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USD forks on XJ900RN

Discussion in 'XJ Modifications' started by Core, Apr 17, 2017.

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  1. Core

    Core Active Member

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    Hi Forum,
    Wanting to hear from someone who could shine some light on the swap out of the stock front end to some later model (2000´s) USD (up side down) front end.
    The build is a cafe racer / brat look. The bikes existing front end is missing parts so an outlay is already necessary, so I thought instead of investing in that direaction, go directly to modern front end with the meaty USD fork look.

    Have heard of some conversions that are literally bolt on and some that need some mods.

    Anyone done this and can share their valuable wisdom?
    Thanks
     
    Core, Apr 17, 2017
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  2. Simmy

    Simmy Well-Known Member

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    If you go with a complete front end including the wheel you might have problems mating a rear tire.
    Typical 17" front rims are 3.5" . I think your rear is around 2.75 (2.5?) and the shaft drive/disc brake limits your options.
    I've never ridden a bike with a wider front rim than rear.
    I suppose you could put a skinny rim upfront but that creates even more work.
     
    Simmy, Apr 17, 2017
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  3. Core

    Core Active Member

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    I see your point. Did not think of this.
    I had noticed that my wheels are 18" while during casual searches for tyres the choice for 18" tyres seems to be quite limited.
    I do not know the width of the rims on the XJ900RL
     
    Core, Apr 17, 2017
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  4. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    You can fit a narrower wheel to any fork so long as the axle size is the same. You'll just need to make, or have made, spacers to keep the wheel centered in the fork.
     
    k-moe, Apr 17, 2017
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  5. Simmy

    Simmy Well-Known Member

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    The OEM's were all over the map sizing sportbike rubber in the 80's. 19 and 18" fronts were the norm, then in 83 Honda and Suzuki brought in the 16" fronts, 17 & 18 rears. This was the fad, Suzuki's 1st gen GSXR (1985) had 18's front and back and radial tires.
    By 88 everyone settled on 17" radials and they've been there ever since. The racing world dabbled in 16.5" but this never made it to the street.
     
    Simmy, Apr 17, 2017
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  6. Simmy

    Simmy Well-Known Member

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    and then deal with the brakes.
     
    Simmy, Apr 17, 2017
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  7. Core

    Core Active Member

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    Thanks for the background Simmy.
    That puts things into context for me quite well.

    I had the idea to convert this X900RN to a brat/cafe style
    Part of the change was going to be a meatier looking front. What seemed to be the logical way forward on that account would have been a more modern USD front end.
    Wider front and rear tyres. Probably the same size on both.
    Hmmm. Now I see that this may be harder to achieve than I expected.

    I don´t want to mess with milling out special triple trees, or getting spacers just right with disc calipers (good point Simmy).
    Id change the whole front end or stay with the stock and do some smaller mods.

    Thanks guys for your deep wisdom
     
    Core, Apr 17, 2017
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