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yz125 Spring Rates for a bigger guy

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Well hell.......I'm back on a "maybe I need a yz125" kick.

Just wondering what the stock rates are for:

02-04 era

06+ era

then, what are rates for 195-200lbs (no gear)

Would love to hear what people sprung UP to.

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Im 220 before gear, Im running .48kg fork springs up front and a 5.2kg spring in the rear.

Stock rates on my bike are .41 in the forks and 4.6 in the rear. Way undersprung for us bigger guys. The 06 is .42 forks and 4.7 shock.

Check out racetech... use the spring calculator to figure you appx spring rates.

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Im 220 before gear, Im running .48kg fork springs up front and a 5.2kg spring in the rear.

QUOTE]

That sounds about right, That would be very similar to 450 spring rates from the same year.

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correct... Id like to go up one step in the front but I cant find anyone that has heavier fork springs than that.:smashpc:

I think racetech is good enough to give you a ball park figure, unless you really know the ins and outs of suspension and know exactly what you need. Fact of the matter is you cant beat talking to a professional suspension tuner and giving him the in depth details about your riding and he will adjust accordingly including spring rates and valving. Best part is, with most of them your not out any money if it doesnt work for you. Theyll fix it for free! Cant beat that IMO and is the best spent money on any bike.

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One thing to remember with race tech is that they recommend springs for thier Piston and Valving.

Alot of people say valving should not matter when choosing spring rates and they may be right? But if that were true then why did my old 1996 kx250 come stock with .38 springs in the forks but still work well? Valving!

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all the spring rate calculators are out of whack .all list too stiff fork springs and too soft a shock spring.moto pro,s is the closest and mx tech is the worst.

race tech has me at .562 fork and 5.68 rear.i tried those numbers.fork has no sag ,bike won,t turn.rear ride height can,t even be achieved with such a light spring.

i ended with a .48 fork and a 6.7 rear spring.springs have to be chosen by sag numbers.

try motopro,s generator and stay to the low side on the fork and to the heavy side on the shock.

i would try a .44 front and a 5.4 rear.

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all the spring rate calculators are out of whack .all list too stiff fork springs and too soft a shock spring.moto pro,s is the closest and mx tech is the worst.

race tech has me at .562 fork and 5.68 rear.i tried those numbers.fork has no sag ,bike won,t turn.rear ride height can,t even be achieved with such a light spring.

i ended with a .48 fork and a 6.7 rear spring.springs have to be chosen by sag numbers.

try motopro,s generator and stay to the low side on the fork and to the heavy side on the shock.

i would try a .44 front and a 5.4 rear.

Interesting. A while back I ordered some springs from RaceTech, and "kinda" thought the same thing. I mean "kinda" cuz I was not off as bad as you are listing, mine was just slightly off. But yeh, I was thinking to ROUND UP for the rear, and ROUND DOWN for the forks (i was in the middle, a spring they didn't make for front&rear). Already was thinking that before you posted. I'll try another calculator and see what it says as well. Thanks for the input.

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I'm 193 without gear on a yz144. I have .44 in the forks and 4.8 in the rear. I have been testing the bike and by softening the comp out back it allows me to get on the gas way sooner without the bike fighting me. Now I just need to get the front under control. Seems like when accelerating on rough sections of the track the front seems busy and rough. I'm sure with more time testing and probably take some more comp out of the too.

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all the spring rate calculators are out of whack .all list too stiff fork springs and too soft a shock spring.

What he said. I got into bikes after years knowing my way around car suspension really well. I'm a big guy, so I assumed I'd have to respring and bought the rates indicated by Race Tech's calculator. Not stiff enough in the rear, too stiff in the front.

Find a setup guide that tells you what your free sag and race sag should be. Dwight has guidelines in his sticky in the off-road section. That's my interest, so I haven't looked for guidelines for MX, but could easily understand them being a little different. Once I got my head around them, Dwight's numbers made total sense to me as a suspension guy.

Get your bike as close as you can with the springs that are on it, then calculate the rates you need to get the sag number targets right. There is a little error built in because of the non-linearity of the linkage if you're way off on rate to start with, but it's probably not bigger than the steps between available spring rates.

It's just fractions and ratios, the math is simple. If you don't have Excel installed, you should be able to set up a Google Docs spreadsheet to automate it for different measurements and setups.

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