Installing an 08 shock on a Classic
The 2008-12 shock is a direct swap onto the older EX250F. This has become the first choice for riders who want a firmer shock but don't want to pay the price for an aftermarket one. The J model shock is stiffer. Sag is much less than with an OEM F shock. It's much better when riding 2-up, and the bike will squat less at the rear when accelerating. It should make the handling better (YMMV). Since it's designed for basically the same bike, there's not much chance it will be too stiff for most people. It will only cost you about 20 minutes of your time and the price of a used shock to find out.
The 08-12 shocks are all the same, part number 45014-0234-23J. Here they are, an '08 EX250J shock on top and an '06 EX250F shock on bottom:
In this picture, the newer one is on the bottom. This one didn't have the Kawasaki sticker on it, but it did say it was made by KYB (Kayaba), which is the OEM supplier.
Mounting specs are almost identical. The top fitting is 0.5mm less wide on the EX250J. That could easily be due to one of the fittings being out of spec, or having been slightly bent. The other spec difference is that the EX250F shock is 2.0mm less tall (from center/center of mounting holes). It's likely that the '06 EX250F shock settled while in use and that they were closer to identical when new.
This photo shows the mounting points, with the EX250F shock on left and EX250J shock on right. The difference in the top fittings didn't affect the installation at all.
Installation takes about 20 minutes and is very easy. The only extra adjustability on the new shock is preload. It still doesn't have compression or rebound damping. Our suspension man says that the difference in spring height doesn't have any meaning one way or another.
One thing to keep in mind is that with Sport Demon or other 90-series tires on the bike, you'll probably have to put a piece of plywood under the centerstand when you need to get the rear tire off the ground.
Here are photos of the EX250J shock installed.
Initial impressions from one person who sold his bike shortly after he did it:
And initial impressions from a new rider who made the switch:
Our recommendation for preload adjustment is to start with the softest setting, and be careful until you're used to the new shock. If it feels like you could use more preload, adjust it one notch at a time until you get to where you're comfortable.