Suspension setup for a fat guy

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Suspension setup for a fat guy

Postby BigRed8019 » 09:48 am Jun 13 2018

Hi all. I have a 2001 220r that I am needing to respring for my weight. I have entered in my info (Trail, 45 years and older, Novice, Standard Height, Standard Gas Tank and 300 lbs without gear) into Racetech's calculator on their website and it is giving me .449 for the front and 6.29 for the rear. I contacted Jeff Fredette and he recommends .44kg springs for the front and the 5.4 kg on the rear.

It seems that both agree on the front spring rate but they are far off on the rear spring. I bought a new 6.4 rear spring and haven't installed it yet but I am really confused by the discrepancy between the two. I am more inclined to believe Jeff but not sure based on searches I have done on this site with recommendations of a 5.4 spring for riders who weigh a lot less than I do. Any help?
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Re: Suspension setup for a fat guy

Postby Jason » 10:49 am Jun 13 2018

Short version: 0.52 and 6.2

Long version:

I do not agree with either suggestion.

Put on all your riding gear, water backpack, contents of tool bag or any spare parts (anything that makes the weight greater than the stock bike). At least 315, correct?

0.48 Kg / mm rate springs are as stiff as Race Tech makes. Beyond that, Cannon Racecraft makes custom springs. I say get the 48's. I raced MX a couple of years ago at 240 pounds in gear and ran 48's in my KX250. I had 44's to start (stock, too soft), then 46's (better, but not stiff enough), then the 48's. Your weight is about 0.6 stiffer than me. MX is about 0.02 stiffer than off-road in my experience.

The main job of the springs is to hold up the combined weight of the rider and bike. As the combined weight goes up, the spring rates need to go up to get the same sag numbers.

Also, in my experience, we are all in one of the following three categories...

One: Do nothing and just ride, being ignorant of how much better it could be
Two: Buy one set of forks springs and one set of shock springs, then say "WOW! This is so much better. I am happy with it now"
Three: Goldilocks, buy a bunch of springs and test them all out and have one set that is too soft, one set too stiff and one just right.

Please be aware that making huge rate changes will mean at least adjusting the clickers to compensate for rebound. No clickers on the front, so it will be a bit more lively.

I'd rather have the stiff springs and a little bit of concern on rebound damping than the stock springs.

The stock fork springs are way too soft in stock form for almost everyone. They are 0.35. 1989 - 1994 is 0.30, just to show you how different current spring rate and damping theory has changed.

On a 1995+ KDX, 5.4 is roughly for someone around 225 all geared up. Stock is 5.0 and good for around 175. Tack on 25 pounds and 0.2 rate as the scale goes up. ROUGHLY!!

As always, check your sag numbers!
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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