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Mixing fork spring rates on XR400R

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About 2 years ago I got my 1997 XR400R, a very nice machine indeed. Problem was the suspension, not at all suitable for me.

I went ahead and found my spring rate in the racetech site, but the stiffest spring I could get was 47. I decided then to try a cheaper option for shipping overseas, because I live in Thailand and shipping is sometimes as expensive as the springs themselves. 

 

I found 47kg Eibach springs on ebay for a good price including shipping. When I changed the fork springs I was very happy with the outcome, when I rode with other people I found out I was still too soft on the front. 

 

I placed another order with Cannon Racecraft, they recommended 64 kg custom weight springs for my rider weight of 138 kg. When I changed the springs I was firstly in heaven, no more fork flex or washing out in corners, when I got into the more technical staff I got stuck and couldn't keep up with the rest, obviously this time I was to stiff on the front. The rear seemed okay with the 13.6kg shock spring from Cannon Racecraft. For many month I talked myself into believing I have lost the ability to ride until I came to the conclusion I might want to try out mixing the two different fork spring rates. After a little research I saw it was done before, but the gap between 47 and 64 kg seemed to be a little big. Nevertheless I went ahead and did the swap on fork. Took one 64kg spring out and replaced it with one 47kg spring.

 

I was very excited when I went on the first ride, but boy was I happy. I had to take it easy because was still running in the engine after a rebuilt. Very soon it became clear that this setting was the best so far, much better then anything else, even the technical staff went pretty easy with this setting. I've been riding this combination now for a couple of weeks and I am still very happy with this set-up. 

 

It would be nice too hear from you guys here, what's your opinion about this or if there are any disadvantages that I am unaware of.

 

Love this forum has great and very unique informations in every field, much appreciated.....thank you so much!

 

 

here's my youtube channel for some cool videos from Thailand:

https://www.youtube.com/channel/UCfe5DFBd6Dugo84X1cUDhQQ

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I don't see a problem running different spring rates per side. It's pretty common. The oil viscosity and oil height in the forks will make a difference too. The trick is to get the valving (your compression and rebound clicker adjustments) of each side to work well together.

 

Cool trail videos.

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I don't see a problem running different spring rates per side. It's pretty common. The oil viscosity and oil height in the forks will make a difference too. The trick is to get the valving (your compression and rebound clicker adjustments) of each side to work well together.

 

Cool trail videos.

 

Thanks trailryder42 for your response, I was thinking the same but, I am not an expert and it's always good to hear someone else's opinions. Cheers

I just wonder if I was to put the original 42kg spring and the 64kg together but the gap might be too big.

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I just wonder if I was to put the original 42kg spring and the 64kg together but the gap might be too big.

 

That's why I said the trick is to balance them out with your valving, oil viscosity and clicker settings. I wouldn't think you'd want to set each fork tube the same.

 

Example: On the heavier rate side, I would think you'd want very little, if any, compression damping. Seems to me like you'd want to control compression damping with the lighter side and rebound with the heavier side. Make sense? Don't be afraid to experiment.

Edited by Trailryder42

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Bruce Triplett's awesome "Terrain Tamer" forks have segregated damping.  One fork is Compression-only and one fork is rebound-only.  The compression adjuster on the rebound-only fork becomes a rebound adjuster.

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