got it. It probably needs to be replaced and it costs the same as the 25mm.

    Granger is a source that I had not thought of before though, so I will look into that before I fire up the die grinder.

  4. #4
    Senior Member TFOGGuys's Avatar
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    Re: 20 -> 25mm axle conversion

    Conversion bearings are probably about 8 bucks a piece. The spacer between them is nothing more complicated than a piece of thickwall tubing. Rather than modify the swingarm, it makes more sense to do this.
    Thanks, Jim
    TFOG Wheelsports, LLC
    www.tfogracing.com
    303-216-2400

    Calling an illegal alien an "undocumented immigrant" is like calling a drug dealer an "undocumented pharmacist"



  5. #5
    Senior Member brennahm's Avatar
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    Re: 20 -> 25mm axle conversion

    I'm with Jim. Also, if Whisler Bearings off I-70 doesn't have the ones you need I'll kick Zach in the balls.

  6. #6
    Board Newbie Danimal's Avatar
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    Re: 20 -> 25mm axle conversion

    I looked into the bearings as an option, but my problem then was that when they switched to 25mm axles they also switched to a 240mm rear disc brake with a 4 bolt mount from a 220mm 6 bolt and no one ever made a 220mm disc on a 4 bolt pattern with that spacing. So I won a auction on ebay and got a whole rear brake assembly with pads, master cylinder, hose, and lever for $45 and it is for a 25mm axle and 240 mm disc. Then being that I needed to replace my old axle anyway, the only additional expense was the axle spacers.

    I found a couple places that make custom axles and custom rotors, but the expense of that was way more than just doing a complete conversion to a stock setup for a newer bike. It probably would have been about the same price to just buy the correct wheels new in the first place, but where is the fun in that?

  7. #7
    Board Newbie Danimal's Avatar
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    Re: 20 -> 25mm axle conversion

    Man I am a little bummed out. I just got my bike all back together and started it up today. It started on the second kick after a full engine rebuild. I warmed it up and was looking for problems and found a small coolant leak. I stopped the bike to fix it. Then when I went to fire it back up the kick start fell off. I thought that I was an idiot and forgot to bolt it on, but it turns out that the kick start shaft sheared off. So now I am waiting on more parts. Hopefully the rest of today is a little better.


  8. #8
    Senior Member AOK303's Avatar
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    Re: 20 -> 25mm axle conversion

    damn that must of been one hell of a kick start
    No tickets YET this year *Knock on wood*

    07 Audi S4 DTM
    06 CBR 1000rr

  9. #9
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    Re: 20 -> 25mm axle conversion

    Quote Originally Posted by AOK303 View Post
    damn that must of been one hell of a kick start
    Yeah let me tell you what. It looks like it had been cracked for some time and just gave out at the worst time. I just had the motor out and did a full top end and main bearings and seals on the bottom. So it looks like I am opening it up again next week when the parts come in. I had the bike up on the platform stand when I was starthing it too. I almost went over on my face with the bike following me.

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