cr 125 rear spring

[BDAY]

i just bought a cr 125 and the rear end bounces up on the bumps and just shakes the crap out of me.
i bought it used from a local dealer so i don't know what the last rider weighed and i think he may have put a heavy spring on it.
how do i tell if its a heavy spring and what would you recommend for me. i weigh 145 w/o gear and how much would it run to have someone change it $$$. all help would be appreciated as this is starting to bother me.

 

[bikepilot]

Start by setting the sag. You should have about 25mm of sag without you one the bike and about 95-105mm of sag with you on the bike, geared up as though you were going riding. If the spring is way too stiff you will end up with too much unladen sag and not enough laden sag. Too soft and it will be the other way around.

Once you get the sag sorted set the clickers all back to the stock posistions and work from there.

Springs are $75-125 depending on brand. Don't know how much a shop would charge to install it. I would recomend that you buy a factory honda service manual and do your own work.

good luck

 

[Anssi]

You have to check your sag. Get the bike up on a stand and measure the distance from the rear axle to the fender (about straight up, doesn't really matter as long as all measurements are from the same spots).

Then put the bike on the ground and measure the same distance. The difference between these measurements should be about 20-35 mm. (about an inch).

Now sit on the bike or get some support and stand on the pegs and have someone do the same measurement. This should come out to about 90-110 mm difference from the bike-on-stand measurement.

If both of the differences are off to the same direction (too much or too little) you can adjust preload to get them into range. For a spring that is too heavy, if the first difference (stand to bike on ground) was ok, the second (stand to you on bike) would be too small (less than 90mm).

 

[BDAY]

when the bike is sitting there i can lift up on the rear it will come up about 25-30 mm but when i let go it stays up there until i push it back down. when i sit on it, it has around 50-75 mm i didnt bother to mesure because i could tell it wasnt enough

 

[Anssi]

The rear should not just stay there when you pull it up. It might not go down the full 25-30 mm quickly, but should definitely drop. You should probably check your linkage as well to make sure it moves freely (easiest to do when you remove the shock which you will have to do anyway to replace that spring which is definitely too heavy for you).

The spring is not hard to replace yourself.

 

[BDAY]

how do i find out what spring i have and what to get

 

[Anssi]

The suspension companies, such as racetech have spring rate calculators on their web sites you can use for free.