Fork springs, preload, and sag

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bushx
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Fork springs, preload, and sag

Post by bushx »

As a long time owner of another vintage motorcycle, and member of it's email listserve since before the internet, I get how repetitive newb's questions can be, so please bear with me, lol.

1, is there a way to identify the springs I have in my forks, they have the number 341623 marked on them.

2, I started by measuring my sag. Got 12mm static, and about 50-60mm race. Not enough.

3, measured preload spacers, they're 90 mm resulting in about 26mm of preload on the spring. If i've read correctly, current line of thinking is 5-10mm is a better number for plush forks.

I'm thinking I set it at 10, and recheck my sag numbers. I'd like to identify what springs are in there tho.

PS, i'm about 200lbs without gear, and ride in a rocky rooty area, 1st rid out, the forks were way too stiff/harsh in the initial travel. Going to get the springs and sag right, then play with compression clickers.

Thanks.
scriberman
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Re: Fork springs, preload, and sag

Post by scriberman »

Not sure abut the numbers but try this, http://www.reliablespring.co.uk/calculator.htm
Silverfox
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Fork springs, preload, and sag

Post by Silverfox »

Get springs and do the Shim Stack Mod, huge improvement!
KarlP
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Re: Fork springs, preload, and sag

Post by KarlP »

If you have the 90 mm spacers you most likely have the OEM springs which are too light for a 200 lb guy.

A nice improvement is to use XR400 springs. There is a .40 and a .42 OEM offered. It seems the OEM springs are preferred.

The XR springs are longer so you make your own preload spacers

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KDXGarage
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Re: Fork springs, preload, and sag

Post by KDXGarage »

1996 - 1997 Honda XR400R is .38
1998 - 2004 Honda XR400R is .40

You need stiffer than .40.

You can get the springs rate checked at a suspension shop or just go ahead and buy the correct ones. With a number on them, they don't sound stock. Race Tech is now suggesting 4mm on preload.
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bushx
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Fork springs, preload, and sag

Post by bushx »

I'm pretty sure the front springs are not stock. I've trimmed my preload spacers to give ~7mm of preload, and I'm still only getting 2.5" of race/rider sag. Free sag is about 1". If what I read is true, leads me to believe the springs are too stiff if anything. That said, I'm going to ride it this weekend. I'm confident that it will be an improvement. I'm not racing, just trail riding at a healthy pace (ie. a pace that keeps me healthy, lol). I think the rear spring is stock, at least it looks like it from the colour (light blue?). I've got the rider sag dialed in and the static sag is at the upper end of good @ ~35mm. I didn't have any issues with the rear bottoming last ride. Going to play with compression and rebound a little next weekend, but I think I'll be able to dial it in enough to be happy with it. Thanks all.
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