Hi Guys,
I am in the process of doing the modification myself. Here is what I have found out so far. I am going to use a front end from a 2006 Honda CRF250X. Nice as it has a speedo connection. tyre size is the same as my stock AT wheel.
From what I have found so far is that you will need a spring rate of between 0.58 to 0.65N/mm. (This is dependant I think on your weight as well) Not sure which forks you have but the standard spring rate for mine is 0.42. The highest spring available for my bike is 0.52. You can go to
www.racetech.com, then click on spring rate search, then select your bike and model, then click on calculate spring rates and display available springs.
At least then you know what is the highest available.
So we sit with forks that we can't use, or so I thought. After searching and speaking to alot of suspension guys. A lot of them said, they were not interrested in doing the conversion, but I found a few that are willing. Aparently if you cut the spring, it increases the rate, and then a spacer is put into place to make up for the cut out part. This aparently involves some mathematical calculations. So mine will be going to a suspension guy here in South Africa soon for the conversion.
The next obstacle is that the forks are alot higher than standard. Aparently, even with the KTM 990/950 WP forks, this is an issue. One guy told me they do alot of KTM conversions on the AT, and they shorten the forks. I am not sure how this works, but I think there is no cutting, it is a matter of spacers etc, or this is so far what I have been told. I still need to research this a bit more. dont want the front to be exxessively higher.
Then the tripple clamps. Your steering stem needs to go to a engineering works along with your standard one, so the can do their magic.
The last thing would be the 320mm brake disk conversion, which is pretty easy and can be found on e-bay. Although here in South Africa, NO ONE supplies this, so I will have to import it.
I hope this helps a bit, and if anyone can correct me if I am stating anything incorrect, please do so, I am only giving the information I have been given so far. I hope to start my conversion soon.
Every time I get into the garage and have to look at my new front end and see that its not on my bike I get very demotivated by the amount of work that needs to be done to get it on.