New Rear Shock Spring - KDX220

I weigh 220lbs without gear.

What rate and brand shock spring should I be replacing my OEM shock spring on my KDX220?

What other internal changes could also be made within the shock itself to better suit handling and also to complement my kx250f front end?


I weigh 210lbs, and went with Race Tech's recommendation of a 5.2kg/mm. Stock is 5.0kg/mm, and you wouldn't think .2kg/mm could make such a difference, but it does. To get 3.25" of race sag, the adjuster collar is a full 1/2" higher on the threads than it was at 3.50" with the stock spring. Haven't checked the free sag yet, but since I'm running it 1/4" or so higher in the stroke than normally recommended, I figure it will be a little short.

Shock internals are just good condition stock. You could Gold Valve it I guess, but I'm finding with a little adjustment of the clickers, the stock valving is working very well.

The ride if I'm setting is almost MX harsh on both ends, but standing, it's smooth as silk, and tracks perfectly straight through all normal hack. Big hits aren't big anymore, and it jumps/lands (within reason, it's still not an '11 KX250F) like a dream. I'm lovin' it.

Go to Race Tech's site ( and see what they say for you.:thumbsup:

Edit: I see the MX Tech site David_L6 posted recommends the same fork & shock springs for me as Race Tech does (same price too). Looks like the common theory, go with whichever company you like the looks of best.:blah:

You may want to look at a 5.2, 5.3 or 5.4 rate spring. Try a new (correct for your weight) shock spring before doing anything to the shock internally. Since you have been riding on a too soft spring this whole time, every idea you have about improvement is based on poor information from using the wrong spring.

Shoot for 100mm of sag on a KDX, then check the bike's static sag.

Mnay thanks.

I di dthe online test at mx-tech and it comes out at 5.4 rate spring.

THis bike is going to be great when finished :-)


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By Tedstrom
      Alright so I just rebuilt my 2012 kx250f complete rebuild. I put the motor back in the bike get everything hooked up and ready to go it takes a few kicks at first (obviously) but after it starts it sat and idled just fine for a while then it stalled out. Tried to start it again wouldn't start I took the spark plug out of it it looked good I was dark and wet. I cleaned it then put the spark plug back in it it took a few kicks but started right back up again then after a while it stalled out again and now I can't get it to start again!? Any help would be greatly appreciated thank you guys and girls for reading and hopefully for the help!!!
    • By luke8500
      Hi all,
      I have a 2004 Kawasaki kx250 that died suddenly on me the other day. all i can get it to do is backfire every once in awhile. Tested the resistance and everything of the magneto and stator with a multi-meter and all is good.  Coil is new oem Kawasaki the reeds are brand new vforce and the top end and carb have been completely rebuilt.  key on crank is intact and all the timing marks are lined up. I hooked a timing light to it and spun the motor over really fast and found that it is sparking way to late.  The service manual says that it is supposed to fire 14 degrees before TDC but it is sparking way after TDC.  Im thinking its a fried CDI box since its the only thing i wasnt able to check.  Any help would be appreciated
    • By luke8500
      Hi all,
      I have a 2004 kx 250 2 stroke and it wont start.  it only backfires.  I was out riding it one day and came up to a stop so the bike was just idling and it started to try and die so i revved it up a few times then let it die and now it wont start back up.  It only pops or backfires when you kick it.  Its getting good spark and i just put a brand new plug and coil in it. I took the reeds apart and they look like they're brand new.  It was running great before so i dont know what happened.  Im thinking it could be a fuel problem even tho the plug is a little wet if you take it out after a bunch of kicking.  Any help would be greatly appreciated 
    • By Zach121
      Alright, found three bikes all located where i live in Texas. I know they're all very different, but if you could tell me what you think each bike is worth, and which one would be the best deal. Thanks.
      Notes: Both 2 strokes have new top ends. I think the front brake lever is broken on the kawasaki.
      KX250 2002 $800-$1000?

      YZ125 2000 $1250

      KTM 400SX 2002 $1200

    • By Ryan Turner
      So I'm at a bit of a cross roads, I currently own a 06 rm250 and I love it. I also have a 02 kx250 which I'm selling with intent to buy a newer two stroke. I can't afford a newer ktm and the older ones aren't that great and kawasaki never impressed me. so I'm stuck between 06 yz250 and 05 cr250. I've heard the yz and rm after 06 are almost the same bike just the Suzuki handles better and the Yamaha has better suspension. So I'm not sure if I wanna buy carbon copy of my bike with slight differences. That's why I'm interested in a cr250 I heard the 02+ models RC valves are shit garbage but was mostly fixed in the 05-07 models. I ride at a track and at some bogs down the road from me. So from people who have owned both, what would you recommend. I know the cr is known for a hard hitting power band which I enjoy since im an aggressive rider. Should i just see which deal comes my way first.