Fork Tube Swap

[hjennings]

If I recall correctly the XS400 has 33mm tubes, yes?

I've done some searches on the forum and all I'm finding is swapping triple trees or converting to inverted forks. I don't want inverted forks, just beefier forks with a larger diameter.

I'm thinking boring my factory triple tree out and swapping in larger tubes and lower forks. I'm thinking something in the 40mm range, depending on what is out there on the used bike market for a reasonable price. Only real requirement is I want dual disc brake mounts. I'm sure I'll have to do some swapping of bearings to get the front wheel to fit correctly (18" mag).

Has anyone does this? If so, what tubes did you use?

 

[bcware]

The triple tree (yoke) is aluminum on top; I'm not sure it could handle being bored out. I'd be real hesitant to even do it to the bottom yoke. Way too risky in my opinion.

Why do you want larger forks? Just for looks? Are the double discs just for looks too? Just trying to figure out what your motives are.

I am pretty sure I have heard of it being possible to get a fork lower from a different yamaha bike making it possible to mount double discs to the stock uppers.

 

[hjennings]

Yes for looks. Getting lower fork tubes for the dual disc setup isn't a problem. Some of the stock lower tubes have this setup. Larger diameter tubes would just help with the look I'm going after.

Just browsing on eBay and there are a lot of options for 39mm tubes and forks. If I'm correct with the stock XS400 tubes being 33mm that'd be just under 1/8" out of the triple tree hole.

 

[BamaBill]

You would compromise the strength too much of the triple tree by boring it. You would be a lot better off hacking the neck of the bike and welding on another neck from a bigger bike with the frontend your looking for.

 

[hjennings]

I think I'd just swap triple trees with corresponding bearings before cutting the front of the bike off.

 

[BamaBill]

Have you looked at what size an xs400 Maxim tubes are? I know they are bigger, and just rough measuring I think you could match the bearings up to make the Maxim triple tree work. I actually have a Maxim tree sitting in my shop that I purchased by accident when rebuilding my bike.

 

[BamaBill]

I think then you would have to deal with matching a front wheel with the same axle diameter to do your dual disk. I think the Seca may have the same tube size as the Maxim and dual rotors. Just an idea, but I could be wrong.

 

[hjennings]

I haven't looked up the Maxim yet, but it should be here on this list somewhere. http://organ-donor.org/motorcycle-data/fork-tube-diameter-list/

Swapping on a different triple tree with larger tubes and then matching my stock mag wheel to the new forks is do-able.... It's just where to start. I was hoping somebody had done something similar to this and had some ideas on what works and what doesn't.

 

[hjennings]

Does anyone have the bearing specs for the XS400 neck and the axle size? I could use that data then look up various bikes from say the list of 41mm bikes and go from there. That list is only Japanese bikes. I know there are a lot of Harley bikes that size, too. It's just what I can find that'll work (by swapping bearings, etc) and what is out there for a decent price.

 

[Builtin_DaShed]

Here's some other links for info. (sure others know about these?)
http://www.customfighters.com/forums/showthread.php?t=29199
http://www.clubchopper.com/forums/m...ube-sizes-neck-bearings-axle-diameters-2.html

from the lists for my 81 xs4, not actually verifyed with physical measurements
33mm fork tubes
steering neck bearings.
upper - 25x48x13
lower - 30x48x13
inner, outer, height
Front axle diameter- 15mm
rear axle diameter- 17mm

Here's a couple links for good info on Harley narrow glide forks
http://www.jockeyjournal.com/forum/showthread.php?t=98402
http://xlforum.net/vbportal/forums/showthread.php?t=715412