Fat Guy Suspension

jockjamz
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jockjamz
Hey all,

Looking for some advice on a suspension setup for a larger rider on a budget.

2014 Yamaha YZ450F
Stock Front Spring Rate: .49 kg/mm
Stock Rear Spring Rate: 5.9 kg/mm

RaceTech recommends for my weight (250lbs) and riding style to switch to a .50 kg/mm front spring and a 6.92 kg/mm rear spring.

My question is changing the front spring that little worth the money? Is it absolutely necessary to change the valves in the shocks or can you get away with just going to a heavier rear spring in my case, specifically the rear?

Any suggestions on what I should do. I typically just trail ride in the mountains and recreationally maybe ditch bang.

Thanks for welcoming me to the forum!

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kb228
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kb228 12/15/2020 12:46pm
12/15/2020 12:46pm
Honestly i dont think that front spring rate is correct. Stock’s target weight is less than 200lbs. I had to get the heaviest racetech sells. Id imagine youd be up there too.
m21racing
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m21racing 12/15/2020 2:29pm
12/15/2020 2:29pm Edited Date/Time 12/15/2020 2:30pm
At 250lb you are around 3 rates up from stock. Now, the yami changed in '15 or '16 to a 5.7 on rear of 450s. I would use that as a base rate to go from. Three rates up would be 6.3. Or 6.4, Especially in a woods setup.

Yes, I would definitely valve the suspension for spring and terrain in your situation.
mwssquad827
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mwssquad827 12/15/2020 7:05pm
12/15/2020 7:05pm
Ya I’m .52 and I’m 200
motomike894
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motomike894 12/15/2020 7:26pm
12/15/2020 7:26pm
I’d say more like .54 fork springs, but also depends on your riding speed etc, but going that heavy on springs without revalving it might result in some funky acting suspesnion.

I run a .54 forks and 6.8 shock that’s heaviest I can get without special Ordering, technically I need another size heavier but my stuffs also valved so it ends up working pretty damn good for me

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Falcon
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Falcon 12/16/2020 1:24pm
12/16/2020 1:24pm
To answer your question about the valving, I'd say the stock SSS setup is pretty damn good. I would definitely try getting it spring correctly for your weight and then ride it and see. You should be able to get right where you want via the clickers.
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jockjamz
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jockjamz 12/16/2020 1:57pm
12/16/2020 1:57pm
This is awesome. Thank you for all the info guys!
Rider 5280
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Rider 5280 12/16/2020 8:04pm
12/16/2020 8:04pm Edited Date/Time 12/17/2020 9:02pm
I adapted one of my buddy bikes I built up for a friend who is 6'5" and 300 pounds (bike is a 2007 Honda CRF450R). The final setup that works for him outstandingly for mountain trails and mx tracks is (focusing only on larger rider mods):
-Correct springs in OEM forks/shock, no valving changes were needed. Used Race Tech's spring calculator.
-ROX 3" Risers
-Core Moto longer front brake line for ROX Risers
-FasstCo Flexxbars with red compression and rebound dampers
-SDG tall seat
-FastWay EVO 3 pegs that you can lower (1/2 inch, I think)
-Hammerhead billet shift lever with +20mm tip
-ARC Memlon levers for full adjustability and crash survival

Hope that was usfeful.
Rider 5280
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Rider 5280 12/16/2020 8:09pm
12/16/2020 8:09pm Edited Date/Time 12/17/2020 6:39pm
Falcon wrote:
To answer your question about the valving, I'd say the stock SSS setup is pretty damn good. I would definitely try getting it spring correctly for...
To answer your question about the valving, I'd say the stock SSS setup is pretty damn good. I would definitely try getting it spring correctly for your weight and then ride it and see. You should be able to get right where you want via the clickers.
I agree based on limited experience.
lumpy790
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lumpy790 12/17/2020 7:33am
12/17/2020 7:33am
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and now with std rebound valving it’s a pogo stick. Same thing with compression
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Falcon
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Falcon 12/17/2020 8:24am
12/17/2020 8:24am
lumpy790 wrote:
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and...
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and now with std rebound valving it’s a pogo stick. Same thing with compression
Good point. I hadn't thought about the rebound side of the equation.
soggy
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soggy 12/17/2020 8:59am
12/17/2020 8:59am
Since you are riding trail and the yz comes setup for moto I don’t think you need to jump up in spring rate so much. If you were riding moto yes, but on trail you want a softer spring IMO
yz133rider
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yz133rider 12/17/2020 9:41am
12/17/2020 9:41am
lumpy790 wrote:
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and...
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and now with std rebound valving it’s a pogo stick. Same thing with compression
But while we’re on this topic, doesn’t the riders weight correlate to the spring and thus the forces and speeds actually equal out making it so the valving isn’t effected. Stiffer spring because of heavier rider means the spring isn’t rebounding faster because the riders weight offsets that.

I’m sure I’m wrong and am open to hear why.
jockjamz
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jockjamz 12/17/2020 12:58pm
12/17/2020 12:58pm
lumpy790 wrote:
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and...
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and now with std rebound valving it’s a pogo stick. Same thing with compression
yz133rider wrote:
But while we’re on this topic, doesn’t the riders weight correlate to the spring and thus the forces and speeds actually equal out making it so...
But while we’re on this topic, doesn’t the riders weight correlate to the spring and thus the forces and speeds actually equal out making it so the valving isn’t effected. Stiffer spring because of heavier rider means the spring isn’t rebounding faster because the riders weight offsets that.

I’m sure I’m wrong and am open to hear why.
This makes sense to me in theory. Good point!
captmoto
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captmoto 12/17/2020 4:57pm
12/17/2020 4:57pm
yz133rider wrote:
But while we’re on this topic, doesn’t the riders weight correlate to the spring and thus the forces and speeds actually equal out making it so...
But while we’re on this topic, doesn’t the riders weight correlate to the spring and thus the forces and speeds actually equal out making it so the valving isn’t effected. Stiffer spring because of heavier rider means the spring isn’t rebounding faster because the riders weight offsets that.

I’m sure I’m wrong and am open to hear why.
I couldn't adjust the pogo out completely on my FC450 with heavier springs. You want the clickers to be as near the middle of the range as possible. After 3 spring rates you need a re-valve to get the most out of the springs.
mxracer666
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mxracer666 12/17/2020 5:26pm
12/17/2020 5:26pm
lumpy790 wrote:
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and...
Valving and springs go hand and hand with each other. Think of it this way. Heavier spring rebounds back with more stored force pushing back and now with std rebound valving it’s a pogo stick. Same thing with compression
yz133rider wrote:
But while we’re on this topic, doesn’t the riders weight correlate to the spring and thus the forces and speeds actually equal out making it so...
But while we’re on this topic, doesn’t the riders weight correlate to the spring and thus the forces and speeds actually equal out making it so the valving isn’t effected. Stiffer spring because of heavier rider means the spring isn’t rebounding faster because the riders weight offsets that.

I’m sure I’m wrong and am open to hear why.
That would make some sense...if your wheels were always on the ground. But you are going to be jumping some stuff right? You don't want your suspension rebounding WAY too fast on takeoff, right? Personally, I think you could adjust for this with-in the range of of the stock rebound adjusters, but in a perfect world you would want your adjusters in the middle of the range.

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