ZX6R rear shock *sorta* howto : KawiForums.com Kawasaki Forums: Kawasaki motorcycle forums

TheDuck · 01-16-2010, 07:33 PM

This weekend I have a cold, its raining and I don't have to work for a change, so I had to do something to keep myself busy! As a big plus, its actually WARM enough (surprising since this is supposed to be Florida!) to work on this thing, oh, and I was told that this couldn't be done... so here it is:

Tired of the rear shock being too bouncy for all of the 6'3" 250lbs of meat that I am, (much heavier with gear and other travel-related equipment) plus and not having adjustable bump or rebound left me a little frustrated.

I had the preload adjusted to the max and the thing still sagged a little too much. So I've known I wanted to do something to upgrade the rear, and the SV650 shock that some people have recommended really didn't leave me happy. I have an SV650 and its shock isn't adjustable for anything other than preload either.

I know that the 250 isn't meant to be a performance bike, but with a little work, who says it can't be?

I put the triple stand on the front and supported the underside of the bike with a floor jack and some wood under the kickstand to ensure that the bike's weight was NOT on the back wheel. Then popped off the caps on the side of the frame and removed the top shock bolt, then removed the bottom and pulled the shock downwards and out. Then I dug in the parts bins for a suitable replacement.

From left to right: 08-10 250R, 04-05 10R, 06-07 ZX6R

The 10R shock and the ZX6 shock measure the same length, but they are both about 1" longer than the 250R shock. This will raise the rear some 2 inches or so. We'll see how that turns out, and if I don't like it I'll get a set of lowering links.

The other dimensions such as the inside width of the forked bottom and the eyehole width at the top are identical on all, but the 250R shock has bigger bolt holes on top and bottom. This should be easy to ream out to the right size.

ZX6R on left, 250R on right:

The 10R shock also quite obviously has a different reservior from the ZX6R and the 250R doesn't have one at all! There will be some work to make this fit in on my 250.

After poking around I decided the 10R shock will fit better on another one of my projects so I decided to keep that one for later.

The ZX6R shock is much larger in every way, the spring is bigger, its about 1" longer and required the bike to be disassembled to make sure I can get it situated into its new home.

TheDuck · 01-16-2010, 07:34 PM

I would also like to add that anyone that is interested in this mod may not be able to do it with a stock airbox (though I think you can heatgun it and try to warp the bottom.) Or you can spend some money and get an Ohlins with a remote reservoir, or some other 2nd gen 250 aftermarket shock (I don't know of any at this time.)

Begin teardown, for anyone that has deleted the airbox knows just how much work it is to get into the middle of this bike. You have to tear off the complete undertail, so that requires removing anything attached to it, and anything attached to the things attached to the things attached to the things attached to the things attached to the things attached to the things attached to the things attached to the things attached to the things attached to the things attached to the things attached to the undertail.

Needless to say you wind up with a big pile of stuff. Pile your parts someplace safe where they won't get stepped on or disturbed:

And here's the bike sans rear end:

And a closeup of the top shock mount on the frame (note the pod filters):

I went to drop the ZX6R shock into place, but it wouldn't fit between the suspension links underneath, they weren't spread wide enough apart, so I took them off then mounted the shock, then attempted to measure how much clearance I needed.

I found that the links are offset a bit to the right, so the left side needed more washers to clear the new shock. This also required some longer bolts, so a trip to the hardware store was required, upon return and assembly, we got this:

TheDuck · 01-16-2010, 07:34 PM

So now comes the top shock mount... the top hole had been reamed out to fit the 250R shock bolt, but it just would not line up with the hole. It was really close but the shape of the shock interferred slightly with the frame. I shoved a screwdriver in there just to hold it in place, thats as close as it got. You can also see that the undertail was trimmed a little bit for clearancing of the reservoir.

There was two options, grind the frame to fit, or grind the shock, or a little of both. I believe when you're trying to add something custom that doesn't belong there, and then you have a problem so you need to revert back to stock, its better to modify your add-on rather than the bring the moutain to Mohammed.

I fired up the angle grinder and zinged off a little metal from the top of the shock... I didn't need to take off much, and its aluminum so it only took a few careful minutes to cut it right.

TheDuck · 01-16-2010, 07:36 PM

So the shock is now officially mounted:

TheDuck · 01-16-2010, 07:37 PM

I put the wheel on and pushed down on the tail and was quite surprised how much stiffer it was than the other 250 in my garage. This one actually pushes back when you push down on it, it doesn't just give out like an 80 year old without his viagra.

I threw the seat on and bounced my ass on it (keep the jokes to yourself) a little to be sure that nothing was binding or loose. My very first impression on it again was that it felt so much tigher than before, and yes indeed it was about 2" taller with a much more aggressive stance. This will affect my rake and trail on the front end.

I continued trimming the undertail until I had a shape that I was happy with an 1/8" gap around the reservior that cleared the shock in its full motion. After cutting it I thought to myself that I should have just heated it up with a heat gun and pressed the shock into it to make a nice and NEAT impression in the undertail... ahh well, next time. I'm going to put a plastic flap with holes that line up with the battery box bottom holes to cover that area and keep road grime off my air filters.

TheDuck · 01-16-2010, 07:38 PM

And lastly here it is on the bike (ignore the worn tire, its out of life so I have been smokin' it getting my money's worth of fun times out of it! It goes in Tuesday for a new one!):

Without making any adjustments to the shock, I took it for a ride around the block, and the first thing I noticed was that when I got on the throttle the rear end doesn't sag like it used to. Its firm, I can feel the rear end keeping its place, also when getting on the brakes the front doesn't dive as much, probably because the rear shock doesn't rebound as quickly as the stock shock thus pushing the tail up.

It also turned a lot easier with the tail higher, a lot easier than what I remembered before. I wanted to push it harder but I didn't press my luck on the wet roads though.

Here is a photo of the blue modified bike next to the red stock bike. Please excuse the photo darkness the rain wasn't helping, and the flash wasn't cutting it.

The rear is just under 2" taller when standing upright. The kickstand seems a little short, but works ok. I will ride it like this for a little bit and possibly invest in links later unless I can find some in the garage someplace.