Suspension

5210 Views 15 Replies 11 Participants Last post by cbr250rakid, Aug 4, 2012

gette1

Discussion Starter · May 12, 2011

Any links out there for suspension? As soon as I sat on the bike (I have 13 miles on her), I noticed the suspension was soft.... the front brake too. The front brake is easy to correct. I've raced with a single disc... no worries there. No clue if heavier suspender springs are out there...

1 - 16 of 16 Posts

madd-trapper

· #2 · May 12, 2011

I thought the front brake was weak at first. After a few rides I either got used to it or it broke in(?). With downshifting and braking it stops on a dime.

CBR Downunder

· #3 · May 12, 2011

only the rear is adjustable, check your owners manual for details on how its done, the tool required is in your toolkit too

... As for the front, I'm sure that in time the aftermarket will produce different springs and probably valving options too, I'm not aware of any at the moment though

CBR Downunder

· #4 · May 12, 2011

madd-trapper said:
I thought the front brake was weak at first. After a few rides I either got used to it or it broke in(?). With downshifting and braking it stops on a dime.

that sounds about right to me, as all new brakes need "bedding in" whether its on a car or a bike

Luke

· #5 · May 12, 2011

The front is adjustable as well, just a little more work... These will most likely be available in the states shortly.

CBR250R MORIWAKI FRONT FORK PRE-LOAD ADJUSTER - Merchandise and Accessories Catalogue

DickyDck

· #6 · Jul 16, 2012 (Edited)

SATO RACING | Honda CBR250R ('11-) Fork Spring Preload Adjusters

http://sportisimotorsport.us/index.php?main_page=product_info&cPath=6_10&products_id=27

here are some, I'm considering these for my GFs 250

woolf

· #7 · Jul 16, 2012

www.racetech.com

tollarja

· #8 · Jul 16, 2012

You can replace the springs and internals on the fork. The shock is preload adjustable, but you can't change anything on it as it is a disposable unit.

roadster

· #9 · Jul 16, 2012

My cheap front suspension solution is to add oil to the front forks to limit the amount of air space and hence create the effect of a multi rate spring. This has to be done with some precision to avoid hydraulic locking and if a thicker grade of oil is used damping can also be increased.

I am using Ferodo ST pads on my ABS bike. They work well if kept warm but I wouldn't recommend them for city commuting or cold and damp weather.

regards Roadster

Jme250RA

· #10 · Jul 21, 2012

I just ordered springs and emulators from racetech! This is the first, and probably most important, mod I'll be making to my bike. While I was using the spring rate calculator I noticed the stock rate is 0.490 kg/mm. I'm 180 lbs and the spring rates for my weight were 0.80 kg/mm for street use and 0.85 kg/mm for track use. I went with the 0.80 kg/mm because if I want to lighten the bike ie. muffler and battery, then the suspension will get a little tighter. I can also adjust a bit more by playing with different oil weights. It should make a world of difference.

tollarja

· #11 · Jul 25, 2012

Jme250RA said:
I just ordered springs and emulators from racetech! This is the first, and probably most important, mod I'll be making to my bike. While I was using the spring rate calculator I noticed the stock rate is 0.490 kg/mm. I'm 180 lbs and the spring rates for my weight were 0.80 kg/mm for street use and 0.85 kg/mm for track use. I went with the 0.80 kg/mm because if I want to lighten the bike ie. muffler and battery, then the suspension will get a little tighter. I can also adjust a bit more by playing with different oil weights. It should make a world of difference.

Nice, let us know how it turns out! Hello confidence...

cbr250rakid

· #12 · Jul 25, 2012

Jme250RA said:
While I was using the spring rate calculator I noticed the stock rate is 0.490 kg/mm. I'm 180 lbs and the spring rates for my weight were 0.80 kg/mm for street use and 0.85 kg/mm for track use. I went with the 0.80 kg/mm because if I want to lighten the bike ie. muffler and battery, then the suspension will get a little tighter. I can also adjust a bit more by playing with different oil weights. It should make a world of difference.

r u sure about a .8 fork spring?
that's almost double the size spring from stock!

when i'd respring for my dirtbike, all i needed was a .02 - .06 jump over/under to from stock size.

Jme250RA

· #13 · Jul 25, 2012

I was a little surprised at the change in springs at first also but then I rode the bike and I think they are right. The bike is sprung way too loosely stock. I can't sit on the bike without losing an inch of travel and the suspension soaks up so much of the braking and accelleration energy. I guess I'll find out in a couple of days.

BBRMotosports

· #14 · Jul 25, 2012

cbr250rakid said:
r u sure about a .8 fork spring?
that's almost double the size spring from stock!
when i'd respring for my dirtbike, all i needed was a .02 - .06 jump over/under to from stock size.

That is correct, the bike is wsprung wayyyy to soft from the factory which is why the big jump to make it correct. Most 125/250F MX bikes are sprung and valved for a 150 160 LB rider so they are closer to the average guys weight which is why you didn't need such a big jump in spring weight.

Jme250RA

· #15 · Aug 3, 2012

I got thinking about the stock spring rate and wondered what rate 0.49 kg/mm is for but the calculator on the Racetech site only goes down to 31 lbs for rider weight. Even then the spring rate is 0.596 kg/mm. The weakest spring they sell is a 0.70 kg/mm and that is for a rider that weighs in at around 110 lbs! I'm guessing that the stock springs were put in just to keep the bike from falling over while on the kickstand.

cbr250rakid

· #16 · Aug 4, 2012 (Edited)

Jme250RA said:
I got thinking about the stock spring rate and wondered what rate 0.49 kg/mm is for .... I'm guessing that the stock springs were put in just to keep the bike from falling over while on the kickstand.

you can come close to finding this out by measuring the sag.
---------------------------------------------------------------------------
Rider Sag = Measured sag of bike and rider w/ rider and rider's gear.
Free Sag = Measured sag of just the bike, no rider, no rider gear.

Front -
Rider Sag - 30-35mm (25-30% of Full Travel)
Free Sag - 15-20mm (60-70% of Rider Sag)
Rear -
Rider Sag - 20-30mm (race), 30-35mm (street) (25-30% of Full Travel)
Free Sag - 5-10mm (extremely light bikes use less) (15-25% of Rider Sag)
----------------------------------------------------------------------------
me = 162 lbs.
w/ stock front springs:
my rider sag = 45mm
my free sag = 27mm

so, since i'm 10mm over the rider sag, then for each mm over, that will equal a certain amount of weight over the spring's ideal rate. (fyi, springs are often rated in kg/mm). if it's true that the stock spring rate is .49kg/mm, then for each mm over, that's .49kg extra weight, or about 1 lb over.
to drop from 45mm to the 30-35mm rider sag range, that's a 10-15mm difference.
so i'd have to be roughly 5 to 7.5kg lighter (11 to 16.5lbs). then from my math, the stock fork springs will work best for someone who weighs between 145-151 lbs.

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