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Discussion Starter #1
I'm an old dual sport rider in Oregon, doing mostly back roads. I take my 2002 KTM 520 EXC in the back of my Transit Connect to where the dirt or twisty roads begin, and just bought a set of Excel 17" wheels. The riding is all at legal limits, so 65 mph top end is fine. My goal is to keep the stock KTM front brake disk, and arrive at a sprocket compromise so I can use the same chain without breaking it. I'm running 14/51 for dirt roads, or 13/51 for trails.

I want to do the change in half an hour or less.
1. Replace front wheel.
2. Reprogram Trail Tech Vapor wheel diameter.
3. Replace rear wheel, ideally with 14/47, although I'm not sure I have enough chain adjustment.
4. Replace Trail Tech side stand leg with correct length for the wheels.
5. If necessary, go to 15T front sprocket.
Is this realistic? I'm just hoping to cruise and see the outdoors at moderate speeds with a smoother pavement ride.
 

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In a nutshell....... Nope, not in that time frame.

For one your 2002 front end has only a 22mm front axle.... so you will need the spacer kit because 03 and newer RFS bikes have a 26mm front axle.

Also, a stock front EXC, MXC, SX brake rotor while it may actually bolt onto that front hub of the other wheel, you are going to run into fitment issues with the spokes. that is why there is a larger 310mm or 320 rotor mostly used on Supermoto 17" wheel sets. I also cannot count the times I have seen someone try and use a MX version front brake caliper with a bracket even to use it with a larger rotor and find out that it quickly boils the fluid and becomes spongy, If your going to run the 17" wheels you need a proper front brake caliper/rotor set-up. I would never run it the other way..... that small caliper used like you want has allowed me to see too many crashes that end up getting the rider hurt, and you don't need that.

Now what you may find out, is that the rear 5" wide 17" rear wheel is removed and installed a special way, it can be a pain in the butt and cause you to expel various words, but it can be done once you find out how to do it. The axle is the same size and so is all of the rear brake rotors so no issue there.

Soooooooooo

Here is what I did on my first ride after doing lotsa research.


I bought Behr wheels.... (they are the stock units on the SMR) Since you have an Axial mount front caliper The 04 SMR bike came with a Beringer six piston unit, and a front brake master off a Duke. If you are really gonna do it right the bigger caliper/rotor combo needs a bigger than stock EXC master to make it work. This 6 piston unit is an Axial mount caliper and can be bolted directly onto your forks. So in essence I had to change out the front wheel, and install a totally different front brake master....... it is only a few more bolts but well worth the extra braking power needed when you squeeze the lever.
The rear is just a simple wheel swap......there is a trick and I can PM you the way to get it done.

One other thing you will need to also be aware of is the front rake and the suspension differences...... mainly because of the wheel diameter change. Remember you are taking off a 21" front wheel, and installing a 17" wheel, and taking off a 18/19 rear and a 17" there too.... This changes the rake/trail and caused different steering...... There is a cure for this as well, it is a swap out to adjustable front triples off an SMR so you can adjust back and forth.

This swap is not a 30 minute swap over unless you have professional mechanic capabilities and some specific tools..... I have them all and it takes more time than that to remove and install the correct equipment and make sure it is all adjusted correctly.

And I run 14/45 for everything. I own a 2005 525SMR and run track/street/dirt........ it is a handfull, but fun you cannot find on any other brand.:thumbup:
 

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Discussion Starter #3
Thanks for the input

I really appreciate your input on these safety issues. I'll have to think about things carefully before I make the change.

I have ordered the front axle adapters, and I do have the larger front rotor and offset adapter.

As to the rake and trail problem, by measurement of all wheels, my bike will be 1/2 lower in front with the 17s. I have an extra shock, and my suspension guy, SBD, could shorten the stroke to keep the relationship right.

However, for my low speed riding plan, it might be adequate to get another set of 21/18 wheels and fit Shinko 705s.

I guess I could sell the 17" Excels on this forum if it doesn't work out.
 
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