All the "21 inch front wheel" swap/info in one place

I have Honda xl250 21" front wheel, with yz400 forks. Just bought
The bike about 6 months ago, it was rebuild from the ground up in Canada
In 2005. The forks are somewhat tall and they had to dent the gas
Tank so forks wouldn't hit tank when turning. I'll try an put a picture up, this
Is my first post. Bye the way great website, xs John's mods post are the best, kudos
To Travis too
image.jpgimage.jpg
 
Had to turn my monitor upside down to view these pics.:laugh: I used a lot of XSJohn's mods as well. Good stuff. My next build is going to be dirt oriented.:bike:
 
The height of the forks is not what dents tanks. As the forks turn there should be stops to prevent the forks from turning far enough to hit the tank. With the YZ forks the stops on the trees or on the frame don't stop the forks before they hit the tank.
You will have to modify the stops to prevent this, or get more tank dents.
Leo
 
Two more questions (until the next one) : if you run with dual brake rotors, can you/how do you mount the speedo to the left side of the hub, and how do you regulate the speedo for the larger diameter (fewer revolutions per mile) tire? Or is there an internal adjustment on the speedometer? And has anyone laced a front hub to a rear rim so they can have a spoked, disc brake in the rear? Don't you need a spacer for the sprocket? Okay, I'm over my limit. Shouldn't drink and type...
 
Depending on your tire size there won't be enough difference in rpms of the wheel to matter. A 100/90-19 tire is about 26.5 nches tall. A 3.00 21 tire I think is a 100 aspect ratio tire. The height of the tire from bead to tread is 100% the width of the tire. So 3+3+21= 27 inches. As I recall 1/2 difference in tire height makes 1 mph difference in the speedo reading.
Most speedos are off by about 2 mph. You are going 2 mph slower than your speedo reads. The 21 inch tire adds 1 mph. So you start 2 slow add one makes you 1 slow.
Close enough.
It doesn't matter if you have one or two disc on the wheel. The stock speedo drive clears the rotors just fine. It does on my 75 with dual disc. It works on all the dual disc European bikes. Yamaha planned for this and designed it to work.
On using a front hub on the rear, yes been done for years, Omar's sells a kit just for doing that.
Leo
 
Here's how it looks (response to #31) - 64-spoke 21" from Mike's XS
 

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