94-98 KX 250/KDX220

OsoBlanco · Post by **OsoBlanco** » 01:16 am Mar 19 2013

I just started a hybrid project. The motor is from a 2001 KDX 220R and it's going in a '98 KX 250. I looked around for quite awhile for a reasonably priced '99-newer KX 125 but found nothing. I did get a great deal on a '98 KX 250 roller.

The first issue I've come across is the difference in swing arms. The 99-newer look like they are quite easy to trim at the pivot points but the '98 is far more involved, appears to require a bunch of welding. I've looked around for a 94-98 swap thread but haven't found anything. Narrowing the motor case a better option?

Can anyone point me in the right direction?

Cory

Tedh98 · Post by **Tedh98** » 06:48 am Mar 19 2013

Do you have a picture of your swing arm?

royadams · Post by **royadams** » 08:00 am Mar 19 2013

When I did my kdx250/rm250 conversion I had to cut the cases. The swing arm did not have any extra room to remove. It was a pain to remove some from the cases.

CoronasAndChips · Post by **CoronasAndChips** » 08:25 am Mar 19 2013

Just curious, why are you putting new motor in older frame? I put 97' KX 250 forks and rear shock on my 2002 KDX 200. The rear shock bolted right in and RB did the stem swap.

OsoBlanco · Post by **OsoBlanco** » 12:13 pm Mar 19 2013

CoronasAndChips wrote:Just curious, why are you putting new motor in older frame? I put 97' KX 250 forks and rear shock on my 2002 KDX 200. The rear shock bolted right in and RB did the stem swap.

I thought about just doing the suspension on the KDX and being done with it. I've ridden a few upgraded KDXs and a couple hybrids. The suspension upgraded KDXs are a huge improvement over stock but I preferred the handling on the hybrid. Maybe both hybrids were totally dialed in and both KDXs weren't, maybe it's geometry, maybe it's just mental... I don't know. If I had come across a '99 newer roller I would have jumped on it. I have no doubt that the '98 KX frame and suspension will be a huge improvement of the KDX and that's all I'm looking for.

Below is the '94-'98 swingarm. On the '99-'02(?) unit, the left and right pivot locations look like the right side of this one. There is a lot of meat that can be trimmed without getting into the hollow casting. I can cut this one back the same on both sides and TIG a plate in to fill the hole on the left side. I'd rather not have a custom swing arm so if I damage it in the future, it can easily be replaced. I'm leery about cutting on the engine cases as I don't know how much thickness there is to work with.

Tedh98 · Post by **Tedh98** » 02:55 pm Mar 19 2013

Thanks for the picture, makes sense now.

Reminds me of a YZ125 I had that I was considering turning into a hybrid. But with that swingarm, both sides would need to be cut and then closed back up.

My $.02 is that I'd rather modify the swingarm than narrow the cases. How often do swingarms break or get damaged so badly you can't use them? Plus you can keep your eyes open for a cheap spare on eBay in case you need it.

If you or a machine shop screws up narrowing the cases, you've got a bigger problem on your hands.

Post by **bufftester** » 03:04 pm Mar 19 2013

The 99-02 swingarm will bolt right up to the 98 frame. The only difference made from 98 to 99 was that they removed a bunch of material in the front of the swingarm to reduce weight (which is why the 99-02 ones have a thinner left hand section thatn the 98). Linkage rates were the same. Best bet would be to sell your 98 swingarm and get a 125/250 99-02 one. That's probably the easiest of the changes to the frame. More difficult (if you suck at welding like I do) will be the motor mounts and exhaust fitment. The 250 frame is a bit larger in the cradle area than a 125 or 220, so you may have to weld an extension to the head of your pipe to clear the cradle. On the hybrid I just finished (a 2001 125 frame with a 2001 220 motor) the stock pipe just cleared the downtubes by 1/4 of an inch after I ground down the pipe seam weld and added a torque ring (which is basically a 1/4" spacer). Looking forward to seeing more of the build, not many 220 powered 250's, although the KDX250 I hear is almost a straight bolt-on to a KX250 frame.

Tedh98 · Post by **Tedh98** » 08:54 am Mar 21 2013

seems like a good deal: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... SS:US:1123

OsoBlanco · Post by **OsoBlanco** » 01:40 am Mar 22 2013

Tedh98 wrote:seems like a good deal: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... SS:US:1123

There are a few cheap ones floating around, some with linkage and brakes for under $100. I'm just going to cut up the stocker and TIG a filler plate in. I thought about picking up a new swing arm but would rather have a matching bits on the bike. I'll deal with the stock unit.

I'm a bit annoyed at the moment. Bought the bike as a '98, is actually a '95. Swing arms are different. 94-95, 96-97, 98, 99-06 is the break down for pivot rebuild kits. The '98 kit I bought definitely doesn't fit the '95. The '98 clearly has bigger bores for the bearings. I should have checked the VIN before I bought the bike

Anyone need a '98 KX 125/250 pivot rebuild kit?!

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