Suspension Question - Wrist Twisters
 
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post #1 of 7 Old 05-03-2013, 02:27 PM Thread Starter
Tirone
 
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Suspension Question

I'm a 280Lb rider who keeps bottoming his front forks out, the rear seems pretty good when it's pre-loaded all the way up but not super sure what to do with the front forks other than progressive springs. I've read on here about changing the oil weights/amount of oil but I'm not sure if there's a calculator somewhere or if it's just kind of done by trial by error. Any assistance would be appreciated

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post #2 of 7 Old 05-03-2013, 02:28 PM
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You need heavier weighted springs, not necessarily progressive ones, either.

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post #3 of 7 Old 05-03-2013, 02:31 PM
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Hello Fatmouse, do you have a 919? At 280lbs, I believe 1.1kg springs would work. Not sure if you'll get what you want from just changing oil weight/amount but someone who's more suspension savvy can chime in here.

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post #4 of 7 Old 05-03-2013, 02:33 PM Thread Starter
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Oh man, I totally forgot to say I ride a 2003 919. Yeah.

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post #5 of 7 Old 05-03-2013, 02:51 PM
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New front springs for sure. You might actually be fine with the rear shock.

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post #6 of 7 Old 05-03-2013, 05:34 PM
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Don't change the oil weight ! The hydraulics are set up for a certain viscosity, besides, hydraulics are not your issue, just spring rate.
Increase the oil level for more air springing effect towards the end of travel.
I'd be very careful going past 0.95 kg/mm regardless of what the charts and online calculators will for sure otherwise say, likely guiding you beyond 1.0 kg/mm.
(Doubly so keeping in mind that online calculators are notorious for calling for too stiff fronts and too soft rears when it comes to 919s.)
The 919 is more rear wheel weight biased and has horrendous fork stiction.
If your riding is not heavily performance oriented, and you are riding with a stock rear shock, I'd suggest 0.95s with as much as 20 mm of installed preload, 125 mm oil level height, and try that out first.
You want compliance in the front end, and you'll lose it with excessively stiff springs, and all of this gets worse if you ride on rougher roads.
Suggest you poll some of the guys here you are big boys and have done some spring rate changes at the front.

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post #7 of 7 Old 05-03-2013, 05:50 PM
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When I first got my 919 I was pretty close to your weight so I know how it feels to bottom the forks out. I would go with everyone suggestion about the fork springs first. Or if you want to go all out you can have your forks redone by Dan Kyle racing, made my bike so much better.

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